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15 Biological Chemistry Part (ii) Nucleic Acids (b) Oligonucleotides and Polynucleotides By M. J. GAIT Medical Research Council Laboratory of Molecular Biology Hills Road Cambridge CB2 2QH 1 Introduction In 1980 an important change of emphasis took place in the field of nucleic acids. On both sides of the Atlantic there was a considerable easing of the containment regulations under which DNA could be cloned and this led to a rush to isolate genes directly from chromosomal DNA and to set up systems for the expression of DNA in bacteria and other micro-organisms. Whereas between 1977 and 1979 much effort had gone into the total synthesis of genes now it became possible to derive these sequences from relatively impure preparations of mRNA via cloning of its complementary DNA (cDNA).First signs of the change in emphasis appeared in late 1979 with a report on the expression in bacteria of a gene for human growth hormone.’ Only the terminal 84 base-pairs corresponding to the first 24 amino-acids were synthetically derived. The remaining 551 base-pairs (167 amino-acids) were obtained from a restriction fragment isolated from cloned cDNA. Then early in 1980 amid a storm of publicity the sequences of the cDNAs corresponding to human leukocyte interferon (inter- feron a)*and human fibroblast interferon (interferon p)”‘“were announced. Within a few months interferon cDNAs had been expressed in ba~teria.”~ By the end of the year much information had already been accumulated on the structure of interferon genes,7 which appeared to be arranged in multiple sets.The frenetic pace of development of the subject was undoubtedly due to the high level of D. V. Goeddel H. L. Heyneker T. Hozumi R. Arentzen K. Itakura D. G. Yansura M. J. ROSS G. Miozzari R. Crea and P. H. Seeburg Nature (London) 1979,281 544. ’N. Mantei M. Schwarzstein M. Streuli S. Panem S. Nagata and C. Weissmann Gene 1980,10 1. T. Taniguchi S. Ohno Y. Fujii-Kurijama and M. Murumatsu Gene 1980 10 11; R. Derynck J. Content E. DeClercq G. Volckaert J. Tavernier R. Devos and W. Fiers Nature (London) 1980 285 542. M. Houghton M. A. W. Eaton A. G. Stewart J. C. Smith S. M. Doel G. H. Catlin H. M. Lewis T. P. Patel J. S. Emtage N. H. Carey and A. G. Porter Nucleic Acids Res. 1980,8,2885. R. Derynck E.Remaut E. Saman P. Stanssens E. DeClercq J. Content and W. Fiers Nature (London),1980,287,193. D. V. Goeddel E. Yelverton A. Ullrich H. L. Heyneker G. Miozzari W. Holmes P. H. Seeburg T. Dull L. May N. Stebbing R. Crea S. Maeda R.McCandliss A. Shoma J. M. Tabor M. Gross, P.C. Familletti and S. Pestka Nature (London) 1980 287,411. ’ S. Nagata N. Mantei and C. Weissmann Nature (London) 1980 287 401; G. Allen and K. H. Fantes ibid. p. 408. 310 Biological Chemistry -Part (ii)b Oligo- and Poly-nucleotides 311 industrial interest in the possible exploitation of interferon as antiviral and anti- tumour agents but at the end of 1980 the clinical value of interferon still remained in doubt.8 Another major highlight of 1980 was the award of the Nobel prize in Chemistry to Walter Gilbert from Harvard and Frederick Sanger from Cambridge for their studies in sequence determination of DNA together with Paul Berg of Stanford for his original work on recombinant DNA.This award clearly marks the world-wide impact that their discoveries have had on the advancement of science. 2 Determination of Base Sequences of Nucleic Acids Extremely detailed protocols have been published recently for both the Maxam- Gilbert' and the Sanger 'dideoxy' lo methods of DNA sequencing the basic prin- ciples of which were outlined in last year's Report. Some refinements have been made to the chemical reactions involved in the Maxam-Gilbert approach.' A virtually Gua-specific reaction is now obtained by N-7-methylation with dimethyl sulphate followed by base displacement and strand scission using piperidine.Removal of Gua + Ade is achieved by depurination with formic acid. The DNA is then broken at these sites with piperidine. Conditions for pyrimidine-specific modification are unaltered. Both Cyt and Thy are modified by using hydrazine but only Cyt residues react when the hydrazinolysis is carried out in the presence of 1M sodium chloride Again base displacement and strand scission occur on treatment of the DNA with piperidine. An Ade > Cyt specific cleavage is also recommended. Here the bases are ring-opened by treatment with sodium hydroxide. Once more reaction of the DNA with piperidine completes the cleavage. The only major change in the Sanger approach lies not with the method of sequence determination" but with the increasing use of bacteriophage M13 as a vector for cloning of DNA fragments." These are usually generated by the use of yestriction enzymes to cut the DNA of interest the pieces being inserted by ligation into the double-stranded replicative form of phage M13 which has been pre-cut with the same restriction enzyme.After transformation of Escherichia coli cell clones are selected at random and the M13 DNA is isolated. This is single-stranded and the sequence of the inserted DNA is determined." DNA polymerase mediates the synthesis of radioactive complementary strands of DNA that each terminate in a 2',3'-dideoxynucleoside.Synthesis is directed by the use of a specific primer at a site on M13 immediately prior to the insert.The primer can be derived from a restriction fragment or can be a synthetic oligodeoxyribonucleotide (see Section 3). The method has been used to obtain the sequences of both human and beef mitochondria1 DNA,".'* each being ca. 15 000 base-pairs long. Whereas the Maxam-Gilbert method is perhaps most often chosen for DNA of a few hundred 'J. L. Maux Science 1980 210,998. A. M. Maxam and W. Gilbert in 'Methods in Enzymology' ed. L. Grossman and K. Moldave Academic Press New York 1980 Vol. 65 p. 499. 10 A. J. H. Smith in 'Methods in Enzymology' ed. L. Grossman and K. Moldave Academic Press New York 1980 Vol. 65 p. 560. l1 F. Sanger A. R. Coulson B. G. Barrell A. J. H. Smith and B. A. Roe J. Mol. Biol.,1980 143,161. B.G. Barrell S.Anderson A. T. Bankier M. H. L. DeBruijn E. Chen A. R. Coulson J. Drouin I. C. Eperon B. A. Roe F. Sanger P. H. Schreier A. J. H. Smith R. Staden and I. G. Young Proc. Natl. Acad. Sci. USA,1980 77 3164. 312 M. J. Gait base-pairs the Sanger approach seems more adaptable for longer stretches of DNA because of the greater incorporation of radioactivity per nucleotide and this method will undoubtedly predominate in years to come as projects become yet more ambitious. Two very similar methods have been published for determining the sequence of tRNA and short ribosomal RNA that allow minor bases to be more easily identified. Both are based on the observation of Stanley and Va~silenko’~ that RNA can be partially hydrolysed under ‘single hit’ conditions by formamide or water to give two sets of fragments one of which contains 5‘-hydroxyl groups.These latter fragments can be 32P-labelled by the polynucleotide kinase reaction and fractionated by polyacrylamide gel electrophoresis to give a set of radioactive bands each differing in length by one nucleotide. In the new procedures the bands are transfer- red on to polyethyleneimine-cellulose’4or diethylaminoethyl-cellulosels plates and the polynucleotides are digested in situ with RNase T2 to release their 5’-terminal nucleosides as radioactive 3’,5’-diphosphates In the first method the diphosphates are chromatographed in unbuffered ammonium sulphate or ammonium formate solution (pH3.5),14 whereas in the latter method they are separated by electro- phoresis at pH 2.3.15 The nucleoside derivatives are identified by their mobility and the RNA sequence is ‘read off’ along the width of the plate.The sequences of other RNAs are most often determined via their complemen- tary DNA (cDNA) transcripts. Commonly this involves cloning of the DNA as described in last year’s Report; however this is not always necessary especially if specific DNA primers are available to select the species of RNA to be copied out of an impure mixture. The primers can be synthetic oligodeoxyribonucleotides16 (see also Section 3) or restriction fragments,” and the sequencing of the DNA is carried out by the Maxam-Gilbert method or by the ‘dideoxy’ approach. A novel alternative has recently been described where 32P-labelled oligoribonucleotides generated by digestion of the unknown RNA with RNase T followed by labelling of their 5’-ends are used to prime the DNA-polymerase-mediated synthesis of the second strand of DNA.Once again chain terminators are used to generate a series of DNA fragments that are resolvable by gel electrophoresis. The method has been used to obtain the sequence of 1060 bases at the 3’-end of poliovirus RNA.I8 3 Synthetic Oligonucleotides in Molecular Biology The use of synthetic oligonucleotides featured prominently in two approaches to the isolation of interferon cDNAs. Based on protein sequence information only the sequence of a pentadecadeoxyribonucleotidewas deduced. The oligonucleo- tide was found successfully to prime the reverse-transcriptase-mediated synthesis of the cDNA of human interferon p.The sequence of the cDNA was determined l3 J. Stanley and S. Vassilenko Nature (London) 1978,274 87. l4 K.Randerath R. C. Gupta and E. Randerath in ‘Methods in Enzymology’ ed. L. Grossman and K. Moldave Academic Press New York 1980,Vol. 65,p. 638. Is Y. Tanaka T. A. Dyer and G. G. Brownlee Nucleic Acids Res. 1980.8 1259. 16 G. G.Brownlee and E. M. Cartwright J. Mol. Biol.,1977 114 93; P. H. Hamlyn G. G. Brownlee C.-C. Cheng M. J. Gait and C. Milstein Cell 1978,15 1067. e.g. P.K.Ghosh V.B. Reddy M. Piatik P. Lebowitz and S.M. Weissman in ‘Methods in Enzymology’ ed. L. Grossman and K. Moldave Academic Press New York 1980,Vol. 65,p. 580 and references therein. N. Kitamura and E. Wimmer Proc.Natl. Acad. Sci. USA 1980 77 3196. Biological Chemistry -Part (ii)b Oligo- and Poly-nucleotides 313 directly without cloning and this information allowed further specific primers to be designed to obtain the remainder of the coding ~equence.~ In an alternative procedure several synthetic DNA primers were prepared based on all of the possible DNA sequences corresponding to part of the known protein sequence of interferon. A mixture of these oligonucleotides was used as a hybridization probe to screen cloned plasmid DNA containing interferon cDNA inserts. Under stringent conditions only the exactly matched probe hybridized thus enabling correct clone selectiom6 A colony-hybridization procedure involving synthetic oligo-deoxyribonucleotides has been used for screening clones containing genomic DNA19 and synthetic polymeric genes coding for poly(L-Asp-L-Phe).” A quick way of determining sequences adjacent to the 3’-poly(A) tail in mRNA has been described.Each of twelve dodecamers of the form d(pT,-N-N’) was used to prime the reverse-transcriptase-directed synthesis of cDNA corresponding to the mRNA of bovine growth hormone. Only the correctly matched sequence hybridized and acted as a primer.” Cloning and characterization of DNA sequences corresponding to RNA of the influenza virus has been facilitated by using a specific dodecadeoxyribonucleotide to prime the synthesis of cDNA at the 3’-end of the RNA.22 Although the influenza genome is segmented into eight separate RNA chains cloning of the entire genome is simplified in that all eight chains contain identical 3‘- and 5’-leader sequences.The use of this dodecamer and another oligonucleotide for the 5’-end of the cDNA to prime the DNA-polymerase-directed synthesis of the second DNA strand has greatly aided cloning of full-length cDNA.’~ The use of a specific oligodeoxyribonucleotideprimer is an essential element in the determination of DNA sequences cloned in bacteriophage M13 (see Section 2). A thirty-base cloned primer prepared by a combination of chemical and enzymatic synthesis has been shown to be extremely efficient in this respe~t.’~ When required it is isolated from plasmid DNA by digestion with restriction enzymes. A fully synthetic nonadecadeoxyribonucleotide has been shown to be of comparable value as a primer.25 A synthetic primer has the advantage that it may be prepared on substantially larger scale than a cloned primer.Of great potential is a recently described method for the directed deletion of intervening sequences (introns). A 21-unit oligonucleotide was synthesized that was complementary to the bases on either side of an intervening sequence of fourteen bases of a yeast tRNA gene contained in a plasmid. The intron was presumably looped out when the oligonucleotide was hybridized to the plasmid template. The oligonucleotide now acted as a primer for preparation of the second DNA strand in uitru and the heteroduplex was used to transform Escherichia coli l9 J. W. Szostak J. 1. Stiles B.-K. Tye P. Chiu F. Siterman and R.Wu in ‘Methods in Enzymology’ ed. R. Wu Academic Press New York Vol. 68,p. 419. 2o M. T. Doel M. Eaton E. A. Cook H. Lewis T. Patel and N. H. Carey Nucleic Acids Res. 1980 8,4575. 21 N. L. Sasavage M. Smith S. Gillam. C. Astell J. H. Nilson and F. Rottman Biochemistry 1980,19 1737. 22 A. R. Davis A. L. Hiti and D. P. Nayak Gene 1980,10,205. 23 G. Winter S. Fields M. J. Gait and G. G. Brownlee Nucleic Acids Res. 1981,9,237;M.Baez R. Taussig J. T. Zazra J. F. Young P. Palese A. Reisfeld. and A. M. Skalka ibid. 1980,8. 5845. 24 S. Anderson M. J. Gait L. Mayol and I. G. Young Nucleic Acids Res. 1980,8,1731. 25 S. A. Narang R. Brousseau H. M. Hsiung W. Sung R. Scarpulla G. Ghangas L. Lau B. Hess and R. Wu Nucleic Acids Res. Symp. Ser.No. 7 1980 377. 3 14 M. J. Gait cells. Clones with plasmid DNAs containing the deletion were selected by colony hybridization using radiolabelled synthetic oligonucleotides.26 X-Ray structural determination of crystals of self-complementary oligonucleo- tides has been an area of great activity in 1980. A major surprise was that both the hexanucleotide d(C-G-C-G-C-G)*’ and the tetranucleotide d(C-G-C-G),28 under conditions of high salt concentrations crystallized as similar but hitherto unknown left-handed double-helixes. This ‘Z-DNA’ differed from the B form not only in handedness but also in having twelve base-pairs per turn. Whereas the deoxycytidine residues had a conformation similar to that found in the B form the deoxyguanosine residues showed an unusual pucker of the deoxyribose ring and a high angle of rotation about the phosphate residue and the heterocyclic base was found to be in the ‘syn’rather than in the normal ‘anti’orientation.The Z-structure has also been found as an occasional form in fibres of p~ly[d(G-C)].poly[d(G-C)].~~ However it seems unlikely that the Z-structure has any physio-logical significance since it is formed only in solutions in which there are high salt concentrations. Moreover the self -complementary dodecamer d(C-G-C-G-A-A- T-T-C-G-C-G) was found to crystallize in a B form,30 suggesting that the Z-form is incompatible with other base sequences. 4 Synthesis of Oligonucleotides It is now almost universally agreed that chemical synthesis of oligonucleotides is best accomplished uia phosphotriester intermediates.Significant advances have been made recently in phosphorylation methods in the use of coupling agents and protecting groups and in solid-phase synthesis. When used in excess bifunctional 0-or p-chlorophenylphosphorodi-( 1,2,4-triazolide) (1) is effectively mon~functional,~~ and it swiftly phosphorylates the 3‘-hydroxyl group of a 5’-protected 2’-deoxyribonucleoside (2). The resultant monotriazolide (3) is a useful active intermediate (see Scheme 1).It is hydrolysed by water to give the corresponding 3’-aryl phosphate (4) which may be isolated as its triethylammonium or as its barium Alternatively the monotriazolide (3) may be allowed to react with 2-cyanoethanol in the presence of a catalyst such as N-methylirnida~ole~~*~~ to form the or of excess tria~ole~~ corresponding 3’-phosphotriester (5).The phosphotriester (5)may also be prepared from the aryl phosphate (4) by reaction with 2-cyanoethanol in the presence of a 26 R.B. Wallace P.F. Johnson S. Tanaka M. Schold K. Itakura and J. Abelson Science 1980,209,1396. ” A. H.-J. Wang G. J. Quigley F. J. Kolpak J. A. Crawford J. H. van Boom G. van der Marel and A. Rich Nature (London) 1979,282,680. H. Drew T. Takano S. Tanaka K.Itakura and R. E. Dickerson Nature (London) 1980 286 567; J. L. Crawford F. J. Kolpak A. HA. Wang G. J. Quigley J. H. van Boom G. van der Marel and A. Rich Proc. Natl. Acad. Sci. USA 1980,77,4016. *’ S. Arnott R. Chandrasekaran D. L. Birdsall A. G. W. Leslie and R.L. Ratliff. Nature (London) 1980,283,743. 30 R. Wing H.Drew T. Takano C. Broka S. Tanaka K. Itakura and R. E. Dickerson Nature (London) 1980,287.755. 31 J. B. Chattopadhyaya and C. B. Reese Tetrahedron Lett. 1979,5059. 32 G. R. Gough K. J. Collier H. L. Weith. and P. T. Gilham Nucleic Acids Res. 1979 7 1955. 33 P. Cashion K. Porter T. Cadger G. Sathe T. Tranquilla H. Notman and E. Jay Tetrahedron Lett. 1976,3769. 34 C. Broka T. Hozumi R. Arentzen and K. Itakura Nucleic Acids Res. 1980 8 5461. 35 M. J. Gait S. G. Popov M. Singh and R. C. Titmas Nucleic Acids Res. Symp. Ser. No. 7,1980,243. Biological Chemistry -Part (ii)b:Oligo-and Poly-nucleotides 0 I "'7 O=P-N I bN 0 Cl(o-or p-) 0 I O=P-OCH,CH,CN I 0 Cl(o- or p-) B =Thy 6-N-PhCO-Ade 4-N-PhCO-Cyt or 2-N-isobutyryl-Gua (MeO)2Tr = dimethoxytrityl Reagents i (1);ii H20; iii HOCH2CH2CN;iv HOCH2CH,CN coupling agent; v Et,N; vi H' Scheme 1 316 M.J. Gait coupling agent. After detritylation under acidic conditions the 5‘-hydroxy-compound (6) may then be coupled with the aryl phosphate (4) to give fully protected dinucleotides. All sixteen of these have been prepared via the barium salt route in good yield.’* The reaction of the phosphomonotriazolide (3)with the hydroxy- compound (6) also gives a din~cleotide.~~ In another variation the phosphotriester (3)may be prepared directly from the 2-deoxynucleoside derivative (2) by reaction with 0-or p-chlorophenyl phosphorodichloridite in tetrahydrofuran at -78 “C followed by addition of 2-cyanoethanol and then oxidation with iodine in water.36 During phosphorylation reactions involving 2-N-protected deoxyguanosine derivatives 0-6-phosphorylation of the guanine moiety is possible depending on the choice of solvent and of basic catalyst.This side-reaction is supposedly reversible by treatment with aqueous ~yridine,~~.” but an irreversible modification of guanine has been obtained in at least one case,34 and the formation of inter-nucleotide bonds by this route clearly requires great care. In the case of 6-N-benzoyl-2‘-deoxyadenosine derivatives there is great danger of loss of N-benzoyladenine during acidic removal of 5’-dimethoxytrityl groups. Reagents of choice for this reaction are conventionally benzenesulphonic acid in chloroform-methanol (7 :3)38 or more recently trichloroacetic acid in chlor~form’~ or zinc br~rnide.’~ A saturated solution of this latter reagent in nitromethane has been used as a deprotecting agent in the solid-phase synthesis of oligodeoxyribo- n~cleotides.~’No depurination was observed during the deprotection steps.The reaction mechanism is thought to involve chelation between the Lewis acid and the 1’-endocyclic and 5’-exocyclic oxygen atoms of the deoxyribose moiety. l-(Mesitylene-2-sulphonyl)-3-nitro-1,2,4-triazole(MSNT) (7a)41 and 1-(2,4,6- tri-isopropylbenzenesulphonyl)-3-nitro-l,2,4-triazole(TPSNT) (7b)42 are new coupling agents that are useful for the rapid formation of inter-nucleotide bonds. Although rates of are slightly lower than for the corresponding tetrazole derivatives which have hitherto been popular,38 there are fewer side-reacfion~.~~ Uracil and 2-N-benzoylguanine residues are particularly susceptible to modification.For example MSNT has been shown to react with 2’,3’,5’-tri-O-acetyluridineand 2-N-benzoyl-3’,5’-di-O-acetyl-2’-deoxyguanosine to give (8) and (9) respectively. Fortunately these modifications are reversible by mild alkaline treatment. Base modification by arenesulphonyl-tetrazolesis faster and more complex.41 Much debate has centred also on the amount of unwanted 5’-0-sulphonation that is caused by arenesulphonyl-azolides during coupling reactions. Whereas arenesulphonyl-tetrazoles and l-arenesulphonyl-3-nitro-1,2,4-triazoles are undoubtedly powerful sulphonating agents in the absence of a phosphodiester component the amount of sulphonated product obtained under coupling conditions 36 D.Molko R. B. Derbyshire A. Guy A. Roget and R. Teoule Tetrahedron Lett. 1980,21 2159. 37 H. P.Daskalov M. Sekine and T. Hata Tetrahedron Lett. 1980.21 3899. W. L. Sung H. M. Hsiung R. Brousseau J. Michniewicz R. Wu and S. A. Narang Nucleic Acids Res. 1979,7,2199. 39 M. D.Matteucci and M. H. Caruthers Tetrahedron Lett. 1980 21 3243; V.Kohli H. Blocker and H. Koster ibid. p. 2683 40 M. H. Caruthers S. L. Beaucage J. W. Efcavitch E. F. Fisher M. D. Matteucci and Y. Stabinsky Nucleic Acids Res. Symp. Ser. No. 7 1980,215. 41 C.B. Reese and A. Ubasawa. Tetrahedron Lett. 1980,21,2265. 42 J. F.M.de Rooij G. Wille-Hezeleger P. H. van Deursen J. Serdijn and J. H. van Boom Recl. Trao. Chim. Pays-Bas 1979,98,537. 317 Biological Chemistry -Part (ii)b Oligo- and Poly-nucleotides SO* R (7)a; R = Me b R = Pr’ OAc OAc (8) 0 RO-P-N I 0 N=N Cl(o-or p-) OAc (9) is effectively very small when the nucleoside phosphodiester derivative is aryl rather than alk~l~~ and when the concentration of coupling agent is not excessive.43 In the case of arenesulphonyl-tetrazoles the major phosphorylating intermediate in coupling reactions is thought to be the tetrazole derivative Two alternative phosphate-protecting groups have been proposed which in contrast to aryl groups may be removed by reactions that do not involve nucleophilic attack at the phosphorus atom.The p-nitrophenylethyl group is removed by DBU (1,8-diazabicyclo[5.4.0]undec-7-ene)or DBN (1,5-diazabicyclo[4.3.0]non-5-ene) via a p-elimination me~hanism.~~ The methyl group is removed by t-b~tylamine~’ or by thiophenol and trieth~lamine.~~ However since both these protecting groups are alkyl esters the use of arenesulphonyl derivatives as coupling agents for the formation of inter-nucleotide bonds would not be recommended in these cases (see above). Methyl seems particularly suited as a protecting group when a ‘phosphite triester’ coupling procedure is used. This route was originally proposed for thymidyl oligomers in 1975.49A 5’-protected 2’-deoxynucleoside is allowed to react with an alkyl or aryl phosphorodichloridite in tetrahydrofuran at -78 “C,in the presence of a hindered base.The product is allowed to react (without isolation) with a second 43 M. J. Gait and S. G. Popov Tetrahedron Lett. 1980.21 2841. A. Kraszewski J. Stawinski and M. Wiewiorowski Nucleic Acids Res. 1980,8 2301. D. G. Knorre and V. F. Zarytova in ‘Phosphorus Chemistry directed towards Biology’ ed. W. J. Stec Pergamon Press 1980,p. 13. 46 E. Uhlman and W. Pfleiderer TetrahedronLett. 1980.21. 1181. 47 D. J. H. Smith K. K. Ogilvie and M. F. Gillen. TetrahedronLett. 1980,21. 861. G.W.Daub and E. E. van Tamelen J. Am. Chem. Soc. 1977,99,3526. 49 R.L.Letsinger and W. B. Lunsford J. Am. Chem. SOC. 1975.97.3655. 318 M. J. Gait deoxynucleoside unit to give the dinucleoside phosphite triester which may be oxidized to the corresponding phosphotriester by its reaction with iodine in water (see Scheme 2).This method has now been extended for general use in oligodeoxyribonucleotidesynthesis," where it is claimed that there is much less tendency for side-reactions to occur particularly those involving the heterocyclic bases. OH 0 I P-CI I OR \ xoPxoP' 0 0 I I OY OY Reagents i ROPCI, THF at -78°C; ii (11);iii I, H,O Scheme 2 Developments in the oligoribonucleotide field have paralleled those of the deoxy- series. An excellent assembly of a decaribonucleotide corresponding to the 3'-terminus of yeast tRNAA'" has been de~cribed.~~ The methoxytetrahydropyranyl group was used for protection of the 2'-hydroxyl group and inter-nucleotide phos- photriester bonds were formed rapidly and in high yield using MSNT as the coupling agent.5'-0-Sulphonation was not observed during the coupling steps. An added point of interest is that the 5'-hydroxyl component in each coupling reaction contained an unprotected 3'-hydroxyl group. Not only is the rate of formation of 3'-3' linkages considerably slower but they are also extremely prone to alkaline hydrolysis at rates more than three orders of magnitude faster than for the corres- ponding 3'-5' linkages.52 In contrast oligoribonucleotide assembly involving the use of the 2,2,2- trichloroethyl protecting group for phosphate and the t-butyldimethylsilyl group for protection of the 2'-hydroxyl gave poor yields in the coupling steps when arenesulphonyl-azolides were used as coupling agents.53 Much greater success was 50 J.L. Finnan A. Varshney and R. L. Letsinger Nucleic Acids Res. Symp. Ser. No. 7 1980 133. 51 S. S. Jones B. Rayner C. B. Reese A. Ubasawa and M. Ubasawa Tetrahedron 1980,36,3075. 52 B. Rayner C. B. Reese and A. Ubasawa J. Chem. SOC. Chem. Commun. 1980,972. 53 K. K. Ogilvie and R. T. Pon Nucleic Acids Res. 1980,8 2105. Biological Chemistry -Part (ii) b Oligo- and Poly-nucleotides 3 19 obtained by using this combination of protecting groups when the phosphite triester coupling procedure was although the methyl group is now preferred for phosphate protection (see above).47 Considerable progress was made during 1980 in solid-phase synthesis of oligo- nucleotides especially due to the use of phosphotriester coupling methods.In the phosphodiester route the only successful syntheses had made use of relatively polar supports such as polyamide resins. In contrast a number of different supports have found utility in oligonucleotide synthesis via phosphotriester intermediates viz. p~lydimethylacrylamide,~~ cellu-polyacryloylmorpholide,56~57poly~tyrene,~**~~ lose,6o and ~ilica.~’.~~ Several of the routes for synthesis of oligodeoxyribonucleo- tides relied on sequential coupling of 5’-O-dimethoxytrityl-2’-deoxynucleoside 3’-arylphosphates or corresponding di- or tri-nucleotide derivatives (in pyridine in the presence of arenesulphonyl-azolides) to deoxynucleoside derivatives that were joined to the support via an alkali-labile 3’-0-~uccinate~~*~~*~~ or 3’4-~hthalate~~ linkage (see Scheme 3).Oligodeoxyribonucleotidesup to 21units long 0 0 I I o=p-o-0 I I 0 c=o I CH, I CH,CNH-II C1(o-or 0 CH, I CH,~NH-@ II (MeO)2Tr= dimethoxytrityl 0 Reagents i coupling agent pyridine Scheme 3 have been prepared by this Yields approached those obtained by comparable solution methods. It has been observed that in the case of polystyrene resins the yields in the first coupling steps were unusually poor.63 However consistently high yields were obtained with polystyrene that was suspended in tetrahydrofuran using a stepwise phosphorylation approach involving addition of 54 K.K.Ogilvie and M. J. Nemer Can. J. Chem.1980 58 1389. ” M. J. Gait M. Singh. R. C. Sheppard M. D. Edge A. R. Greene G. R. Heathcliffe. T. C. Atkinson C. R. Newton and A. F. Markham Nucleic Acids Res. 1980 8 1081. 56 K.Miyoshi. T. Huang and K.Itakura Nucleic Acids Res. 1980,8,5491. 57 K.E. Norris F. Norris and K.Brunfeldt Nucleic Acids Res. Symp. Ser. No. 7 1980 233. K.Miyoshi and K.Itakura Nucleic Acids Res. Symp. Ser. No. 7 1980,281. 59 V. N. Dobrynin B. K.Chernov and M. N. Kolosov Bioorg. Khim. 1980,6 138. 6o R. Crea and T. Horn,Nucleic Acids Res. 1980,8 2231. 61 K.K.Ogilvie and M. J. Nemer. Terrahedron Leu. 1980 21 4159. 62 A. F. Markham M. D. Edge T. C. Atkinson A. R. Greene G. R. Heathcliffe C. R. Newton and D. Scanlon Nucleic Acids Res. 1980,8 5193. 63 K.Miyoshi R. Arentzen T. Huang and K.Itakura Nucleic Acids Res. 1980,8 5507. 320 M. J. Gait compounds of type (3) in the presence of 4-(dimethylarnin0)pyridine.~*Similarly good coupling yields have been obtained by use of the phosphite triester route using silica-gel supports. These may be used in a flow system of operation. Oligodeoxyribonucleotidesup to thirteen units long4’ and oligoribonucleotides up to six units long61 have been prepared. At least in the case of oligodeoxyribonucleo- tides solid-phase synthesis has now emerged as the most efficient method for preparations on a scale suitable for most biological applications (i.e. up to a few milligrams). Two reviews on solid-phase synthesis of oligonucleotides have been published.64 Two useful mass spectral methods have been described for the analysis of protected oligodeoxyribonucleotides containing phosphotriester linkages.Use of pyrolysis-mass spectrometry has allowed characteristic ions of the protected bases and terminal substituents to be Much less destructive is 252Cf plasma desorption mass spectrometry. The molecular weight of large fragments of oligo- nucleotides can be determined and this has been used for sequence analysis of protected intermediates up to hexanucleotides.66 The ions Pb2+ and Zn” are efficient catalysts for the poly(C)-directed polymeriz- ation of an activated guanylic acid derivative guanosine 5’-phosphoroimidazolide to give oligomers up to 40 units long. When Pb2+ was the catalyst 2‘-5’ linkages predominated whereas 3’-5‘linkages were mostly formed in the presence of Zn2’ ion6’ In contrast the Pb2’-catalysed polymerization of adenosine 5‘-phosphoro- imidazolide using poly(U) as a template gave preferentially 3’-5’linkages.68.5 Analogues of Oligo-and Poly-nucleotides Poly(5-ethynyluridylic acid) prepared by enzymatic polymerization of 5-ethynyl- uridine 5‘-diphosphate has an unusually stable secondary structure with a T of 76°C. It forms a 1:l complex with poly(A) that has a T of 78”C which is considerably higher than that of the unsubstituted duplex poly(U) -p~ly(A).~~ Although 8-azidopurine mononucleotides have been used effectively as photo-affinity reagents the corresponding homopolymers have not yet been prepared because the syn conformation of the nucleoside makes enzymatic polymerization difficult.Copolymers of poly(A,8-azidoadenylic acid) have recently been prepared however. Those with low 8-azido-Ade content formed 1 2 complexes with poly(U). It is believed that the azidopurine nucleotides are constrained intrahelically and possibly adopt the anti conformation. The copolymers have been used to study the subunit topology of RNA polymerase from E. coli.” An analogue of (U)4,where the inter-nucleotide linkages are replaced by 3’-5‘ phosphite esters has been prepared via the corresponding 2,2,2-trichloroethyl 64 M. J. Gait in ‘Polymer-supported reactions in Organic Synthesis’ ed. P. Hodge and D. C. Sherrington John Wiley 1980,p. 435;N. K.Mathur C. K.Narang and R. E. Williams ‘Polymers as aids in Organic Synthesis’ Academic Press 1980,p.81. J. Ulrich M.T. Bobenrieth R. Derbyshlre F. Finas A. Guy F. Odin M. Polverelli and M. Teoule 2. Nuturforsch. Teil. B 1980,35,212. 66 C. J. McNeal S. A. Narang R. D. Macfarlane H. M. Hsiung and R. Brousseau Roc. Nut/. Acud. Sci. USA 1980,77,735. 67 R. Lohrmann P.K. Bridson and L. F. Orgel. Science 1980,208. 1464. H. Sawai Nucleic Acids Res. Symp. Ser. No. 8 1980,77. 69 E.Biala A. S.Jones and R. T. Walker Tetrahedron 1980.36,155. ’O I. L. Cartwright and D. W. Hutchinson Nucleic Acids Res. 1980,8 1675. Biological Chemistry -Part (ii)b Oligo- and Poly-nucleotides 321 phosphite triester~.~~ These latter compounds are useful intermediates also. Reac- tion with iodine and a primary alkylamine gives the corresponding alkyl-phos- phoramidate.Alternatively reaction with selenium or sulphur gives the phos- phoroselenate or phosphorothioate re~pectively.~~ Similar analogues containing 2,2,2-trichloroethyl phosphite triesters have been prepared in the deoxy-~eries.~~ A number of dinucleoside phosphates containing acyclic analogues of 2’-deoxyadenosine and 2‘-deoxythymidine which lack the 2’-methylene of the sugar have also been ~ynthesized.~~ A comprehensive review of synthetic analogues of nucleic acids has been p~blished.~’ 6 Chemical Reactions on Polynucleotides Formaldehyde undergoes two different reactions with nucleic acids and their com- ponents. In aqueous solution a rapid and reversible one causes the hydroxymethyla- tion of imino- and amino-groups. A slower reaction results in formation of cross-links.Cross-linked nucleosides have now been isolated from formaldehyde-treated RNA and DNA and it has been confirmed that the cross-links are methylene bridges exclusively between exocyclic amino-groups of Cyt Gua and Ade.76 2’,3’- 0-Isopropylidene-adenosine -cytidine and -guanosine react with aqueous formal- dehyde in ethanol to give the corresponding N-ethoxymethyl derivatives which are more stable than their N-hydroxymethyl counterparts. N-Ethoxymethylation may prove useful for base-modification of single-stranded regions of nucleic Two classic pyrimidine-specific reactions have been proposed as alternatives to treatment with hydrazine for the Maxam-Gilbert procedure for sequencing DNA. Potassium permanganate preferentially oxidizes the 5-6 double-bond of thymine residues and hydroxylamine hydrochloride preferentially adds across the 5-6 double-bond of ~yfosines.~~ The reaction of DNA with a mixture of methoxyamine and sodium bisulphite also causes modification of cytosine residues.Base-pairing is disrupted and the effect of secondary structure on the mobility of DNA fragments in gels is eliminated. This reaction has been useful in the ‘dideoxy’ method of DNA seq~encing.~’ DNA may be labelled at its 3’-end to high specific activity by addition of [a-32P]cordycepin 5’-triphosphate the reaction being catalysed by terminal trans- ferase. The labelled DNA is now resistant to degradation by 3’-exonu~lease.~~ Two chemical reagents have been used to probe the secondary and tertiary interactions of RNA.Dimethyl sulphate alkylates the N-7 position of guanosines and the N-3 position of cytidines; diethyl pyrocarbonate carbethoxylates the N-7 position of adenines. However the reactions only occur if sites are not involved in structural interactions. 32P-Labelled RNA chains may be broken at the base- 71 K. K. Ogilvie and M. J. Nemer Tetrahedron Lett. 1980 21 4145. 72 M. J. Nemer and K. K. Ogilvie Tetrahedron Lett. 1980,21,4149. 73 B. P.Melnick J. L. Finnan and R. L. Letsinger J. Org. Chem. 1980,45 2715. 74 K. K. Ogilvie and M. F. Gillen. Tetrahedron Lett. 1980 21 327. 75 A. S.Jones Int. J. Biol. Macromol. 1979 1 194. 76 Y.F. M. Chaw L. E. Crane P.Lange and R. Shapiro Biochemistry 1980,19,5525. 77 P. K.Bridson J.Jirickny 0.Kemal and C. B. Reese J. Chem. SOC. Chem. Commun. 1980 208. 78 C. M. Rubin and C. W. Schmid Nucleic Acids Res. 1980,8,4613. 79 N. S.Ambartsumyan and A. M. Mazo FEBSLett. 1980,114,265. C.-P. D. Tu and S. N. Cohen Gene 1980,lO. 177. 322 M. J. Gait modified sites and the fragments separated on polyacrylamide gels to locate the positions of modification. Probing reactions carried out at different temperatures have been used in parallel with chemical sequencing reactions to locate regions of higher-order structure in tRNA.8’ Some useful reagents for RNA-RNA and RNA-protein cross-linking have been described. Like other glyoxal-type reagents N-acetyl-N-(p-glyoxylylbenzoy1)-cystamine reacts with guanine and arginine derivatives to give acid-stable adducts.Reduction of the disulphide bonds liberates free thiol groups which can be used as sites for cross-linking to RNA or protein.82 Adenines and cytosines react rapidly below pH 6 with p-nitrophenyl or N-hydroxysuccinamido 3-(4-bromo-3-oxo- butanesulphony1)propionateat the a-halogenocarbonyl moiety. At a higher pH the activated carboxylic acid may then be used for acylation of proteins.83 The mechanism of binding of the anti-cancer drug ci~-[Pt(NH~)~Cl~l to DNA is the subject of much intense investigation. Recent evidence suggests that the drug binds selectively to (dG) (dC) sequences (n s 4). A model involving intra-strand cross-linking via co-ordination of the platinum to the N-7 positions of adjacent guanines is Another report suggests that such co-ordination could result in unusual Gua-Gua mi~pairing.~’ N.m.r.and X-ray structural studies of crystals of short duplexes that are currently under way should clarify the situation. Mechan- isms of reaction between chemical carcinogens and nucleic acids have been well reviewed recently.86 D. A. Peattie and W. Gilbert Proc. Natl. Acad. Sci. USA 1980,77,4679. ’* A. Expert-Bezancon and D. Hayes Eur. J. Biochem. 1980,103,365. 83 G. Fink H. Fasold W. Rommer and R. Brimacombe Anal. Biochem. 1980,108 394. 84 G. L. Cohen J. A. Ledner W. R. Bauer H. M. Ushay C. Caravana and S. J. Lippard J. Am. Chem. SOC.,1980,102,2487. ” R. Faggiani C. J. L. Lock and B. Lippert J. Am Chem. Soc. 1980,102 5418. 86 D. E. Hathway and G. F. Kolar. Chem.SOC. Rev. 1980,9,241.

ISSN:0069-3030    

DOI:10.1039/OC9807700310

出版商:RSC    

年代:1980

数据来源: RSC

摘要:

15 Biological Chemistry Part (iii) Peptides By C. E. DEMPSEY and C. A. VERNON Department of Chemistry University College London 20 Gordon Street London WC1 OAJ Introduction.-The words ‘peptides’ and ‘proteins’ are used for compounds of the same chemical type i.e. those polymers consisting of amino-acids that are joined together through so-called peptide bonds. The distinction is usually made on the basis of size compounds containing less than about seventy amino-acid residues are called peptides whereas those with more are called proteins. The distinction is not entirely arbitrary since soluble proteins when subjected to high temperatures or extremes of pH undergo what is known as gross denaturation; i.e. they change their tertiary structure become insoluble and lose all biological activity.Small peptides do not show this phenomenon. This is not to say that peptides do not have preferred conformations in solution or that these conformations are not important in their biological activity. Nevertheless they are much more robust chemically and will withstand extremes of temperature and pH which would certainly denature proteins. Obviously there is no sharp point of discontinuity the decision as to the number of residues above which the word ‘protein’ rather than ‘peptide’ is used is largely a matter of individual taste. In this review we shall call peptides those compounds with up to seventy amino-acid residues. The literature on peptides is now vast and the number of papers on the subject grows yearly.During 1980many thousands of papers on various aspects of peptides appeared and the present reviewers can only refer to a relatively small number of them. We have made our selection on what we believe to be important but we must emphasize that this inevitably involves personal bias. It is worth enquiring as to why so much effort is currently devoted to the study of peptides. The answer is that they show a wide variety of biological activities if they were biologically inert it is doubtful if any chemist would bother with them. Biologically active peptides can be divided (somewhat arbitrarily) into three groups first the hormones. It has been known for many years that many hormones are peptides and the ‘classical’ ones (vasopressin oxytocin insulin glucagon ACTH etc.) have been extensively studied.Work on these still proceeds apace better methods of synthesis of the native peptides and of analogues crystallographic and n.m.r. studies and experiments designed to give more information about how they exert their effects are all being actively pursued. In recent years other peptide hormones have been discovered (the gastrin family being a case in point) and no doubt others will be reported in the future. Secondly several groups of endogenous 323 324 C. E. Dempsey and C.A. Vernon peptides with profound biological effects have been found; for example vasoactive intestinal peptide (VIP) the enkephalins and the endorphins. The functions of these peptides are still matters of dispute (sometimes of vigorous dispute) but of their importance there can be no doubt.Thirdly a large number of exogenous peptides derived from such diverse sources as animal venoms amphibian skins etc. have been discovered which have profound pharmacological effects in mam- malian organisms. These peptides provide powerful tools in the investigation of normal biological processes. It has also become apparent that many peptides are biosynthesized as inactive precursors having an extended polypeptide chain attached to the N-terminal residue of the active peptide. These extended chains are removed prior to or during secretion and the enzymes responsible (as well as the biological significance of these processes) are currently being actively pursued. In the peptide field it is very difficult to separate the various chemical and biological aspects which make up any given investigation.In so far as we can do so however we shall discuss recent work under the headings (1) synthesis (2) isolation of naturally occurring peptides (3) methods of sequence determination (4) physical studies (5) endogenous peptides; occurrence and functions and (6) exogenous peptides derived from animal venoms and other sources. Because of limitations of space we shall exclude those peptides that contain abnormal amino- acids. Such peptides are found largely (but not exclusively) in bacteria algae fungi and certain higher plants and they appear to be biosynthesized by a process that does not involve the normal genetic coding mechanism. 1 Synthesis Apart from intrinsic interest the impetus in this field arises from the need to synthesize naturally occurring peptides that are of importance in biological investi- gations or in clinical medicine and which occur either in very small amounts or in tissues that are difficult to obtain in sufficient quantity.Furthermore there is a need for analogues and although these can sometimes be made by modification of natural peptides synthesis is clearly the preferred route. A recent book provides a detailed account of the present state of the art and of the various strategies which can be adopted.’ Classical Solution Methods.-These methods go back to the time of Fischer and of Curtius and entail the condensation of suitably protected amino-acids to give protected dipeptides which can then (after suitable manipulation) be further con- densed to give tripeptides and so on.A common strategy for large peptides is to make a small number of segments and to condense these together in the final steps. The advantage of the method is that each intermediate can be purified before the next condensation cycle hence minimizing heterogeneity in the final product. The disadvantages are that the procedure is slow (and tedious) and more importantly that protected peptides (particularly larger ones) tend to be insoluble; this may prevent further condensation and especially the condensation of large segments. I ‘The Peptides. Analysis Synthesis Biology’ Vol. 2 ed. E. Gross and J. Meienhofer; Academic Press New York,1979. Biological Chemistry -Part (iii) Peptides 325 A number of strategies have been evolved to avoid these problems and full discussions of these are available.2 A great deal of effort has been devoted to the correct choice of protecting groups coupling reagents and methods of deprotection.A survey devoted largely to such matters was dealt with in Annual Reports for 1978.3In this Report we shall deal with only a small number of recent syntheses that used classical solution methods. A new method of forming N-protected amino-acids uses 3,5-di-t-butyl-4-biphenyl01(l),and involves the anodic oxidation of this reagent in dichloromethane in the presence of the free amino-acid esters4 Oxidation to a phenyloxylium ion occurs and this condenses with nucleophiles to form p-quinol derivatives as shown in Scheme 1.The protecting group (3,5-di-t-butyl-4-oxo-l-phenylcyclohexa-2,5-dienyl; PChD) can be removed quantitatively either by treatment with trifluoroacetic acid (50%) in dichloromethane at 25 "Cor by a hydrogenolytic reaction using a palladium catalyst in methanol. - 0 Bu'QBu'+ H,NCR'R2C02R3 -2e- Bu' -2H' Ph (1) Scheme 1 Ph NCR'R2C0,R3H The authors tested the use of their protecting group by synthesizing the simple peptide Pro-Leu-Gly-NH2 by the route shown in Scheme 2. Removal of the protecting group gave the tripeptide which was said to be chromatographically pure and racemate-free (although no details supporting either statement are given). The peptide is an inhibitor of melanocyte-stimulating hormone (MSH).PChD-Leu + Gly-NH2 5 PChD-Leu-Gly-NH2 Leu-Gly-NH2 1iv PChD-Pro-Leu-Gly-NH2 Reagents i DCC (dicyclohexylcarbodi-imide) HOBt (1-hydroxybenzotriale); ii deprotection; iii hydrogenolysis; iv PChD-Pro DCC HOBt Scheme 2 The 9-fluorenylmethyloxycarbonyl (Fmoc) group has been much used for the protection of the a-amino-function in peptide synthesis. It has the advantage that it can be removed under very mild basic conditions but is quite resistant to acidolysis. It has been widely used in solid-state synthesis. It has now been investigated as a suitable protecting group for stepwise chain-lengthening in soluti~n.~ The essential strategy is to use the p-nitrophenyl esters of Fmoc-protected amino-acids as acylat- ing agents. The sequence shown in Scheme 3is illustrative.Coupling was repeated (a) M. Mutter and E. Bayer in ref. 1. p. 286; (6)I. Ugi in ref. 1 p. 365. P. M. Hardy Annu. Rep. hog. Chem.. Sect. B. 1978,75 370. M. H. Khalifa G. Jung and A. Rieker Angew. Chem. Inf.Ed. Engl. 1980 19 712. ' A. Bodanszky M. Bodanszky N. Chandrarnouli J. Z. Kwei J. Martinez and J. C. Tolle J. Org. Chem. 1980,45,72. C. E. Dempsey and C.A. Vernon Z-Val-Leu + Thr(Bu')-OMe A Z-Val-Leu-Thr(Bu')-OMe 1ii-iv Fmoc-Ser(Bu')-Val-Leu-Thr(Bu')-NH2&Val-Leu-Thr(Bu')-NHz (Z-= benzyloxycarbonyl) Reagents i DCC HOBt; ii purification; iii arnmonolysis; iv hydrogenation; v Fmoc-Ser(Bu')-ONp (-ONp = p-nitrophenoxy) Scheme 3 using successively the p-nitrophenyl esters of Fmoc-Asn Fmoc-Leu and Fmoc- Tyr(Bu') to give the final protected peptide (2) in (so the authors claim) good yield and homogeneous form.The amino-acid sequence is in fact the C-terminal sequence of vasoactive intestinal peptide (VIP) from chicken. There seems no reason why larger chains should not be synthesized by this route. Fmoc-Tyr(Bu')-Leu-Asn-Ser(Bu'j-Val-Leu-Tr(But)-NHz (2) An interesting piece of work which employed synthetic sequence and immuno- logical techniques to solve a structural problem has been reported by the Liverpool peptide group,6 working in conjunction with a group in M~nich.~ The background is as follows it has been known for some years that the naturally occurring peptide gastrin (which has a regulatory function in the gut it stimulates secretion of gastric acid and alters gut motility and the tone of certain sphincters) contains seventeen amino-acid residues.It has also been known that a larger precursor (big gastrin) can be isolated and that this contains thirty-four residues. The human peptides are designated hG17 and hG34 respectively. The sequence of hG34 was given as shown in (3) in which residue 1 is pyroglutamic acid; conversion of hG34 into hG17 occurs largely by cleavage on the carboxyl side of Lys-17 (liberating two fragments one of which is hG17 and free lysine). The peptide corresponding to the sequence shown in (3)was synthesized and shown to have identical chromatographic proper- ties to hG34 and to be equally effective in promoting the secretion of gastric acid.Such criteria would normally be taken to mean that the sequence shown in (3) is certainly correct. However it was found to be possible to raise an antiserum to hG34 which was highly specific for the N-terminal region. This antiserum reacted differently with the native and synthetic peptides and it became clear that the sequence of residues shown in (3) must contain at least one error. The sequence was studied again using a micro-technique. Residue 1 was unblocked using a specific pyroglutamyl aminopeptidase and Edman degradation was then performed 61 PGlu-Leu-Gly-Pro-Gln-Gly-H~s-Pro-S~r-Leu-Val-Ala-Asp-Pro-Ser-Lys--I.&Gln-Gly-Pro-Trp-Le~(-Glu)~-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2 (3) 'A. M. Choudhury G. W. Kenner S. Moore K.L. Ramachandran W.D. Thorpe R. Ramage G. J. Dockray R. A. Gregory L. Hood and M. Hunkapiller Hoppe-Seyler's Z. Physiol. Chem. 1980,361 1719. ' E.Jaeger M. Gemeiner W. Goehring S. Knof R. Scharf P. Thamm G. Wendelberger and E. Wiinsch Monatsh. Chem. 1980,111,125. 327 Biological Chemistry -Part (iii) Peptides using an automated Beckman (890B) sequenator. The detection of phenylthiohy- dantoin derivatives was made by a sensitive high-performance liquid chromato- graphic technique. It was found that the correct sequence of hG34 has -Pro- at position 7 (instead of -His-) and -His- at position 9 (instead of -Ser-). Not content with this the two groups went on to synthesize the nonadecapeptides corresponding to residues 1-19 of the original and the revised sequences.Synthesis was by conventional solution methods and led to fragments 1-6 7-12 and 13-19. These fragments were coupled and deprotected. Neither peptide (as expected) had any activity in stimulating secretion of acid but whereas the peptide corresponding to the revised sequence of big gastrin had full immunological activity towards an antiserum that was known to be directed towards residues 4-9 the peptide corresponding to the original sequence was 1000 times less active. This very fine piece of work illustrates a number of problems in the peptide field not least of which is the difficulty of relying on chromatographic techniques to establish identity even when these are backed up by a biological test. A series of papers by a Dutch group has appeared on the synthesis of fragments of human P-lipotropin.Although other syntheses of such fragments have been reported these papers are worthy of comment because of the deliberate choice of the classical fragment-condensation method the strategy adopted and the care exercised in characterization of the final products. P-Lipotropin is a protein that contains 91 amino-acid residues and which can be isolated from the pituitary bodies of many species. It has biological activity of its own but one of its most interesting features is that it contains the sequence of P-MSH (p-melanocyte-stimulating hormone; sequence 41-58) a fragment of ACTH (adrenocorticotropin; sequence 47-53) a-endorphin (sequence 61-76) y-endorphin (sequence 6 1-77) and P-endorphin (sequence 61-91).The endorphin family of peptides possess activity resembling that of morphine and are sometimes called opiate peptides. It seems probable that they arise by cleavage from P-lipotropin. 61 77 Tyr-Gly-Gly-Phe-Met-Thr-Ser-Glu-Lys-Ser-Gln-Thr-Pro-Leu-Val-Thr-Leu The sequence of human y-endorphin is (4) where the numbers refer to the sequence of P-lipotropin. a-Endorphin differs by deletion of Leu-77. Protected fragments 6 1-69 and 70-77 were synthesized using conventional reagents and condensed and deprotected as shown in Scheme 4.8 The final peptide was subjected Boc-(6149)-OMe Z-( 70-7 7) -OBU' ii 'J. B0~-(6149) + (70-77)-OBut iii J. Boc-(61-77)-OBuf Ay-endorphin Reagents i NaOH at room temperature; ii HZ,Pd/C DMF; iii DCC HOBt; iv trifluoroacetic acid (TFA) Scheme 4 W.A. A. J. Bijl J. W. van Nispen and H. M. Greven Red. Trav. Chim. Pays-Bas 1979,98,571. 328 C.E. Dempsey and C. A. Vernon to column chromatography using silica and was then found to be homogeneous on t.l.c. to have 91.7% of main component on h.p.l.c. and to be racemate-free. This latter finding was established by treating the acid hydrolysate with L-amino-acid oxidase (LAO),which is specific for amino-acids of the L configuration. &Endorphin was synthesizedg by an essentially similar procedure and the final product was subjected to the same rigorous criteria of purity. The choice of classical fragmentation methods in the work described by the Dutch workers arose because they wished to test appropriate fragments for biologi- cal activity.They were also able to check the extent of racemization at every stage. Although it has long been known that racemization can occur in peptide synthesis it is not easy to predict its extent in any given step. Ideally it should always be investigated experimentally (by for example the LAO method). A cautionary instance occurred during the synthesis of a-endorphin. Coupling of Z-Leu-Val with Thr-Leu-OBu' by the DCC/HOBt method gave a peptide which resisted purification. Coupling proceeded readily by the mixed anhydride method but gave a tetrapeptide in which the valine residue had undergone 40% racemization. The tetrapeptide was eventually made without racemization by stepwise elongation.' Solid-state Methods.-This ingenious procedure in which the peptide chain is built up stepwise starting from an amino-acid linked via its carboxyl group to an appropriate solid support was introduced by Merrifield in 1962 and has undoubt- edly provided great impetus to peptide synthesis.The advantages of the method are (a) avoidance of problems of insolubility (b) speed and (c) convenience of operation and the feasibility of automation. The disadvantage is that the final product is not homogeneous since (i) coupling at each step can never be complete and by the very nature of the method purification of each intermediate is not possible and (ii) final cleavage of the product from the resin has traditionally required treatment with a strong acid (e.g. liquid hydrogen fluoride) and this can produce severe decomposition of the product.Much effort has been directed towards overcoming these difficulties (an authoritative review is available") but it remains true that purification of the final material (with the attendant difficulties of establish- ing homogeneity) is always necessary. A large number of papers in this field have recently been reported we can only summarize a few of these chosen to illustrate some points of general interest. The synthesis of prosomatostatin by an essentially conventional solid-state method has been reported." The peptide contains twenty-eight residues as shown in (5). It has been isolated from pig hypothalamus and intestine and is the putative precursor of somatostatin (residues 15-28) -a peptide of diverse biological activities including suppression of the release of insulin of glucagon and of growth 1 Ser-Ala-Asn 14 -Ser-Asn-Pro- Ala-Met- Ala-Pro- Arg-Glu-Arg-Lys-15 I 128 -Ala-Gly-Cys-Lys-Asn-Phe-Phe-Trp-Lys-Thr-Phe-Thr-Ser-Cys (5) J.W. van Nispen W. A. A. J. Bijl and H. M. Greven Recl. Trav. Chim. Pays-Bas 1980,99,57. lo G. Barany and R. B. Merrifield in ref. 1 p. 1. C. A. Meyers W. A. Murphy T. W. Redding D. H. Coy and A. V. Schally Roc. Natl. Acad. Sci. USA 1980,77,6171. Biological Chemistry -Part (iii) Peptides hormone. Synthesis was carried out by using the standard polystyrene/ 1% divinyl-benzene resin and amino-acids were coupled through their Boc-derivatives. Reac- tive side-chains were coupled as follows Cys 4-methylbenzyl; Thr and Ser benzyl; Glu 4-chlorobenzyl; Lys 2-chlorocarbobenzoxy ; Arg tosyl.Coupling was carried out by using di-isopropylcarbodi-imide,and was monitored at each step. The Boc protecting groups were removed by treatment with trifluoroacetic acid in methylene dichloride containing indole and the final product was cleaved from the resin and deprotected by using liquid hydrogen fluoride containing anisole. The crude sulphy- dry1 peptide was subjected to somewhat vigorous conditions in order to form the disulphide bridges and then purified by two successive gel-filtration steps followed by chromatography on CM-cellulose (carboxymethyl-cellulose).The major fraction from the last step was identified by using reverse-phase h.p.1.c. It was claimed that the final product was identical to the natural peptide using a variety of techniques (t.l.c.reverse-phase h.p.l.c. and amino-acid analysis) to assay the product. No evidence for the absence of racemization was given however. This work is interest- ing in that it appears to show that peptides of about thirty residues can be synthesized in a high state of purity by conventional solid-state procedures if appropriate strategies of protection coupling and deprotection are used. The synthesis of prosomatostatin using a fragment-condensation method has also been reported.'* The basic strategy was to protect the acid-labile side-chains (using t-butyl alcohol and adamanto13) and to use the S-t-butylthio-group for the protection of the two sulphydryl groups.The N* -2-nitrophenylsulphenyl group was used for chain elongation. Four suitably protected fragments corresponding to sequences 18-28 15-17 8-14 and 1-7 were assembled. The thio-groups were deprotected by reductive cleavage and other protecting groups were removed by trifluoroacetic acid. The disulphide bridge was formed by simple aerial oxidation. Final purification was achieved by gel filtration on Biogel P6 followed by ion- exchange chromatography on Biogel CM2. No direct estimation of the degree of racemization was given (except that afforded indirectly by tryptic digest) but the authors claimed that their final product was homogeneous as judged by t.1.c. and h.p.1.c. techniques. It would be interesting to know how this material (made under apparently mild conditions) compares with that made by the solid-state method.It has been realized for many years that improvements in solid-state synthesis could be made by changing the method of attachment of the first residue and by changing the nature of the resin itself. An example of the former is provided by a synthesis of thymosin al (6) reported by Wong and Merrifield.I3 This peptide contains twenty-eight residues and is a member of a family of peptides isolated from the thymus gland. Its biological function is unknown but it may be important in the development of the immune system. It has a number of unusual structural features. (a) It contains only ten of the twenty naturally occurring amino-acids all Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys- -Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala -Glu-Asn (6) E.Wunsch L. Moroder M. Gemeiner E. Jaeger A. Ribet L. Pradayrol. and N. Vaysse 2.Nuturforsch. Teil.B 1980.35,911. '' T. W. Wong and R. B. Merrifield Biochemistry 1980,19,3233. C. E. Dempsey and C. A. Vernon the aromatic and sulphur-containing amino-acids are missing. (b) It contains a high proportion of serine and threonine. (c) It is highly acidic. (d) The N-terminus is acetylated. Although synthesis of this peptide has previously been reported the method reported by Wong and Merrifield appears to be superior. The first amino- acid was attached to a 4-(oxymethyl)phenylacetamidomethylated resin rather than in the usual way via a benzyl-esterified resin.This gives enhanced acid stability and reduces the loss of peptide chains during synthesis. Protecting groups were conventional i.e. N“ -Boc-amino-acids were used throughout; trifunctional amino- acids were protected as Boc-Lys(TFA) Boc-Thr(Bzl) Boc-Ser(Bzl) Boc- Asp(OBzl) and Boc-Glu(OBzl) where Bzl is benzyl and OBzl is benzyloxy. Coupling (by DCC) was judged to be 99% after two cycles except at residues 14 17,and 22.Cleavage from the resin was achieved by liquid hydrofluoric acid and the protecting trifluoroacetyl groups were removed from the lysine residues by treatment with aqueous piperidine. Sequence analysis of the unpurified peptide- resin conjugate showed that ‘more than 80% of the chains synthesized were of the desired sequence’. This establishes the virtue of the described method of attachment to the resin.Purification of the deprotected peptide was achieved by the standard methods of gel filtration and ion-exchange chromatography and led to a product that was homogeneous by paper electrophoresis isoelectric focusing in polyacryl- amide gels and t.1.c. in a variety of solvent systems. Biological activity was found to be indistinguishable from that of the natural peptide. However as the authors are careful to point out this latter statement does not mean very much they say ‘while it is necessary to show that the products had biological activity it must be emphasized that the assay described is very imprecise’. This cautionary remark is laudable (and rare) and is particular appropriate to thymosin a1since the assay in vim (the ability of the peptide to reverse the inhibition by azathioprine of the formation of aggregates between mouse spleen cells and sheep erythrocytes) is certainly imprecise (the dose required varies by a factor of ten) and in any case cannot immediately be related to any putative physiological function.Sheppard has argued14 that some of the difficulties encountered in solid-state synthesis of peptides arise from the choice of the polymeric solid support and in particular that a polyamide support offers considerable advantages over the conventional polystyrene support essentially because it produces a polar environment that is more appropriate to the chemistry involved in peptide synthesis. He and his colleague^^^ have illustrated this by an elegant synthesis of human gastrin [hG17; residues 18-34 of sequence (3)].* The high content of glutamic acid and of tryptophan in this peptide makes it unsuitable for conventional solid-state synthesis since serious side-reactions occur under the strongly acidic conditions used.In the synthesis described the solid support that was used was a copolymer of dimethylacrylamide ethylenebis(acry1amide) (a cross-linking agent) and acryl- oylsarcosine methyl ester (containing the functional methoxycarbonyl groups). The functional groups were converted into primary amine groups by reaction with ethylenediamine. The first amino-acid residue was attached by using Boc-phenyl- * In fact in the synthesis reported Met-32 was replaced by Leu but this is of no consequence since the Leu-32 analogue is fully active and in any case the synthesis is applicable to the methionyl peptide.l4 R. C. Sheppard Biochem. SOC. Trans. 1980,8,774. Is E. Brown B. J. Williams and R. C. Sheppard J. Chem. SOC.,Chem. Commun. 1980,1093. Biological Chemistry -Part (iii)Peptides alanine anhydride in the presence of a catalyst. After cleavage of the Boc group the next sixteen residues were introduced by using the Fmoc-protected amino-acids. Symmetrical anhydrides were used for acylation except for the last residue (Gln) which was introduced as its p-nitrophenyl ester. Coupling proceeded in high yield at all steps and little (if any) loss of peptide from the resin occurred during the whole synthesis. After removal of protecting groups the peptide was detached from the resin (in 91% yield) by mild ammonolysis (saturated methanolic ammonia for 22 h).Final purification was by h.p.l.c. and led to a product that was homogeneous in a variety of procedures and that was biologically fully active. The authors concluded that the high efficiency of incorporation of amino-acids was due to the use of a polar solid support and that the relative freedom from side-reactions was due to the mild conditions used. Peptides from Genetic Manipulation.-Plasmids are circular DNA structures which exist in the bacterial cell independent of the single chromosome. It is relatively easy to isolate plasmids and to insert a DNA sequence that codes for a particular peptide into their structure.The modified plasmids can be put back into the bacterial cell and under favourable circumstances the new DNA sequence will be copied to give the corresponding peptide. In some cases the peptide will be ‘expressed’ (i.e. secreted) but in others it stays inside the cell. An example of the latter is the production of the A and B chains (21 and 30 residues respectively) of human insulin by (separate) cultures of E. coli. The two chains are isolated by breaking up the cells and then purified by conventional methods. They are joined together (uia the two disulphide bridges) by chemical means to yield human insulin. This process is apparently commercially viable and it may ultimately be cheaper to produce insulin in this way than by the extraction procedures from porcine or bovine pancreas that are currently used.16 An additional advantage is of course that human insulin would not produce the antigenic problems that sometimes arise from the use of procine or bovine insulin.This technique is in its infancy and much is to be expected of it over the next few years. One virtue is that if it is possible to persuade a bacterial cell to synthesize a particular peptide the syntheses will be accurate and the final product racemate- free. 2 Isolation of Naturally Occurring Peptides The purification of a peptide from a biological source is carried out by the (conven- tional) methods of gel filtration and ion-exchange chromatography backed up in the final stages by high-resolution techniques such as electrophoresis in a supporting gel and reverse-phase h.p.1.c.When (as is often the case) the peptide is a minor component of the original source material purification becomes a formidable undertaking. An example is provided by the isolation of somatomedin-C from human plasma.” This peptide of molecular weight about 7500 is a member of a family of peptides that appear to mediate somatic growth which is initiated by growth hormone. l6 J. Redfearn Nature (London) 1980,286,436. M. E. Svoboda J. J. Van Wyck D. G. Klapper R. E. Fellows F. E. Grissom and R. J. Schlueter Biochemistry 1980 19 790. C.E. Dempsey and C. A. Vernon Somatomedin-C is present only in very small amounts in plasma the purification procedure yielded 0.007 mg from 75 kg of plasma. The steps used were ion-exchange chromatography isoelectric focusing in polyacrylamide gel gel filtration and finally reverse-phase h.p.1.c.The final product was judged to be homogeneous by N-terminal analysis and by gel electrophoresis of the fluorescamine derivative but the authors make the cautious remark that it had an 'apparent purity of no less than 90"/0:. The problem of determining the purity of peptides is a severe one and particularly so if the peptide has been isolated from natural sources since contaminants may have biological activity of their own and this may vitiate pharmacological experi- ments. An example of the difficulty of attaining homogeneity by conventional methods is provided by recent studies on the peptide apamin. This peptide is highly basic contains eighteen amino-acid residues and occurs to the extent of about 2% (dry weight) in the venom of the common European Honey Bee (Apismellifera).It is the smallest known true neurotoxin and it also (at very low concentrations) blocks certain neurotransmitter-induced increases in potassium permeability. l8 Its biological effects make it of great interest to pharmacologists. Its structure is (7). Purification by conventional gel-filtration and ion-exchange chromatographic methods is known to be diffi~ult,'~ since the crude venom contains other basic peptides of about the same size. In particular it is difficult to remove melittin (8) which is the major component of bee venom and this is of some importance since melittin is a powei-ful lytic agent.Gly-Ile-Gly-Ala-Val-Leu-Lys-Val-Leu-Thr-Thr-Gly-Leu-Pro- -Ala-Leu-Ile-Ser-Trp-Ile-Lys-Arg-Lys-Arg-Gln-Gln-NH2 (8) It can be seen that the sequence of (8) contains a single tryptophan residue whereas that of (7)contains no aromatic residues. Consequently it has been found" that it is possible to determine the content of melittin in a given sample of apamin by monitoring the fluorescence emission of the tryptophan. It was shown by this method that a sample of apamin that had been subjected to repeated ion-exchange chromatography and that appeared to be homogeneous by t.1.c. nevertheless con- tained 2.5% of melittin (a commercial sample contained nearly 20%).It was further found that a single passage of a mixture of apamin and melittin through a column containing heparin that was linked to Sepharose beads gave an almost complete separation (the apamin sample contained ca 0.3% of melittin).The reason for the ease of this separation is by no means obvious but the method may be generally applicable to mixtures of basic peptides. B. E. C. Banks C. Brown G. M. Burgess G. Burnstock M. Claret T. M. Cocks and D. H. Jenkinson Nature (London),1979,282,415. l9 J. Gauldie J. M. Hanson F. D. Rumjanek R. A. Shipolini and C. A. Vernon Eur. J. Biochem 1976 61,369. *' B. E. C. Banks C. E. Dempsey F. L. Pearce C. A. Vernon and T. Wholley,Anal. Biochem.,in the press. Biological Chemistry -Part (iii) Pegtides 333 The use of reverse-phase h.p.1.c. is becoming standard practice in peptide chemistry although most workers use it as an analytical rather than a preparative technique.An attempt has been made” to predict retention times of peptides on the basis of their amino-acid composition. The results obtained by using twenty-five different peptides are impressive but a comparison of predicted values with those given in the literature” is (not surprisingly) less so. Although there is no doubt that reverse-phase h.p.1.c. is capable of very high resolution even with large pep- tides,23 the resolution with any particular peptide mixture may be highly dependent on the pH of the aqueous phase. Furthermore there are examples where resolution is not achieved under any of the conditions tried. A case in point is provided by some studies on human pancreatic polypeptide (HPP).24 This peptide has 35 amino-acid residues (the sequence is not given) and has a wide variety of effects on the gastrointestinal tract although its precise biological function is unknown.The peptide was synthesized by a conventional solid-state method and the final material was found to be indistinguishable from the native peptide on reverse-phase h.p.1.c. However it failed to be separated from the corresponding porcine peptide which is known to differ at two positions in the sequence (Asp for Asn at position 11and Glu for Asp at position 23) during h.p.1.c. The authors state that ‘the method is apparently not infallible’. An ingenious alternative to monitoring the purification of a peptide by biological or radioimmunoassay has been suggested for peptides in which the C-terminus is amidated” (as for example in the gastrin family where the C-terminus is always -Phe-NH2).The peptide mixture is treated with the enzyme thermolysin and the amidated C-terminal amino-acid that is thus released is detected as its fluorescent dansyl derivative using t.1.c. By this method two new peptides have been isolated from porcine intestine. Both peptides appear to belong to the secretin family. 3 Sequence Determination Amino-acid analysis is conventionally used to determine the stoicheiometric compo- sition of a peptide and (indirectly) the number of residues in the sequence. Precision falls rapidly with increase in chain length. A simple way of avoiding some of the difficulties has been described.26 In the example given sulphydryl groups (generated by reduction of disulphide bonds) were allowed to react with either iodoacetamide (which introduces no new charge) or iodoacetate (which introduces one negative charge per sulphydryl group) or with a mixture of the two reagents.Simple electrophoresis of the derivatives then enables the maximum number of new negative charges (and hence the number of sulphydryl groups) to be determined. The method is in principle applicable wherever a side-chain can be modified so that a change in charge occurs. Sequence analysis is still largely dependent on the Edman degradation procedure. Most workers use the automated version of this (i.e. the sequencer) and rely ” J. L. Meek Proc. Natl. Acad. Sci. USA 1980,77 1632.22 M. J. O’Hare and E.C. Nice I.Chromatogr. 1979,171,209. 23 D.H. Coy in ‘Biological/Biomedical Applications of Liquid Chromatography 11’ ed. G. L. Hawk Marcel Dekker New York 1979,p. 283. 24 C. A. Meyers and D. H. Coy Int. J. Peptide Protein Res.. 1980,16 248. ” K.Tatemoto and V. Mutt Nature (London) 1980,285,417. 26 T.E.Creighton Nature (London) 1980,284,487. 334 C. E. Dempsey and C.A. Vernon primarily on h.p.1.c. to identify the phenylthiohydantoin (PTH) derivatives. However it appears that the sequence of a peptide of about thirty residues is not usually determined completely by this method additional information must be sought. The difficulties are well illustrated by three recent papers on the sequence of prosomatostatin. It must be remembered that this peptide was known to be an N-terminally-extended derivative of somatostatin [residues 14-28; see structure (5)] the sequence of which had previously been determined.In the first paper,27 it is described how the peptide was isolated from porcine intestine and subjected to automated Edman degradation using 0.3 mg of starting material. Identification of the PTH derivatives was by h.p.l.c. but t.1.c. was also used. The authors say that ‘the repetitive yield [of derivative] was 96% initially but fell after cycle 15’. In the event the sequence was established only after analysis of the fragments obtained by treatment with cyanogen bromide (there is a single methionine residue at position 8) and by tryptic cleavage. In another paper2* the isolation of the peptide was described using ovine hypothalamus as the source.Automated Edman degrada- tion was carried out on approximately 0.01 mg but only a partial sequence was determined residues 4 17 24 26 27 and 28 were not identified. The authors synthesized the peptide corresponding to the sequence reported in ref. 27 and satisfied themselves that the synthetic peptide was identical to the one they had isolated. In a third paper2’ an even smaller amount of peptide (2 pg; isolated this time from porcine hypothalamus) was subjected to automated Edman degradation. The authors claim to have identified 26 of the 28 residues in this way; the two cysteine residues were however assigned by indirect evidence. Curiously enough the first four residues were assigned by the use of the dansyl-Edman procedure which was also carried out on 2 pg of peptide.It is perhaps somewhat surprising at first sight that most current papers on sequence studies report the use of the expensive sequencer-h.p.1.c. equipment when in principle manual methods (which cost very little) are capable of the same sensitivity. For example Hartle~,~’ writing in 1970 about the dansyl-Edman tech- nique said ‘the sensitivity of the method allows one to detect comfortably about 1nmol of DNS-amino acid’ (i.e.about 0.1 pg of amino-acid). This is by no means the limit of sensitivity of the method. The point is taken up in a paper31 that describes a manual ‘microsequencing procedure’ based on the Edman degradation. In this method the amino-acids are cleaved to give the thiazolinones which are not allowed to rearrange to the thiohydantoins but which are extracted and hydro- lysed to the amino-acids.The extraction method avoids many of the difficulties associated with the Edman method and the amino-acid analysis using the o-phthalaldehyde-fluorescence detection system leads to high sensitivity e.g. 1nmol or better for small peptides. It is of course also true that the use of what may be called standard sequencer equipment (i.e. equipment not especially designed for high sensitivity) can give disappointing results. In a of nerve-growth factor 27 L. Pradayrol H. Jornvall V. Mutt and A. Ribet FEBSLett. 1980 109 55. F. Esch P. Bohlen N. Ling R. Benoit. P. Brazeau and R. Guillemin Proc. Natl.Acad. Sci. USA 1980,77,6827. 29 A. V. Schally. W.-Y. Huang R. C. C. Chang A. Arimura T. W. Redding R. P. Millar M. W. Hunkapiller and L. E. Hood Proc. Nutl. Acad. Sci. USA 1980,77,4489. 30 B. S. Hartley Biochem. J. 1970 119 805. 31 H. S. Lu P. M. Yuan J. M. Talent and R. W. Gracy Anal. Biochem. 1981,110,159. 32 C. A. Chapman B. E. C. Banks C. A. Vernon and J. M. Walker Eur. J. Biochem. 1981 115 347. Biological Chemistry -Part (iii) Peptides (a small protein of about 120 residues) from guinea-pig prostate only the first fourteen residues could be unambiguously identified in a sequencer run and this required 1mg of material. Nevertheless considerable advances in methodology are being reported. A better solvent system for the identification of PTH derivatives of amino-acids by h.p.1.c.has been described,33 and it is stated that the system can be used routinely for sequencing of peptides and proteins in the 0.5-10 nmol range. Modifications in design and operation of existing equipment have led to a new sequencer (the Caltech sequenator) with a sensitivity that is at least ten times greater.34 Using this it was possible to determine all fourteen residues of somatostatin with 1.5 pg of material and the first thirteen residues of interferon (150 residues) from human fibroblasts on as little as 0.4 pg. An established alternative to the use of chemical methods to determine the sequence of peptides is mass spectrometry. The subject has been authoritatively surveyed by The method is capable of high sensitivity and also has the advantage that it is applicable to conjugated peptides (i.e.those that contain structures not derived from amino-acids) and to peptides that contain unusual amino-acids. The power of the method has been strikingly illustrated by the elucidation of the structures of some of the compounds belonging to the family known as slow-reacting substance (SRS).36 The name comes from the observation (some forty years ago) that antigen challenge to mast cells releases a substance that produces a slow but sustained contraction of smooth muscle which is not abolished by antagonists to histamine. Although it is now thought that other cells can also release SRS it is clear that at least one of these compounds (SRS-A slow-reacting substance of anaphylaxis) is released from the lung during anaphylactic shock.Conventional chemical methods did not lead to unambiguous structures partly because of the difficulty of purification and partly because of the very small amounts of material available. Purification was finally achieved by h.p.l.c. and the structure of SRS-A from guinea-pig lung was then determined by Morris and his colleagues by mass spectrometry using less than 1Opg of material. The structure that they determined is shown as (9).The mass spectrum was obtained by using the trimethyl- silyl ether of the N-acetyl methyl ester derivative. It can be seen that the molecule is an arachidonate derivative of a dipeptide and that it would be very difficult to determine its structure (given the small amount available) by means other than mass spectrometry.Chromatographic evidence suggests that the SRS-A of human lung has the same str~cture.~’ 33 F. Lottspeich Hoppe-Seyler’s 2.Physiol. Chem. 1980,361 1829. 34 M. W. Hunkapiller and L. E. Hood Science 1980 207 523. 35 H. R. Morris Nafure (London),1980 286 447. 36 H. R. Morris G. W. Taylor P. J. Piper and J. R. Tippins Nature (London),1980 285 104. 37 H. R. Morris P. J. Piper G. W. Taylor and J. R. Tippins Br. J. Pharmacol. 1979,67 179. 336 C. E. Dempsey and C. A. Vernon Most investigations of peptides using mass spectrometry that have so far been reported have involved the preparation of volatile derivatives. It is however possible to obtain a mass spectrum of an underivatized peptide by field desorption in which the peptide is directly applied to an appropriate emitter (usually silica).The method has been little used in the determination of the sequences of peptides because although it is not difficult to detect the molecular ion [w' or the quasi- molecular ion [M + HI' (thus giving the molecular weight) insufficient fragmenta- tion occurs to enable a sequence to be assigned. The problem has been neatly solved by determining the molecular weight by using field-desorption mass spec- trometry after successive cycles of the Edman degradati~n.~~ An example is provided by the field-desorption mass spectra of bradykinin (10)and its successively degraded fragments. Quasi-molecular ions were observed at m/z 1060 904 807 710 653 506 419 322 and 175 and this establishes the sequence of the peptide.The method cannot of course distinguish between leucine and isoleucine. Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe- Arg (10) Another method using underivitized peptides has been reported by Benyon and his c011eagues.~~ Negative-ion chemical ionization is used to generate an abundant [M -HI- ion. Separation of the peptides in the mixture is effected by mass selection using a reverse-geometry mass spectrometer. Fragmentation of the [M -HI- ion was effected by collision-induced dissociation using argon gas and mass-spec- trometric analysis of the fragments gives the necessary structural information. The method gave good results with a mixture of three tripeptides but its application to larger peptides has not yet been reported.4 Physical Studies A number of attempts have been made to determine the three-dimensional struc- tures of small peptides. The peptide apamin (7) which is available in relatively large quantity has been studied by 'H and 13Cn.m.r. spectroscopy (at 300 and 75 MHz respectively; in the Fourier-transform mode).40 The presence of two intra-chain disulphide bridges would be expected to confer considerable structural stability and this is confirmed by the fact that the c.d. spectrum does not change significantly over a wide range of pH and of solvent conditions and is unaffected by the presence of denaturing agents4' The n.m.r. study showed the presence of ten slowly exchangeable protons and these presumably are involved in hydrogen- bonding.In detail the structure proposed is that residues 6-13 are involved in an a-helix that two &turns (involving residues 2-5 and 12-15) occur about the disulphide bridges (residues 1-1 1 and 3-15) and that weaker hydrogen-bonds are formed by the backbone NH of Lys-4 with the hydroxyl group of Thr-8 by the backbone NH of Arg-14 with the carbonyl group of Gln-17 and by the backbone NH of Thr-8 with the side-chain carbonyl group of Asn-2 or the backbone carbonyl 38 Y. Shimonishi Y.-M. Hong T. Kitagishi T. Matsuo H. Matsuda and I. Katakuse Eur. J. Biochem. 1980,112,251. 39 C. V. Bradley I. Howe and J. H. Beynon J. Chem. Soc. Chern. Commun. 1980,562. 40 V. F. Bystrov V. V. Okhanov A. I. Miroshnikov and Yu. A. Ovchinnikov FEBSLett.1980,119 113. 41 A. I. Miroshnikov E. G. Elyakova A. B. Kudelin and L. B. Senyavina Bioorg. Khim. 1978 4 1022. Biological Chemistry -Part (iii) Peptides 337 group of Ala-5. It was further concluded that a salt bridge exists between the N-terminal amino-group and the carboxyl group of Glu-7 (although the estimated distance 0.5 nm is rather long) and that the only residue that is not involved in the three-dimensional structure is the C-terminal histidine amide. It must be emphasized that the conclusions reached in this study are permissive rather than compelling since the complete analysis of the n.m.r. spectrum of a peptide contain- ing eighteen residues is at the present time a formidable undertaking. Nonetheless the Russian workers are probably correct when they say that their structure ‘explains the spectroscopic results much better than the structures theoretically predicted’.4244 A similar study has been made of another peptide (peptide 401 or MCD peptide*) isolated from bee venom.45 The peptide contains twenty-two residues and has the structure (1 1).The structure has obvious similarities to that of apamin; there is a I Ile-Lys-Cys-Asn-Cys-Lys-Arg-His-Val-Ile-Lys-P~~-~~-Ile-~ys-Arg-Lys-Ile-Cys-Gly-Lys-Asn-NH preponderance of basic groups there are two disulphide bridges and the same number of residues in the smaller loop and there is amidation of the C-terminal residues and the common sequence -Cys-Asn-Cys-Lys-. The biological activities of the two peptides are however entirely different.As mentioned above apamin is a true neurotoxin whereas peptide 401 has powerful anti-inflammatory activity in a variety of animal models of inflammation and (paradoxically) is a potent agent for the release of histamine from mast cells (hence the alternative name of MCD peptide). The c.d. spectrum of this peptide like that of apamin shows little change over a wide range of solvent conditions. The authors give reasons for supposing that with small peptides containing disulphide bridges the prediction methods used for the structures of proteins are inapplicable. The ‘H n.m.r. spectrum was obtained at 360 MHz and showed the presence of six slowly exchanging protons. Many of the resonances were assigned but the most interesting feature of the spectrum was that the four signals due to the C-2 and C-5 protons of the imidazole rings of the two histidine residues all showed satellite peaks.The phenomenon was ascribed to conformational heterogeneity arising essentially from the presence of the sequence -Pro-His- at positions 12 and 13. Similar heterogeneity has been observed in angiotensin and related pep tide^.^^ High-resolution ‘H n.m.r. studies (at 360 MHz) of melittin (8) have been rep~rted.~’ It has been known for some years that the peptide forms a tetramer in solution but it has now been discovered that it reverts to a monomer at low pH and in the absence of salts. The n.m.r. spectra show that large conformational changes occur on aggregation. Twelve protons in each chain become slowly exchangeable and the best interpretation of the spectra is that interaction occurs between the essentially hydrophobic sections (residues 1-20) and that the highly * MCD = mast-cell-degranulating.42 P. N. Mel’nikov and E. M. Popov Bioorg. Khim. 1980 6,21. 43 B. Busetta FEBS Lett. 1980 112 138. 44 R.C.Hider and U. Ragnarsson FEBS Lett. 1980 111 189. 45 P.Walde H. Jackle P. L. Luisi C. E. Dempsey and B. E. C. Banks Biopolymers 1981,20,373. 46 M. Liakopoulou-Kyriakides and R. E. Galardy Biochemistry 1979,18 1952. 47 L. R. Brown J. Lautenvein and K. Wuthrich Biochim. Biophys. Acru 1980 622 231. 338 C. E. Dempsey and C.A. Vernon charged C-terminal sections are positioned at the maximum possible distance apart. Interestingly enough combination of the monomer with detergents or phospholipids to form micelles appears to involve similar conformational changes.Melittin has been crystallized in conventional manner from solutions of ammonium ~ulphate.~~ This finding is surprising since small peptides are notoriously resistant to crystallization. Two crystal forms and some isomorphous heavy-atom derivatives were obtained. Preliminary X-ray crystallography enabled an electron- density map to be constructed at 6 A resolution. It was concluded that the tetramer has 222 (D2) symmetry has the approximate dimensions 42 x 40 x 25 A and that the structure involves the maximum separation of the charged C-terminal segments (which is consistent with the n.m.r. spectra). ‘Complement’ is the name given to a family of proteins that form a cascade system and are involved in the defence mechanism against foreign material.In the inflammatory response the complement system is ‘activated’ and this involves inter alia limited and specific proteolysis of some of the components. The resulting fragments have profound biological activities which include causing an increase in vascular permeability and contraction of smooth muscle and have chemotactic effects on certain white cells. Two of these fragments known as C3a and CSa are called anaphylatoxins but this is a misnomer since it is now thought that anaphylac- tic shock is not mediated through c~mplement.~~ The C3a fragment is a peptide of 77 residues of known sequence. It has been reported” that the fragment is resistant to direct crystallization but that the peptide in which the C-terminal arginine residue has been removed by carboxypeptidase-B (to give de~-Arg~~-C3a) crystallizes readily.Furthermore seeding with crystals of this peptide induces crystallization of the native peptide and the two crystalline peptides are isomor- phous. An electron-density map at 3.2 8 resolution has been constructed and the peptide is said to ‘resemble a drumstick’ and to have the approximate dimensions 42 x 22 x 16A. Ordered structure starts at Tyr-15 and there are helical sequences and Gl~~~--Ser~’. T~r’~-Met~’ Cy~~~-Arg~~ The C-terminal sequence is essentially disordered. These results are interesting since it is known49 that the C-terminal hexapeptide retains some biological activity whereas removal of the C-terminal arginine residue results in complete loss of activity either in the native peptide or in any active fragment derived from it.These results present some difficulties for any current concept of structure-activity relationships. There have been attempts to group biologically active peptides into families the members of which show sequence homologies and functional relatedness. Blundell and Humbelsl have discussed this in terms of the pancreatic peptides which they have grouped into four families represented by insulin glucagon somatostatin and pancreatic polypeptide. They further suggest that the members of each family retain common features of three-dimensional structure. Although few crystal struc- tures of medium-sized peptides have been determined the data available (together with model building and the results of other physical measurements) seem to support this notion.48 D. Eisenberg T. C. Terwilliger and F. Tsui Biophys. J. 1980,32,252. 49 T. E. Hugli in ‘Contemporary Topics in Molecular Immunology’ Vol. 7 ed. R. A. Reisfeld and F. P. Inman Plenum New York 1978 181. R.Huber H.Scholze E. P. Plques and J. Deisenhofer Hoppe-Seyler’s2.Physiol. Chem. 1980,361 1389. 4.. L.Blundell and R. E. Humbel Nature (London) 1980,287,781. Biological Chemistry -Part (iii)Peptides 339 5 Endogenous Peptides The discovery that a variety of pharmacologically active peptides other than the classical peptide hormones occur in mammalian (and other) organisms has prompted a great deal of research aimed at finding the physiological roles of these substances.This is a complex and somewhat diffuse field and in this review we can quote only a few papers chosen to illustrate the problems involved. Vasoactive intestinal peptide (VIP) provides a good example. This peptide contains twenty-eight residues [see (12)]; it was first isolated from the gut and found to be a powerful vasodilator in a variety of pharmacological preparations. His-Ser-Asp-Ala-Val-Phe-Thr-Asp-Asn-Tyr-Thr-Arg-Leu-Arg-Lys- -Gln-Met- Ala-Val-Lys-Lys-Tyr-Leu-Asn-Ser-Ile-Leu-Asn-NH2 (12) The localization of a peptide by direct isolation from some particular cell type is usually extremely difficult and the procedure that is commonly adopted is to use immunohistochemistry or radioimmunoassay.This requires the production of an antibody and since most small peptides are weakly immunogenic this is accom- plished by conjugating the peptide as a hapten to a large protein such as bovine serum albumin. When this was done with VIP it was found that the peptide could be detected in a variety of cells of the gastrointestinal tract (including sphincter muscle and intramural neurones) and in the central nervous system. It has been known for many years that there is an inhibitory part of the autonomic nervous system in which the transmitter is neither acetylcholine nor adrenaline (the two ‘classical’ transmitters). Since VIP is apparently present in intramural neurones (nerve cells in the gut wall itself) the suggestion has been made that the peptide is the transmitter in the so-called third nervous ~ystem.’~-~~ A recent example is provided by some experimentsS5 on the lower oesophageal sphincter in which the inhibitory action of nerve stimulation can be mimicked by the application of VIP and both effects can be partially abolished by antiserum to VIP.The authors concluded that the ‘findings provide evidence of a role for VIP as an inhibitory transmitter’. This view of the role of VIP has been firmly resisted by Burnstock and his colleagues. In a paper56 reporting experiments on taenia coli (a piece of longitudinal muscle which can easily be dissected out together with the accompanying nerve plexus from guinea-pig caecum) they show that the relaxation produced by VIP has a longer latency than that produced by nerve stimulation or by application of ATP and unlike the latter it is abolished by chymotrypsin.Furthermore apamin which blocks the effect of nerve stimulation or application of ATP has no effect on the response produced by VIP (see also ref. 18).It is concluded that the inhibitory transmitter is a purine nucleotide probably ATP. It seems difficult not to accept the view of Burnstock and his colleagues about this system. 52 J. Fahrenkrug U. Haglund M. Jodal 0. Lundgren L. Olbe and 0. B. Schaffalitzky de Muckadell J. Physiol. (London),1978 284 291. 53 K. G. Morgan P. F. Schmalz and J. H. Szurszewski J. Physiol. (London),1978,282,437. 54 J. B.Furness and M. Costa Neurosci. 1980,5 1. 55 R.K. Goyal S. Rattan and S. I. Said Nature (London),1980,288 378. I. Mackenzie and G. Burnstock Eur. J. Pharmacol. 1980,67 255. C.E. Dempsey and C.A. Vernon Other peptides have also been implicated as neurotransmitters. Evidence support- ing the view that substance P is a neurotransmitter in the myenteric plexus (guinea- pig small intestine) has been presented.” Substance P was originally isolated from the gut and is a peptide of twelve residues contains the sequence -Phe-Phe- and has the C-terminal residue amidated. Consequently the peptide should be degraded by chymotrypsin but unaffected by carboxypeptidase-A. Consistently it was found that transmission in the particular preparation used was reversibly depressed by chymotrypsin but not by carboxypeptidase-A.Another claim for peptidergic trans- mission comes from experiments on frog sympathetic ganglia (paravertebral gang- lia).s8 Intracellular recording of potential shows that four different types of potential changes can be induced in this preparation three are due to acetylcholine and the fourth (slow) change is due to an unknown transmitter. It was shown that the slow potential change can be mimicked by Luteinizing-Hormone-ReleasingFactor (LHRF). This peptide contains ten residues and its established function is to promote the release of luteinizing hormone from the pituitary. The reason why the authors supposed that it might be the unknown transmitter was that radio- immunoassay showed that a compound of similar immunological reactivity occurs in the presynaptic axons of the sympathetic ganglia of the frog.There is at the moment no compelling evidence to suppose that any peptide functions as a transmitter in the classical sense. It does however appear that many neurones contain both a classical transmitter and a peptide.” For example the adrenal medulla contains noradrenaline and somatostatin whereas autonomic ganglia that innervate certain exocrine glands contain acetylcholine and VIP. It has been suggested that the transmitter and the peptide may act synergistically; for example in exocrine glands acetylcholine is responsible for the secretion (which is blocked by atropine) whereas VIP may induce vasodilation (not blocked by atropine). Alternatively the peptide may directly modify the effect of the transmitter.Evidence for this view comes from the observation that substance P may block cholinergic receptors.60 It must be remembered that in many cases where peptides have been identified in central nervous tissue immunological procedures have been used. These have the advantage of sensitivity and convenience but are not without their dangers. The antibody may react with structurally related antigens and if the antigenic determinant (which may be a sequence of not more than four or five amino-acids) happens to be the same with structurally unrelated antigens. Hence careful workers refer to substance-P-like immunoreactivity and not to substance P.61 Another problem is illustrated by a paper on mast cells.62 The authors detected the presence of a substance that reacts with an antibody to the mid-region of ACTH by immunohistochemistry.They then examined cell extracts by a radioimmunoassay procedure. This involved measuring the ability of the extract to displace radio- labelled ACTH from specific antibody. A large amount of activity was found. ” K. Morita R. A. North and Y. Katayama Nature (London) 1980,287,151. Y. N. Jan L. Y. Jan and S. W. Kuffler Proc. Narl. Acad. Sci. USA 1980 77 5008. ’’ T,Hokfelt 0.Johansson A.Ljungdahl,J. M. Lundberg,andM. Schultzberg Nature (London) 1980,284 515. 6o F. Mizobe V. Kozousek D. M. Deanne and B. G. Livett Brain Res. 1979,178,555. T. Hokfelt J. M. Lundberg M. Schultzberg 0. Johansson L. Skirboll A. Angglrd B. Fredholm B. Hamberger B.Pernow J. Rehfeld and M. Goldstein Proc. R. Soc. London Ser. B. 1980,210,63. R. P. Di Augustine L. H. Lazarus G. Jahnke M. N. Khan M. D. Erisman and R. I. Linnoila Life Sci. 1980 27 2663. Biological Chemistry -Part (iii) Peptides 341 However activity was lost on treatment with 0.1M acetic acid and on boiling (ACTH should resist both treatments) and furthermore the activity appeared on gel filtration to be associated with a protein of molecular weight greater than 50 000. The authors concluded that the results obtained by radioimmunoassay were artefactual and arose from the presence of a protease that cleaved antigen and hence released radiolabel from the antibody. The origin of the immunohistochemical localization remains obscure.It is of course widely appreciated that all immunological techniques depend on the use of pure antigen.61 If the antigen used to raise antibody contains an immunogenically active contaminant then spurious results are likely. What is not so often appreciated is that direct biological assay may also be vitiated by the presence of contaminants. A recent example is provided by some experiments described by Fitzsimons and his c011eagues.~~ These workers found that intracerebral injection of nerve-growth factor (NGF) preparations into rats produced a profound dipsogenic (thirst-promoting) effect. In fact the animals would drink sodium chloride solutions to which they would normally be totally averse. It was however noticed that the effects were similar to those produced by angiotensin-I1 (13).This peptide Asp-Arg-Val-Tyr-Val- His-Pro-Phe (13) is a powerful pressor substance and its production is initiated by the enzyme renin in response to a fall in the arterial supply to the kidney.It is probably also involved in the central control of thirst. Fitzsimons and his c011eagues~~ found that pure NGP5 has no dipsogenic activity and they concluded that the effects originally observed were due to a contaminant. Almost certainly the contaminant was renin since this enzyme occurs in large amount in the source from which NGF is normally prepared (mouse submandibular gland). The above comments are not of course to be taken as meaning that localization of peptides by immunological techniques is invalid.There is at the moment no other way of determining whether a given peptide occurs in a particular cell type. In some cases immunological detection has been followed by complete isolation and characterization e.g. substance P and neurotensin have been isolated from both gut and brain.66 Further it has been found that ‘authentic’ VIP occurs in brain extracts from all species so far e~amined.~’ Immunological techniques are indispen- sable in this field of research but the results obtained from them taken in isolation must always be viewed with caution. There has been renewed interest in two peptide hormones which have been known for a long time i.e. vasopressin (14)and oxytocin (15).In some species I I Cys-Tyr-Phe-Gln- Asn-Cys-Pro- Arg-Gly-NHz (14) r 1 Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2 (15) M.E. Lewis D. B. Avrith and J. T. Fitzsimons Nature (London) 1979,279,440. 64 D. B. Avrith M. E. Lewis and J. T. Fitzsimons Nature (London) 1980 285,248. ‘’ C. A. Chapman B. E. C. Banks J. R. Carstairs F. L. Pearce and C. A. Vernon FEBS Lett. 1979 105 314. 66 G. J. Dockray and R. A. Gregory Proc. R. SOC. London Ser. B 1980,210 151. ‘’ R. Dimaline and G. J. Dockray Life Sci.,1979,25 1893. 342 C.E. Dempsey and C.A. Vernon Arg-8 of vasopressin is replaced by lysine. The structural similarities between (14) and (15) are obvious the established physiological roles of the two peptides are however entirely different. Oxytocin is involved in parturition and lactation whereas vasopressin controls the re-adsorption of water in the kidney.Both peptides are synthesized in the hypothalamus and transported (via the hypothalamic tract) to the posterior pituitary. In diabetes insipidus there is a failure to secrete vasopressin and patients with this disease produce a large volume of dilute urine per day (up to 20 litres). Clinical observation has shown that the disease is also associated with cognitive problems and this suggests that the peptide also has some central function. Vasopressin has been localized in the limbic system of the brain; since this system is known to be involved in memory processes the question arose as to whether vasopressin is in any way involved in memory. The earlier experiments were done by de Wied,68 who used rats which had been taught to run mazes and then rendered partially amnesic by injection of puromycin.It was found that vasopressin reversed the effects of puromycin whereas oxytocin had the opposite effect. Experiments in humans appear to give results consistent with these observa- tions. In a double-blind trial involving volunteers 1-desamino-[8-~-arginine]-vasopressin or a placebo was administered intranasally (30-60 pg) three times a day over a period of two weeks.69 The results showed that the subjects treated with the vasopressin analogue showed an enhancement of learning ability and of short-term memory recall. It was also claimed that the vasopressin analogue partially reversed the amnesia following electroconvulsive therapy and alleviated the cognitive impairments present in senile dementia (Alzheimer's syndrome).In another intravenous injection of oxytocin into volunteers was found not to affect learning or immediate memory recall but to impair later memory recall. It was concluded that oxytocin in addition to its established physiological functions (in the female) may be a natural amnesic agent. All these results were obtained when using relatively high doses of peptides but since their ability to penetrate the blood-brain barrier has not been determined the amounts reaching the limbic system (the presumed target area) remain unknown. Research on enkephalins continues to attract considerable attention. The two pentapeptides methionine-enkephalin (16) and leucine-enkephalin (17)" were first isolated and characterized from brain tissue by Hughes and his colleagues in 1975.'l Tyr-Gly-Gly-Phe-Met Tyr-Gly-Gly-Phe-Leu (16) (17) * These names can cause confusion in that they are sometimes abbreviated e.g.to Met-enkephalin or mistaken for methionyl-enkephalin both of which represent enkephalin that is extended at the N-terminus by the addition of a methionyl residue. Such problems might have been avoided if the name enkephalin had been given to the tetrapeptide Tyr-Gly-Gly-Phe which is then C-terminally extended by -Met (i.e. enkephalin-Met or enkephalin-methionyl) or -Leu but the names methionine-enkephalin and leucine- enkephalin have been widely adopted for peptides (16) and (17). D. de Wied Proc. R. SOC.London Ser. B 1980 210 183. 69 H.Weingartner P.Gold J. C. Ballenger S. A. Smallberg R. Summers D. R. Rubinow R. M. Post and F. K. Goodwin Science 1981 211 601. 'O B. M. Ferrier D. J. Kennett and M. C. Devlin Life Sci. 1980,27,2311. '' J. Hughes T. W. Smith H. W. Kosterlitz L. A. Fothergill B. A. Morgan and H. R. Morris Nature (London) 1975,258,577. Biological Chemistry -Part (iii)Peptides 343 Because the peptides are present in very small amounts this work represented a very considerable achievement. The peptides were found to have effects on guinea- pig ileum that were similar to those produced by morphine i.e. the contraction of the muscle wall following electrical stimulation of the myenteric plexus is prevented. The effects are blocked by naloxone-a known antagonist to morphine.The peptides will bind to membrane fractions obtained from central-nervous tissue but several different types of receptor appear to be present. The localization of enkephalins by radioimmunoassay has indicated that they occur (usually together with a classical transmitter) in a variety of structures of the central nervous system but the distribution has not shed much light on their physiological role. The lifetime of the enkephalins in the central nervous system is extremely short (probably due to degradation by enzymes which have not yet been completely characterized) and this has given rise to the suggestion that they function as transmitters. It has been shown that the peptides have an inhibitory effect on some central neurone~~**~~ but an excitatory effect on others.However careful electrophysiological experiment~~~ have shown that the latter effect arises from a depression of activity of inhibitory interneurones. It has been pointed out by Wall and Woolf7’ that speculation about the role of enkephalins in pain should be treated with reserve they particularly attack the suggestion that amelioration of pain due to the release of enkephalins is involved in acupuncture. Many analogues of enkephalins have been synthesized and tested for opiate activity. It appears that residues at positions 1and 4are of importance76 although as usual with structure-activity studies no very clear-cut conclusions have emerged. The analogue (18) has been reported to be extremely effective at the so-called D-Tyr-Ser-Gly-Phe-Leu-Thr (18) 8-receptor (possibly involved in behaviour and much less so at the preceptor (possibly involved in analge~ia~~).Effects in viuo have however not yet been reported. The sequence of methionine-enkephalin is contained in y-endorphin (4) which is a member of another (and apparently distinct) family of opiate peptides. The obvious suggestion is that the pentapeptide is a cleavage product of y-endorphin (or if its percursor). However this appears not to be the case since first cleavage would have to occur at a hitherto unknown cleavage point (between -Met- and -Thr-) and secondly enkephalins are found in some cells that do not contain endorphins and vice versa.79Moreover leucine-enkephalin cannot arise in this way since its sequence is not contained in the endorphins or in their precursors.72 S. H. Snyder Harvey Lect. 1979 79 291. 73 R. A. North LifeSci. 1979 24 1527. 74 R. A. Nicoll B. E. Alger and C. E. Jahr Nature (London) 1980,287,22. 75 P. D. Wall and C. J. Woolf Nature (London) 1980 287 185. 76 F. A. Gorin T. M. Balasubramanian T. J. Cicero J. Schwietzer and G. R. Marshall J. Med. Chem. 1980,23,1113. 77 H. Rigter T. J. Hannan R. B. Messing J. L. Martinez B. J. Vasquez R. A. Jensen J. Veliquette and J. L. Mcgaugh Life Sci. 1980 26,337. 78 H. W. Kosterlitz J. A. H. Lord S. J. Paterson and A. A. Waterfield Br. J. Pharmacol. 1980,68 333. 79 M. J. Brownstein Nature (London),1980 287 678. 344 C. E. Dempsey and C A. Vernon The search for the precursors of the enkephalins has led to the isolation of a bewildering variety of peptides that contain the required sequences.The peptides whose sequences are shown as (19) (20) and (21) have been isolated from porcine hypothalamus,80 tumour of the human adrenal medulla (and bovine adrenal medulla),81 and porcine pituitary,82 respectively. The peptide whose sequence is given in (21) has become known as dynorphin. Tyr-Gly-Gly-Phe-Met-ArgTyr-Gly-Gly-Phe-Met-Arg-Phe (19) (20) Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-Arg-Pro-Lys-Leu-Lys (21) Much larger putative precursors have been found in bovine adrenal medulla. A protein of molecular weight approximately 50 000 was found to yield methionine- enkephalin and leucine-enkephalin in the ratio 7 :1when digested with trypsin and carboxypeptidase-B.The enkephalins were identified by chromatography and by their binding to opiate receptors and it was concluded that the original protein contains seven copies of methionine-enkephalin and one copy of leucine-enkephah8’ It is apparently also possible to find a variety of peptides in the adrenal medulla with molecular weights ranging from 500 to 25 000 that either bind directly to opiate receptors or do so after treatment with tryp~in.~~ One pep- tide (peptide F) was subjected to sequence analysis and found to contain thirty- four residues.85 It has the methionine-enkephalin sequence twice one being at the N-terminus (where the sequence is followed by -Lys-Lys-) and the other at the C-terminus (where the sequence is preceded by -Lys-Arg-).Cleavage of many precursors (e.g. proinsulin proglucagon and proalbumin) is known to take place at points where a pair of basic amino-acids occur so it seems likely that the peptide could give rise to two molecules of methionine-enkephalin. The significance of the occurrence of multiple enkephalin sequences in larger peptides and proteins is not understood and this is equally true of the significance of the wide diversity of peptides containing the sequences. 6 Exogenous Peptides It has been known for many years that the skins of amphibians are rich storehouses of pharmacologically active peptides. The subject has been reviewed by Erspamer (one of the pioneers in this field) and Melchiorri.86 One of the most interesting 80 W. Y.Huang R. C. C. Chang A. J. Kastin D. H. Coy and A. V. Schally Proc. Natf. Acad. Sci. USA 1979,76,6177. 81 A. S. Stern R. V. Lewis S. Kimura J. Rossier L. D. Gerber L. Brink S. Stein and S. Udenfriend Proc. Natl. Acad. Sci. USA 1979,76 6680. 82 A. Goldstein S. Tachibana L. I. Lowny M. W. Hunkapiller and L. Hood Proc. Natl. Acad. Sci. USA 1979,76,6666. 83 R. V. Lewis A. S. Stern S. Kimura J. Rossier S. Stein and S. Udenfriend Science 1980 208 1459. 84 S. Kimura R. V. Lewis A. S. Stern J. Rossier S. Stein and S. Udenfriend Proc. Natl. Acad. Sci. USA 1980,77,1681. 85 B. N. Jones A. S. Stern R. V. Lewis S. Kimura S. Stein S. Udenfriend and J. E. Shively Arch. Biochem. Biophys. 1980 204 392. 86 V. Erspamer and P. Melchiorri Trends Pharmacol. Sci. 1980 1 391.Biological Chemistry -Part (iii) Peptides peptides isolated is bombesin which has powerful pharmacological effects on the gastrointestinal tracts of mammals it is a potent releaser of gastrin and a stimulant of the gastric secretion of acid it releases cholecystokinin (in the dog) is a direct stimulant of gall-bladder musculature acts on the pancreas and (in the rat) has profound effects on the central nervous system. Its sequence is given in (22). Bombesin-like immunoreactivity has been detected in mammals but the significance of this is doubtful. Recently however a peptide that resembles bombesin has been isolated from porcine non-antral gastric tissue and shown to have the sequence shown in (23). The common residues are italicised and it can be seen that the ~lu-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2 (22) Ala-Pro-Val-Ser-Val-Gly-Gly-Gly-Thr-Val-Leu-Ala-Lys-Met --Tyr-Pro-Trp-Ala- Val-Gly -His-Leu-Met-NH2 Arg-Gly -Am -His-(23) C-terminal decapeptide sequence (apart from one substitution) is the same in both peptides.This is interesting since it is known that the C-terminal nonapeptide from bombesin possesses the full range of activities of the parent molecule. Whether or not the bombesin-like peptide isolated from gastric tissue is a true hormone remains to be established. Another interesting peptide that has recently been isolated from frog skin (of the species Phyllomedusa sauvagei) has been called dermorphin.86 The peptide contains seven residues and has the seQuence shown in (24).Apart from the Tyr-D-Ala-Phe-Gl y -Tyr-Pro-Ser-NH2 (24) N-terminal tyrosine residue the peptide has no obvious structural similarities to the enkephalins. Nevertheless it is reported to have profound opiate-like effects on the peripheral and central nervous systems. On a molar basis it is 35-100 times more active than methionine-enkephalin in the guinea-pig ileum preparation and 3040 times more active than morphine. On intracerebroventricular injection into rats its analgesic effect is 1000 times greater than that of morphine. Unlike the enkephalins the peptide is resistant to proteolysis its effects in uivo are therefore long-lasting. The most astonishing thing about the peptide is that the alanine in position 2 is in the D configuration.Furthermore this residue is essential for activity synthetic material containing L-alanine is said to have less than 0.1% of the activity of the natural or of synthetic dermorphin. This appears to be the first peptide to be isolated from a vertebrate which contains an amino-acid in the D configuration. Presumably its biosynthesis cannot involve the normal genetic coding mechanism. The venoms of elapid and hydrophid snakes are rich sources of peptides contain- ing between 60 (short) and 70 or more (long) residues. Many of these are highly toxic and they act postsynaptically. The venoms also contain structurally related peptides which have much reduced toxicity or none at all. On the basis of the sequences now known an attempt has been made to determine those features that C.E. Dempsey and C. A. Vernon are necessary for A new peptide has been isolated from the venom of Dendroasgis jamesoni kaimosae (Jameson’s mamba) and found to be a short neurotoxin but with rather low toxicity.88 Sequence analysis showed that it con- tained structural features similar to those found in the highly toxic shor neurotoxins. The ten structurally invariant amino-acids (necessary for correct folding) are con- served but only one of the three amino-acids that are considered to be necessary for activity is present. The precursor of melittin continues to attract attention. Promelittin contains the sequence (25) tacked on to the N-terminus of melittin (8).This extraordinary sequence (25) is highly acidic and it would be expected to modify both the folding Ala-Pro-Glu-Pro-Glu-Pro-Ala-Pro-Glu-Pro-Glu-Ala-Glu- -Ala-Asp- Ala-Glu- Ala-Asp-Pro-Glu- Ala-melittin (25) and the biological activity of the melittin fragment.Furthermore the point of cleavage is not associated with a pair of basic amino-acids (see Section 5 the discussion of the enkephalins). It has been found that an enzyme dipeptidyl peptidase IV that can be isolated from kidney will degrade promelittin by success- ively splitting off dipeptides from the N-terminu~.~~ Degradation stops when the N-terminus of the melittin fragment (i.e. Gly-) is reached. It has been suggested that this represents a new type of precursor-product conversion. Since the enzyme involved came from a mammalian source it is possible that other examples of this process will be found.87 E. Karlsson in ‘Handbook of Experimental Pharmacology’ ed. C.-Y. Lee Springer Verlag Berlin 1979 Vol. 52 p. 159. F. J. Joubert and N. Taljaard Znt. J. Biochem. 1980,12,567. 89 G. Kreil L. Haiml and G. Suchanek Eur. J. Biochem. 1980 111 49.

ISSN:0069-3030    

DOI:10.1039/OC9807700323

出版商:RSC    

年代:1980

数据来源: RSC

摘要:

15 Biological Chemistry Part (iv) Enzyme Chemistry By C. A. ROSS Department of Biochemistry University College Cork Lee Makings Prospect Row Cork Ireland 1 Introduction The main event to occur in the publishing field in this area of interest during the past year must be the appearance of the third edition of the now classical text ‘Enzymes’ by Dixon and Webb.’ Some twenty-two years have elapsed since the first appearance of this book and eighteen since the second edition so obviously an overhaul was long overdue. Two new authors have been added Thorne and Tipton both from the Cambridge school so that the unique character of the book remains. This includes a classified list of known enzymes with references which takes up a quarter of the book and one must question the value of such a list especially as the I.U.B.3‘Enzyme Nomenclature’ ’also arrived on the bookshelves during the year.Over 2000 enzymes are now classified but the latest edition of this essential reference work unfortunately omits the useful chapter on Symbols of Kinetic Analysis. The I.U.B. was also responsible for another notable event in 1980 the appearance of a new monthly journal Biochemistry International which commenced in July. The new journal is aimed at the rapid (6-8 weeks) publication of papers in the whole field of biochemistry and the manuscript supplied is reproduced directly. It is claimed that the editors will ensure the scientific merit and originality of material selected for publication. At the other end of the scale in 1980 the Journal of Biological Chemistry achieved its 75th anniversary and still does not require its contributors to give in their reports the EC reference numbers for enzymes.Reports from the 1.U.B Meeting in Toronto in July 1979 are now becoming available. The Ayerst Award Lecture given by James on the X-ray crystallographic approach to enzyme structure and function has now been p~blished,~ as have Gutfreund’s views on future problems in en~ymology.~ Fluorescent probes of active sites of proteinases have been reviewed by Fruton’ and of the flavoproteins by ‘ M. Dixon E. C. Webb C. J. R. Thorne and K. F. Tipton ‘Enzymes’ Longman Group Ltd. London 3rd edn. 1979 [Reviewed by E. M. Crook,Biochem. SOC.Trans. 1980,8,401]. * ‘Enzyme Nomenclature’ Recommendations (1978) of the Nomenclature Committee of the International Union of Biochemistry Academic Press London 1979 [Reviewed by P.Bohley FEBS Lett. 1980 116 1361. M. N. G. James Can. J. Biochem. 1980,58,251. H. Gutfreund Can. J. Biochem. 1980,58 1. ’ J. S. Fruton Mol. Cell. Biochem. 1980,32 105. 347 348 C. A. Ross Massey and Hemmerich.6 Among the structures reported during the year was the crystal structure of cytochrome c peroxidase7 and the primary structures of triosephosphate isomerase8 and of glyceraldehyde 3-phosphate dehydrogenase.' Two reviews and a number of books" have appeared on the topic of immobilized enzymes and there is an interesting paper on the immobilization of NADH in a soluble and enzymically active form.'' Intriguing reports were noted on the bio- chronological applications of amino-acid racemization l2 on sarcosine oxidase which is claimed to be a unique enzyme with both covalently and non-covalently bound flavins,13 and on the preparation of a cytidine-specific RNase from chicken 1i~er.I~ Finally mention must be made of a review of Lowry's method for protein estimation which is widely used in enzyme preparative work." 2 Calmodulin Brief mention of calmodulin was made in last year's Report and since then several important reviews have appeared.16 Recognition of the importance of calmodulin in regulating the metabolism and motility of living cells has now reached such a point that it is almost more pertinent to enquire which cellular mechanisms are not dependent upon calmodulin than to enumerate those which are.Calmodulin exists as a monomer of 148 amino-acids of molecular weight 17 000 with remarkable stability in the presence of Ca2'. The complete sequence of the protein from bovine brain has been publi~hed'~ (see Figure l) and the evidence to date is that the structure has been highly conserved throughout the plant and animal kingdoms. While many similarities exist between calmodulin and other Ca2'-binding proteins such as troponin-C it has as a distinctive feature a post-transcriptionally trimethy- lated E-amino-group of lysine-115 and is also some seven to eight amino-acid residues shorter at the amino-terminal region. Because of the high degrees of homology displayed at the Ca2'-binding sites (especially between sites I and I11 and between I1 and IV in calmodulin) it would seem that the Ca2'-binding proteins arose by gene duplication from a smaller ancestral precursor which bound a single Ca2+ ion.V. Massey and P. Hemmerich Biochem. SOC.Trans. 1980,8 246. T. L. Poulos S. T. Freer R. A. Alden S. L. Edwards U. Skogland K. Takio B. Eriksson N-H. Xuong T. Yonetani and J. Kraut J. Biol. Chem. 1980 255 575. * S. Artavarris-Tskonas and J. I. Harris Eur. J. Biochem. 1980 108 599. J. D. Hocking and J. I. Harris Eur. J. Biochem. 1980,108 567. lo (a)G. G. Bickerstaff Int. J. Biochem. 1980 11 201; (b)T. T. Ngo ibid. p. 459; (c) 'Enzymic and Non-Enzymic Catalysis' ed. P. Dunnill A. Wiseman and N. Blakebrough Ellis Horwood Chichester 1979; (d)'Enzyme Technology Applied Biochemistry and Bioengineering' Vol.2 ed. L. B. Wingard E. Katehalski-Katzir and L. Goodstein Academic Press New York 1979; (e)'Enzyme Engineering Future Directions' ed. L. B. Wingard I. V. Berezin and A. A. Klyasov Plenum Press New York 1980; (f)M. D. Trevan 'Immobilized Enzymes' John Wiley & Sons Chichester 1980. l1 C. W. Fuller J. R. Rubin and H. J. Bright Eur. J. Biochem. 1980,103,421. '* J. L. Bada and S. E. Brown Trends Biochem. Sci. 1980 5 Sept. p. 111. l3 S. Hayashi S. Nakamura and M. Suzuki Biochem. Biophys. Res. Commun. 1980,96 924. l4 (a)C. C. Levy and T. P. Karpetsky J. Biol. Chem. 1980,255 2153; (6) M. S. Boguski P. A. Hieter and C. C. Levy ibid.,p. 2160. l5 G. L. Peterson Anal. Biochem. 1979 100 201.l6 (a)A. R. Means and J. R. Dedman Nature 1980 285 73; (6) C. B. Klee T. H. Crouch and P. G. Richman Annu. Rev. Biochem. 1980 49 489; (c) J. H. Wang and D. M. Waisman Curr. Top. Cell. Regul. 1979,15,47;(d)W. Y. Cheung Science 1980,207,19. D. M. Watterson F. Sharief and T. C. Vanaman J. Biol. Chem. 1980 255 962. Biological Chemistry -Part (iu) Enzyme Chemistry Figure 1 The sequence of bovine brain calmodulin showing the four proposed Ca2+-binding domains with the stretches ofa-helix in darker circles (Reproduced by permission from Annu. Rev. Biochem. 1980,49,489) The tertiary structure of calmodulin is markedly altered in the presence of Ca2' the CY -helical content that is detected by far-u.v. circular dichroism being variously reported as increasing by 5-10%.Conflicting observations on the affinities of the four Ca2+-binding sites and on the co-operativity that exists between them have been published. In a recent paper,'* Crouch and Klee have determined the dissocia- tion constants for the four sites as being between 3 x lop6and 2 x lo-' moll-' and have observed positive co-operativity with Hill coefficients of 1.33 and 1.22 in the absence and in the presence of 3mM-Mg2+ respectively. The binding of metal ion appears to be by a sequential mechanism generating at least four different conformers of the protein (CaM) in its free and liganded state CaM + nCa2+ $ CaM.Ca2+ $ CaM*-Ca2+ (1) Subsequently the active conformer of calmodulin (indicated by an asterisk) interacts with an enzyme which may be inactive or only partially active CaM*.Ca2+ + E $ (CaM*.Ca2+,).E $ (CaM*Ca2+,).E* (2) The stoicheiometry of both equations can clearly vary so giving rise to a number of possible combinations.These will have to be determined for each calmodulin- dependent protein which may itself be capable of binding Ca2' directly. In con- sequence the calmodulin activation system has the capacity to exist in multiple T.H. Crouch and C. B. Klee Biochemistry 1980,19.3692. 350 C. A. Ross forms for the differential regulation of a large number of cellular mechanisms. Thus cyclic nucleotide phosphodiesterase appears to require the calmodulin Ca2+34 complex which it binds with a Kd =1-3 x mol 1-'.l8 On the other hand phosphorylase kinase has the structure where the y-subunit is identical with calmodulin and which can in the presence of calcium ions interact with a further molecule of calmodulin (termed the $-subunit) or with troponin-C of skeletal muscle so that the enzymic activity is increased." This enzyme which exists in a high-activity phosphorylated form (phosphorylase a) and a low-activity dephosphorylated form (phosphorylase b) has varying affinities for calmodulin troponin-C and Ca2'.The interconversion of.forms a and b is under hormonal control and so a most elaborate control system exists linking the regulation by cyclic nucleotides and by Ca2' mediated by at least two Ca*'-binding proteins. In general terms this can be depicted as in Scheme 1. hormonal nervous stimulation stimulation + intracellular Ca" extracellular Ca2+ aden ylate phosphodiesterase I cyclase .\ I \ \ \ . \ \ \ 7... .\ kina< -.\ -21E.CaM.Ca2' dephosphoprotein phosphoprotein / bioc6emical response (E.CaM.Ca2+ may stand for those enzymes indicated by the dashed lines or others listed in refs 16a and 164 Scheme 1 To the lists of calmodulin-mediated processes in refs. 16a and 16d can now be added DNA synthesis,20 which can be initiated in rat liver cells in a low-calcium medium (0.02 mmol 1-') by raising the concentration of metal ion to 1.25 mmol 1-'. The initiation could be blocked by the putative Ca-calmodulin blockers chlor- promazine and trifluoperagine and the block could be removed by adding purified calmodulin to lo-' mol I-').That stimulation of calmodulin does not necessarily require Ca2' has been demonstrated in the case of cyclic-GMP-depen- dent protein kinase." Calmodulin affinity chromatography has been employed in l9 P. Cohen Eur. J. Biochem. 1980 111 563. *' A. L. Boynton J. F. Whitfield and J. P. MacManus Biochem. Biophys. Res. Commun. 1980,95 745. T. Yamaki and H. Hidaka Biochem. Biophys. Res. Commun. 1980,94727. Biological Chemistry -Part (iv) Enzyme Chemistry 35 1 the purification of (Ca” + Mg2+)-dependent ATPase from human erythrocyte membranes.** It is evident that much chemical and physical work is waiting to be done before all the reactions involving calmodulin as a regulator of cellular metabol- ism can be fully delineated. 3 Superoxide Dismutases The univalent reduction of molecular oxygen gives rise to the superoxide radical 02-, which is the conjugate base of the weak acid H02’ (pK = 4.8).Two superoxide anions can interact with the formation of hydrogen peroxide and oxygen 02-+ 02-+ 2H’ -+ H202 + 02 (3) All oxygen-metabolizing cells apparently contain metallo-enzymes that are capable of catalysing reaction (3),and these have been named the superoxide dismutases (EC 1.15.1.1).Just as the catalases and peroxidases have evolved to protect cells from the harmful effects of H202 so it is thought that the dismutases act as a protection against the much more reactive oxygen free-radicals. However that this is not the whole story is now clear since phagocytosis (the ingestion of particles and their destruction by certain cells) results in the abundant production of super- oxide.Such phagocytosis by leucocytes plays a major role in the combating of infections in man and animals.23 It is generally agreed that superoxide itself is not the main antimicrobial or anti-tumour agent but that its importance lies in its ability to react with H202to produce singlet oxygen and hydroxyl radical as shown in reaction (4). metal 02-+ H202 +lo2+ OH-+ OH’ (4) The development of our knowledge of the superoxide dismutase enzymes (SOD) has recently been reviewed.24 There are three distinctly different classes of super-oxide dismutases depending upon the metal content. Copper-zinc SOD was originally found in ox blood and has now been isolated from the cytoplasm of a wide range of animal and plant cells.The enzymes are all of molecular weights near 32 000 consist of two identical subunits and contain one atom of copper and one of zinc per subunit. The SOD isolated from prokaryotic cells was found to be a larger molecule with a molecular weight of 40000 composed of two identical subunits and containing one atom of manganese per molecule. The enzyme originally isolated from mitochondria is also a mangano-enzyme but it has a molecular weight of 80000 and is tetrameric. Subsequently an enzyme has been located in the cytoplasm which contains four manganese atoms per molecule. However it is dissimilar to the mitochondria1 enzyme which closely resembles the prokaryote enzyme and which has been cited as evidence for the symbiosis theory of the origin of mitochondria.The mangano-enzymes appear to be the most widely distributed being found in both eukaryotes and prokaryotes. Finally an iron- containing dimeric SOD has been isolated from bacterial sources. 22 K. Gietzen M. TejEka and H. U. Wolf Biochem. J. 1980 189 81. 23 J. A. Badwey and M. L. Karnovsky Annu. Rev. Biochem. 1980,49,695. 24 (a) I. Fridovich Ado. Enzymol. 1974 41 35; (b)I. Fridovich Annu. Rev. Biochem. 1975 44 147; (c) ‘Superoxide and Superoxide Disrnutases’ ed. A. M.Nicholson J. M. McCord and I. Fridovich Academic Press London 1977; (d)J. V. Bannister and W. H. Bannister Biochem. Educ. 1981,9,42. 352 C. A. Ross The assay of SOD activity presents formidable difficulties since the substrate the superoxide radical has a transitory existence and has to be generated in situ.Pulse radiolysis of pure water generates e-aqand the H' and OH' radicals. In the presence of oxygen 02-and HO,' will be produced ePaq+ o2+ 02- (k= 2 x 10'Ol mol-' s-') (5) H' + 02 -+ H02 (k= 2 x 10" 1 mol-'s-') (6) Formate doubles the yield of 02-and eliminates OH' as shown HCOO-+ OH' -+ COO-+ H20 (7) coo-+ 02 -* COZ + 02- (8) It is thus possible to introduce 02-into aqueous solutions to a concentration as high as 2 x moll-' and the rate constant for the reaction catalysed by bovine erythrocyte SOD was found to be 1.9 x lo91mol-' s-' by direct spectrophotometric monitoring. However more convenient indirect methods of assay have been developed whereby 0,-is generated enzymically by say the action of xanthine oxidase on xanthine in the presence of oxygen.The superoxide is scavenged by a suitable indicator molecule such as cytochrome c or nitroblue tetrazolium and SOD is detected by its ability to inhibit the modification of the detector. One unit of SOD activity can be defined as that which causes 50% inhibition of the modification under specified conditions. Differentiation between the copper-zinc and the manganese enzymes may be made on the basis of the sensitivity of the former to cyanide. To overcome these inherently difficult techniques radioim- munoassay has been de~eloped.'~ In the past year a number of primary structures has been reported. The Cu/Zn superoxide dismutase from human erythrocytes has been investigated by two groups,26 and the published amino-acid sequences are virtually identical with only two amino-acid differences (at positions 17 and 98).The resulting structure has been compared with sequence data for the enzyme from other sources and it shows a high degree of homology. The mammalian enzymes so far examined all have the N-terminal amino-acid blocked by an N-acetyl group. The main structural feature of the protein is a barrel formed by eight antiparallel 0-strands. The region from residues 17 to 30 which shows the most variability in sequence is located on the surface of the molecule and it may be related to the immunochemical properties of this class of enzymes. The amino-acid sequence of Cu/Zn SOD from bakers' yeast has also been as has that for the manganous enzyme from Bacillus stear~thermophilus.~~" In the case of the latter two identical subunits comprise 203 amino-acids each and they show 60% homology with the enzyme of Escherichia coli B.The predicted secondary structure indicates that it is unlike that of the Cu/Zn enzymes. 25 A. Baret P. Schiavi P. Michel A. M. Michelson and K. Puget FEBS Lett. 1980,112 25. 26 (a)D. Barra F. Martini J. V. Bannister M. E. Schinina G. Rotilio W. H. Bannister and F. Bossa FEBS Lett. 1980 120,53;(b) J. R. Jabusch D. L. Farb D. A. Kerschensteiner and H. F. Dentsch Biochemistry 1980,19,2310. '' (a)J. T. Johansen C. Overballe-Petersen B. Martin V. Hasemann and I. Svendsen Carlsberg Res. Commun. 1979,44,201;(6) H. M.Steinman J. Biol. Chem. 1980 255 6758; (c) C.J. Brock and J. E. Walker Biochemistry 1980,19 2873. Biological Chemistry -Part (iu) Enzyme Chemistry The metal-binding sites in the subunit of Cu/Zn SOD consist of clusters of four residues (His-61 His-69 His-78 and Asp-9 1) in an approximate tetrahedral arrangement around the zinc atom and His-44 His-46 His-61 and His-118 in a plane with the copper. N.m.r. studies on the bovine erythrocyte enzyme and on two isoenzymes from wheat germ28 have revealed substantial structural homology. It has been shown that zinc plays a structural role while copper is catalytically essential being alternately reduced and re-oxidized. The two subunits are capable of exhibiting the same activity when paired with a native partner or with a modified inactive partner and Fridovich could find no evidence for half-of -the-sites reac- ti~ity.,~ Other investigations into the nature of the active site have implicated Arg-143 in the catalytic process because the enzyme is rendered inactive when that residue is modified with phenylgly~xal.~' The presence of a guanidinium group in close (6 A) proximity to the Cu" is seen either as providing electrostatic guidance to the incoming 0,-or as proton conduction.Transfer of an electron from Cu' and of a proton from the arginine in the second half of the catalytic cycle would yield a leaving group H20- which would be protonated to H202 in solution. Alternatively modification of Arg- 143 may simply perturb the active-site region. A somewhat surprising result from perturbed angular correlation (PAC) of y-rays spectroscopy on a yeast Cu/Cd SOD derivative has shown that His-63 (equivalent to His-61 in the mammalian enzyme) is not simultaneously co-ordinated to both the Cu and Zn.31 Two 'cautionary tales' have come from the Fridovich laboratory at Duke Univer- sity Medical Center during the past year.32 The first concerns the possible discovery of an inhibitor of SOD activity.Since mammalian cells do not contain a ferro- superoxide dismutase but many prokaryotes do a very extensive search has been made to find an inhibitor of this enzyme which might well then act as a bactericidal agent. Pamoic acid (1)was proposed as one such compound and 2,5-dimethylphenol as another. However it has been shown that such compounds react with 0,-to yield radicals which can reduce the scavenging indicators that are used in a number of assay methods for SOD.When the compounds were tested on the inhibition of the 02-dependent generation of ethylene from methional by SOD they had no effect. The other re-examination concerns the putative superoxide dismutase activity CH I (1) 28 A. R. Burger S. J. Lippard M. W. Pantoliano and J. S. Valentine Biochemistry 1980 19 4139. 29 D. P. Malinowski and I. Fridovich Biochemistry 1979,18,237. 30 (a)D. P. Malinowski and I. Fridovich Biochemistry 1979 18 5909; (b)C. L. Borders Jr. and J. T. Johansen Biochem. Biophys. Res. Commun. 1980,96 1071. 31 R. Baner I. Derneter V. Hasemann and J. T. Johansen Biochem.Biophys. Res. Commun. 1980,94 1296. 32 (a)H. M. Hassan H. Dougherty and I. Fridovich Arch. Biochem. Biophys. 1980 199 349; (b)J. Diguiseppi and I. Fridovich ibid. 1980 203 145. 354 C.A. Ross of Fe-EDTA which has variously been reported as exhibiting 0.01 to 0.1% of the efficiency of the enzyme. Again it has been shown that the Fe-EDTA complex interfered with the usual assay methods of SOD activity i.e. those utilizing cyto- chrome c or nitroblue tetrazolium by inhibiting the xanthine oxidase activity. The complex does not catalytically scavenge 02-,as does SOD and it had no effect upon the method of assay involving the photo-oxidation of dianisidine. The lesson appears to be that a wide range of assay systems must be employed when evaluating inhibitors and mimics of superoxide dismutase activity.4 Enzyme Kinetics The eightieth birthday of Malcolm Dixon (18 April 1979) was honoured by the Molecular Enzymology Group of the Biochemical Society in the form of a Col- loquium the proceedings of which have now been published. In this publication Tipt~n~~ discusses the concept of kinetic mechanisms being advantageous in terms of specific metabolic functions of enzymes. New books devoted to the subject of enzyme kinetics (which have been so plentiful in recent years) have been virtually absent in 1980. A revised edition of Cornish-Bowden’s textbook (under a slightly different title34) arrived as did two volumes in the ‘Methods in Enzymology’ series devoted to enzyme kinetics and mechani~m.~~ The first of these deals with initial-rate methods and with inhibitor and substrate effects and it consists of twenty contribu- tions from many of the leaders in the field.The second volume comprises six articles on isotope probes and eight on complex enzyme systems including hysteretic and immobilized enzymes and co-operativity in enzyme function. We are promised more volumes edited by Purich in this series. With regard to kinetic data and analysis the debate continues on the best way to proceed. In a contribution to the ‘Textbook Errors’ series in Trends Biochem. Sci. Cha~lin~~ observes that one of the reservations made when deriving the Michaelis-Menten equation namely that substrate concentration always exceeds enzyme concentration to such a degree that ([So] -[ES]) [So] is unnecessarily restrictive.At high enzyme concentrations a modified Michaelis-Menten equation can be simply derived vo = vmax[s0l/(~m + [Sol + LEO]) (9) Chaplin has a point for in this day and age enzymes are frequently available in such purity and of known molecular weight that [E,] can be calculated. In a review article Atkins and Nimmo3’ have examined common approaches to determining the usual kinetic parameters and they favour the determination of initial velocities and analysing the data by least-squares treatment rather than attempting the analysis of progress curves. In contrast Fukagawa3* has published a computer program for 33 K. F. Tipton Biochem. SOC. Trans. 1980,8,242. 34 A. Cornish-Bowden ‘Fundamentals of Enzyme Kinetics’ Butterworths Boston 1979 [Reviewed by H.Gutfreund FEBS Lett. 1980,116 1251. 35 ‘Enzyme Kinetics and Mechanism Part A’ and ‘Enzyme Kinetics and Mechanism Part B’ ed. D. L. Purich ‘Methods in Enzymology’ Vol. 63 and Vol. 64 ed. S. P. Colowick and N. 0.Kaplan Academic Press New York 1979 and 1980. 36 M. F. Chaplin Trends Biochem. Sci. 1981,6 Jan. p. IV. 37 G. L. Atkins and I. A. Nimmo Anal. Biochem. 1980,104 1. Y.Fukagawa Biochem. J. 1980,185 186. Biological Chemistry -Part (iv)Enzyme Chemistry the analysis of the progress curve of a single reaction (obtained by spec- trophotometry) and has applied it to p-lactamase. Chou has described a new graphical method for simplifying the calculation of reaction rates of steady-state enzyme-catalysed The Lee and Wilson modification of the double-reciprocal plot has been re-e~amined.~’ It was claimed for this modified treatment in which the so-called log mean substrate concentration {([So]-[S,])/ln([S,]/[S,])} was replaced by the arithmetic mean substrate concentra- tion {([So] + [S,])/2} in the integrated Michaelis-Menten equation that the para- meters V,, and K could be determined with little error even when half of the substrate had been consumed in a reaction.This now appears not to be the case. The validity of the use of the ‘jack-knife’ statistical technique in analysing kinetic data for enzymes has been defended41 against criticism. Kohberger4’ has evaluated the Direct Linear Plot and has produced statistical evidence to show that whereas harmonic spacing of substrate concentrations is in general a more efficient experi- mental procedure it should be used with a weighted least-squares analysis.The Direct Linear Plot performs better with substrate values chosen in arithmetic spacing and has been used to evaluate individual rate and association constants.43 In the serine-protease-catalysed hydrolysis of substrate S added nucleophile (N) provides an alternative pathway as shown in Scheme 2. Additions of nucleophile K (PI P2 P3 are products) k EA+yL+p, E+S $ ES+ P1 Scheme 2 lead to decreases in k,, (which eqFals k2kz/kz+ k3)and to increases in K,. The intersection points (co-ordinates K and V) lie on a straight line with intercept K on the K axis and k3[Eo]on the V axis (see Figure 2).The rate constant of acylation k2,may be determined from the ratio a/b = k2/k3. So-called suicide substrates (mechanism-based inactivators) are useful as probes of active sites or in the search for effective drugs. It is characteristic of their action that formation of products and inactivation of enzymes proceed concurrently and in a constant ratio (the partition ratio) throughout the course of the reaction. Scheme 3 due to Walsh et al. (1978) where X and Y are enzyme complexes and Ei is inactive enzyme has now been analysed by wale^,^^ and rate equations for inactivation have been derived. E+S $ X+Y-*E+P L Ei Scheme 3 39 (a)K. C. Chou and S. Forsin Biochem. J. 1980 187 829; (b)K. C. Chou Eur. J. Biochem. 1980 113 195.40 N. G. Karanth and A. K. Srivastava Biochim. Biophys. Actu 1980,615 279. 41 A. Cornish-Bowden and J. T.-F. Wong Biochem. J. 1980,185 535. 42 R. C. Kohberger Anal. Biochem. 1980,101 1. 43 V.Dorovska-Taran and D. Raykova Biochim. Biophys. Actu 1980,615 509. 44 S.G. Waley Biochem.J. 1980 185 771. 356 C.A. Ross V A 1 I bl I >I I I I I I a1 I I I I 1 I I Figure 2 Determination of individual rate and association constants of hydrolysis in Eisenthal and Cornish-Bowden co-ordinates (1) without added nucleophile ;(2)and (3),with added nucleophile (Modified from Biochim. Biophys. Acta 1980 615 509) Non-hyperbolic behaviour of enzymes that bind ligands has received attention from a number of authors.Knack and R~hm~~ have developed a least-squares fit of the generalized Hill equation s = s,,,[L]"'L'/K + [LpL' (10) where the Hill coefficient is allowed to vary with [L] and is no longer treated as a constant. As a result curves for incomplete saturation may be analysed i.e. where S,, is unknown and the concentration dependence of Hill slopes that is arrived at may indicate more elaborate models for testing in specific cases. A review46 has been made of the usual graphical plots used in ligand-binding studies i.e. [bound]/[free] us [bound] [bound]/[free] us [free] and [bound]/[total] us [total] and the conclusion has been drawn that these can only provide a first approximation and that weighted non-linear least-squares treatment is required.In a novel approach to the estimation of the Hill parameters V and n) substrate was continuously added to a single reaction mixture and absorbance was analysed by a tangent-slope pr~cedure.~' A Gilford spectrophotometer has been suitably adapted to allow for the continuous addition of substrate to a stirred assay mixture and the absorbance changes were recorded encoded on paper tape. A number of enzymes has been investigated including immobilized lactate dehy- drogenase and the results obtained are in reasonable agreement with those already 45 1. Knack and K.-H. Rohm Biochim. Biophys. Actu 1980,614,613. 46 A. K. Thakur M. L. Jaffe andD. Rodbard Anal. Biochem. 1980,107,279. 47 D. J. LeBlond C. L. Ashendel and W. A. Wood Anal. Biochem..1980,104,355,370. Biological Chemistry -Part (iv) Enzyme Chemistry published. Finally in an extensive review48 of twelve enzymes out of some 800 which are said to exhibit deviations from Michaelis-Menten kinetics the conclusion is reached that at present without simplifying assumptions theoretical studies of involved mechanisms create equations of such complexity that it is virtually imposs- ible to interpret them in terms of K,, and V. 5 Enzyme Mechanisms Molybdenum and molybdenum-containing enzymes of which xanthine oxidase and dehydrogenase are examples have been the subject of recent reviews,49 and the kinetic mechanism of the xanthine-oxidizing enzymes has been re-examined.” These enzymes are dimeric and contain a molybdenum atom a flavin moiety and two iron-sulphur clusters in each subunit.The reducing substrate (xanthine) binds to the molybdenum and the oxidizing substrate (NAD’ or 0,) to the flavin; the iron-sulphur centres act as electron sinks. The generally accepted view was that these enzymes functioned in a classical ‘ping-pong’ manner (see Scheme 4) and indeed double-reciprocal plots did yield sets of parallel lines when one substrate was held at constant concentration while the other was varied and vice versa. This mechanism requires that the reducing substrate binds to the oxidized form of the enzyme and leaves as an oxidized product before the addition of the second substrate (oxidizing). However it has now been shown (by e.p.r.) that xanthine can bind to the reduced form of xanthine oxidase and (by spectrophotometry) that NAD’ can bind to the oxidized form of xanthine dehydrogenase.In consequence Coughlan and Rajagopalan’’ have proposed a ‘rapid-equilibrium random (two site) hybrid ping-pong’ mechanism such as has been proposed for the biotin-containing transcar- boxylase and they have applied Cha’s treatment to their scheme consisting of three rapid-equilibrium random segments (Scheme 5). The letter E represents the X U NAD’ NADH (X= xanthine; U =uric acid) Scheme 4 Scheme 5 48 W. G. Bardsley P. Leff J. Kavanagh and R. D. Waight Biochem. J. 1980,189 739. 49 (a)‘Molybdenum and Molybdenum-containing Enzymes’ ed. M. P. Coughlan Pergamon Press Oxford 1980; (6)‘Molybdenum Chemistry of Biological Significance’ ed.W. E. Newton and S. Otsuka Plenum Press New York and London 1980; (c) R. C. Bray Adv. Enzymol. 1981,51 107. 50 M. P. Coughlan and K. V. Rajagopalan Eur. J. Biochem. 1980,105,81. 358 C.A. Ross enzyme with the top and bottom bars denoting the molybdenum and flavin sites respectively. When all substrates and products are present there are eight possible complexes (and one form of the free enzyme) at each of the segments (see Scheme 6). From published data on a number of other enzymes the authors state their belief that many multi-component redox enzymes will be found to operate via such a two-site mechanism. Jp NAD + E" L_. NAD + u+E+x NAD + G -Ex + + + NADH NADH NADH Jp Jp Scheme 6 The control of the pentose phosphate pathway (hexose monophosphate shunt) is not well understood but it is generally agreed that the first committed step i.e.that catalysed by glucose 6-phosphate dehydrogenase (EC 1.1.1.49),is critical to such control. The mammalian enzymes are NADP-preferring and are inhibited by reduced coenzyme. In view of the high NADPH/NADP' ratios prevailing in many tissues it is of interest to ascertain how the enzymes can function at all let alone be controlled. Following reports that some glucose 6-phosphate dehydrogenases exhibit dual nucleotide specificity and that the kinetic mechanism differs for the NAD'-and NADP'-linked reactions the enzyme from lactating rat mammary gland has been in~estigated.~~ The authors are unable to state unequivocally that the mechanism is 'partial rapid-equilibrium random' and their explanation for the two classes of binding site for glucose-6-P appears to be at variance with their own evidence of competitive inhibition by NADPH with respect to both NADP' and NAD' indicating that there is only one catalytically active form of the enzyme.The kinetic mechanism of glutamate dehydrogenase (EC 1.4.1.3),previously considered to be random in both directions has been re-examined by Rife and Cleland.52 The forward reaction does indeed appear to be random with the nucleotide dissociating more rapidly than the amino-acid from the ternary complex. D. S. Shrere and H. R. Levy J. Biol. Chem. 1980,255 2670. 52 J. E. Rife and W. W. Cleland Biochemistry 1980 19 2321 2328. Biological Chemistry -Part (iv) Enzyme Chemistry L B A Scheme 7 In the reverse direction however the addition of keto-acid and ammonia to the enzyme-NADPH complex appears to be ordered and with the combination of nucleotide and keto-acid largely ordered as shown in Scheme 7 which correctly predicts the non-competitive or uncompetitive nature of substrate inhibition pat- terns.However ketoglutarate will combine with E-NADP' and so gives rise to the inhibitory E-NADP'-KG complex as well as combining with E-NADPH to give E-NADPH-KG to which ammonia binds. The two complexes occur in constant ratio as the ketoglutarate concentration is altered. The Scheme does not take into account the fact that NADP' can dissociate from the E-NADP'-KG complex and so allow the reaction to proceed as evidenced by the partial inhibition that is seen when the concentration of ammonia is varied.In a second paper the authors report the pH profiles for the binding of keto-acids and analogues to E-NADPH and show that a group with a pK of 5 (possibly carboxyl) has to be protonated for binding to occur and that a second group (possibly lysine) with a pK of 7.8 has to be protonated to bind the 5-carboxyl of dicarboxylic acids. The V/K profiles for ammonia indicate that the substrate is the neutral molecule and those for glutamate (or norvaline) show that the amino-group of the amino-acid needs to be protonated while a group (possibly lysine) with a pK of 7.6-8 in the enzyme must be unprotonated for activity. Based on these observations a mechan- ism is proposed in which there is direct attack of ammonia on ketoglutarate to give a carbinolamine with a lysine residue supplying a proton.The transfer of a proton from N to 0 of the carbinolamine (possibly catalysed by a carboxyl group) is followed by elimination of water and the resulting iminoglutarate is reduced by NADPH to glutamate. The reaction is completed by the protonation of the amino- group of glutamate by the catalytic carboxyl group (Scheme 8). From amino-acid modification studies it is known that the lysine residues 27 and 126 are unusually reactive and have low pK values (8.2 and 7.8 respectively). It is not yet possible to assign the catalytic role or the binding role to a particular lysine residue. Also from Cleland's laboratory have come reports5 of an elegant kinetic method for measuring dissociation constants of metal complexes with ATP and ADP.The '' (a)J. F. Morrison and W. W. Cleland Biochemistry 1980 19 3127; (b)R. E. Viola J. F. Morrison and W. W. Cleland ibid. p. 3 13 1. 360 C.A. Ross F+.+ HH I I I 00 0 o\c40 \/ 0\c/ I I I .wc IM. H HH I I 0\&0 0 -o\cl.p ac/0 I uI* I I Scheme 8 determination requires that the metal-ATP complex acts as an inhibitor of an enzyme which requires MgATP and it is the ratio of the dissociation constants for MgATP and inhibitory metal-ATP complex that is measured. Since the values of dissociation constants for MgATP under a wide variety of conditions are known the dissociation constant of metal-ATP can be readily calculated.Using the method with hexokinase the dissociation constants for EuATP and GdATP have been calculated. In the course of the work it has been confirmed that the apparent activation of hexokinase by citrate is due to the chelation of aluminium in AlATP which is a contaminant of commercial ATP to form aluminium citrate. 6 Phosphofructokinase Phosphofructokinase (EC 2.7.1.1 1) catalyses the phosphorylation of fructose 6- phosphate to fructose 1,6-bisphosphate [equation (1l)],and being the first com- mitted step in glycolysis is not unexpectedly subject to a high degree of regulation. fructose-6-P2-+ MgATP4-$ fr~ctose-1,6-P~~-+ MgADP3-+ H+ (11) The enzyme has naturally excited the interest of researchers since it was first reported by Dische in 1935 and continues to do so as evidenced by two recent reviews54 and a 54 (a) K.Uyeda Adv. Enzymol. Relat. Areas Mol. Biol.,1979 48 193; (b) A. R. Goldhammer and H. H. Paradies Curr. Top. Cell. Regul. 1980 15 109. Biological Chemistry -Part (iu)Enzyme Chemistry 361 number of important papers which have appeared during the past couple of years. Phosphofructokinases (PFK) from various mammalian tissues and from yeast and prokaryotes have been shown to differ in their physical and chemical properties. The mammalian enzymes are more complex; the smallest enzymically active form is a tetramer of molecular weight ca. 3.2-3.8 x lo5and of S20.w= 13 but aggregations occur by self-association of subunits dependent upon the concentration of protein.The latest available electron micrograph^'^" show the porcine liver enzyme to occur in tetramers under suitable dissociating conditions; a few octamers occur dimers are rare and hexamers are not seen. For this reason the authors argue that Figure 3 represents the most likely orientation of identical subunits since it alone features distinct isologous dimerdimer and tetramer-tetramer bonds. Lardy at Wisconsin has continued his long association with research on PFK by publishing observations on the aggregation of the enzyme as observed by fluorescence p~larization.~~ He has shown that MgATP or fructose 6-phosphate (Fru6P) are the dominant influencing ligands and that binding Fru6P shifts the equilibrium in favour of association.In a steady-state analysis of rat liver PFK Lardy has shown the enzyme to have an extremely low affinity and a high degree of positive co-operativity towards Fru6P (K,= 6 mmol I-*; Hill coefficient >4). Figure 3 Subunit interactions within phosphofructokinase. Arbitrarily assigned ‘top’ subunits are marked T;‘bottom’ faces are blank. Subunit-binding sets are marked with one two or three lines to show the orientation of each subunit ilt the plane of the page The existence of five isomers of human PFK has been demonstrated.” The liver and muscle enzymes are homotetramers i.e. L4 and M4 respectively but the enzyme isolated from erythrocytes is a heterogenous mixture of five isoenzymes arising from the association of L and M subunits. Another human isoenzyme F4 the fibroblast type has recently been reported and chara~terized.~~ It exhibits allosteric behaviour to a much lesser degree than the other enzymes in keeping with its occurrence in cells where the control of glycolysis is not of paramount importance.The phosphofructokinases exhibit regulatory behaviour towards both substrates and both products and they are activated by AMP ADP CAMP NH4+ and inorganic phosphate (and also sulphatessb) and are inhibited by citrate phosphoglyc- erates and creatine phosphate. In addition the activity of the enzyme appears to be controlled by aggregation (referred to above) and by phosphorylation. The ’’ L. G. Foe and J. L. Trujillo (a)I. Biol. Chem. 1980,255 10 537; (b)Arch. Biochern. Biophys. 1980 199,l.56 G.D. Reinhart and H. A. Lardy Biochemistry 1980,19,1484,1491,1477. 57 S.Vora C.Seaman S. Durham and S. Piomelli Proc. Narl. Acad. Sci. USA 1980,77,62. ’* M. C.Meienhofer D. Cottreau J. C. Dreyfus and A. Kahn FEBSLert. 1980,110 219. 362 C.A. Ross catalytic subunit of CAMP-dependent protein kinase is capable of phosphorylating a serine residue in a terminal sequence that has been isolated by limited proteolysis; the reaction is profoundly affected by the presence of allosteric ligand~.~' The binding of ATP to the enzyme has recently been extensively investigated by Kellett in York.60 Using techniques similar to those developed by Trentham for probing the kinases Kellett has used a fluorescent analogue of ATP namely 1,N6-ethano-ATP for use in stopped-flow fluorimetry.The binding of the probe (L) to the catalytic site is consistent with a two-step mechanism E + E* E* + L $ E*L in which there is interconversion of the enzyme from one form E to another E". The extent of the allosteric transition from the R to the T conformation as induced by the ATP analogue was determined from the amplitude of the slow phase of its fluorescence enhancement. The activators cyclic AMP and fructose 1,6-bisphos- phate decreased the amplitude while an inhibitor citrate increased it. The confor- mation of the enzyme itself was monitored by intrinsic protein fluorescence the R conformation having diminished fluorescence compared with the T conformation. MgATP exerted a complicated effect enhancement at low concentrations and quenching at high concentrations resulting from binding to the inhibitory site followed by allosteric transition.Enhancement reflects the extent of the transition and it involves tyrosine and tryptophan probably in the vicinity of the active centre. Quenching reflects occupancy of the inhibitory site and involves a tyrosine. The binding site for cyclic AMP has been investigated by Hammes61 and its distance from a reactive sulphydryl group has been measured by fluorescence resonance energy transfer. The nucleotide-binding site was labelled with FSBas A {Sf-[ p-(fluorosulphonyl)benzoyl]-2-aza-l,N6-ethenoadenosine} and the sulphydryl group with NBD-Cl (7-chloro-4-nitrobenzo-2,1,3-oxadiazole)tand DDPM {N-[4-(dimethylamino)-3,5-dinitrophenyl]maleimide}.The distance was found to be 28 A; Hammes had previously shown the distance between the sulphydryl group and the citrate-binding site to be 40 A.By covalent modification with p-fluorosulphonyl ['4C]benzoyl-5'-adenosine,a peptide has been isolated that contains a lysine residue that has been identified as being in the binding site for the allosteric activators CAMP AMP and ADP.62 The complete amino-acid sequence of the subunit of the PFK from Bacillus stearothermophilus has been reported from the laboratory of the late J.I. Harris (see also refs. 8 and 9).63 t [4-Chloro-7-nitrobenzofurazan. Senior Reporter] 59 P. T. Riquelme and R. G. Kemp J. Biol. Chem. 1980,255,4367. 6o D.Roberts and G. L. Kellett Biochem. J. 1979,183 349; 1980,189 561,569.61 D.W.Craig and G. G. Hammes Biochemistry 1980,19 330. 62 L.Weng R. L. Heinrickson and T. E. Mansour J. Biol. Chem. 1980,255 1492. 63 E.Kolb P. J. Hudson and J. I. Harris Eur. J. Biochem. 1980,108 587.

ISSN:0069-3030    

DOI:10.1039/OC9807700347

出版商:RSC    

年代:1980

数据来源: RSC

摘要:

Aalstad B. 80 Abdulla R. F. 173 Abe H. 20 Abe R. 185 Abelson J. 314 Abenhafm D. 128 Aberhart D. J. 293 Abeywichrema R. S. 61 Abraham E. P. 297 Abraham R. J. 152 Achmatowicz O. 33 Adam M. J. 12 Adam W. 105 139 181 183 200 Adapa S. R. 175 AnggHrd A. 340 Agawa G. T. 234 239 Ager D. J. 234 273 Agho M. O. 180 Agosta W. C. 101 152 Agresti A. 20 Ahlberg E. 80 81 Ahlbrecht H. 125 Ahmad M. U. 226 Aida T. 245 Aikawa M. 73 Akagi H. 197 Akam T. M. 121 264 Akhila A. 292 Akkerman 0. S. 223 Aksnes D. W. 11 Albers-Schonberg G. 294 Alberti A. 60 Albright J. O. 264 Alcock N. W. 167 Alcorn W. C. 170 Alden R. A. 348 Alder R. W. 82 Aldenveireldt F. C. 306 Aldridge D.C. 128 Alegria A. 55 Alex R. F. 9 Alexakis A. 131 271 Alger B. E. 343 Ah S. A. 269 Allais A. 279 Allen G. 310 Allen J. K. 296 Allen L. C. 19 Author Index Allen M. 9 Allinger N. L. 18 28 150 Almgren M. 103 Alper H. 109 213 216 246 263 Altenbach H.-J. 198 Altman L. J. 157 Altnau G. 229 Alunni S. 51 Alwis K. W. 49 Amatore C. 80 Ambartsumyan N. S. 321 Amble E. 277 Amchelle J. 228 Amma E. L. 10 Amrich M. J. Jr. 56 Amstutz R. 126 221 Anastasia M. 293 Anastassiou A. G. 158 196 Anciaux A. J. 76 Andersen K. K. 7 Andersen L. L. 189 Anderson A. G. Jr. 160 Anderson D. R. 103 Anderson J. A. 296 Anderson M. G. 298 Anderson S. 311 313 Anding C.293 Ando A. 20 178 Andre D. 122 Andrews G. C. 245 269 Andrus A. 285 Anet F. A. L. 152 199 Angelastro M. 191 Angelini G. 157 Anh N. T. 128 Annarelli D. C. 227 Annis G. D. 185 Antropiusova H. 148 213 Aoai T. 115 247 254 Aoki S. 241 269 Aoki T. 269 Aoyama H. 179 Aoyama T. 17 277 Apeloig Y. 23 24 55 74 220 Appel W. K. 101 ApSimon J. W. 138 Aragozzini F. 290 291 363 Aratani M. 185 Arcamone F. 185 Arduengo A. J. 55 Arentzen R. 310 314 319 Argyle J. 291 Arihara M. 124 Arimura A. 334 Arison B. H. 294 Armatis F J. Jr. 308 Arnaud R. 60 Arnett E. M. 42 Arnett J. 71 Arnold E. 28 Arnold T. H. 18 Amost M. J. 196 Arnott S. 314 Artavarris-Tskonas S.348 Arvanaghi M. 135 237 273 Asao T. 195 Ashby E. 65 107 219 223 Ashcroft M. R. 58 Ashendel C. L. 356 Askani R. 32 Astell C. 313 Atkins G. L. 354 Atkins R. L. 171 Atkinson T. C. 319 Auk B. S. 222 Auner N. 228 Avakyan V. G. 228 Avasthi K. 111 Avrith D. B. 341 Ayabe G.-I. 70 Aznar F. 225 Baba T. 111 Bac N. V. 295 Baccolini G. 170 Bachi M. D. 182 Bachman W. E. 177 Baciocchi E. 51 Back T. G. 244 247 256 Bada J. L. 348 Badwey J. A. 351 Backvall J. E. 114 226 Battig K. 33 265 Baez M. 313 Baeza J. 11 Bagheri V. 123 Bagus P. S. 18 Bailey T. F. 161 Baird M. C. 110 Baird N. C. 23 Bairdlarnbert J. 299 Baker R. 206 Balasubrahmanyam S.N. Balasubrarnanian T. M. 343 Balci M. 139 181 Baldwin J. E. 277 297 Baldwin J. J. 188 Baldwin S. W. 101 117 141 Balenovie K. 253 254 Ballenger J. C. 342 Balley T. 23 Bally T. 139 Balot G. 90 Ban T. 197 Ban Y.,85 Bandara B. M. R. 267 Baner R. 353 Bankier A. T. 311 Banks B. E. C. 332 334 337 341 Banks R. E. 68 Bannister J. V. 351 352 Bannister W. H. 351 352 Banthorpe D. V. 292 Baraniak J. 308 Baran-Marszak M. 305 Barany G. 328 Barbara P. F. 100 Barber J. 290 Barber J. J. 222 Barbier M. 297 Bard R. R. 167 Bardsley W. G. 357 Barek J. 81 Baret A. 352 Bargar T. M. 271 Barillier D. 246 Barlow M. G. 143 Barltrop J. A. 105 Barnette W.E.241 247 248 254 269,283 Barnum C. 274 Barr P. J. 308 Barra D. 352 Barrell B. G. 3 11 Barrett A. G. M. 109 170 258 259 Barrett G. C. 194 Barron P. F. 13 Barrow K. D. 296 Barth J. 134 Barthelat J.-C. 77 Bartkowiak F. 124 Bartlett P. A. 34 138 269 Bartlett R. T. 299 Bartmess J. E.,221 Bartoli G. 170 Barton A. E. 270 Barton B. D. 55 Barton D. H. R. 61 62 108 109 170 231 255 256 258 259 260 261 263 Barton D. L. 242 Barton T. J. 219 228 Bartsch R. A. 167 Basset J. M.,210 Basus V. J. 152 Bates G. S. 244 Batten R. J. 268 Battersby A. R. 296 297 Batwardharn B. H. 7 Bauer W. R. 322 Baumann B. C. 23 Baumberger R. S. 81 Bauschlicher C. W. Jr. 71 Baxter A.J. G. 184 Baxter R. L. 295 Bayer E. 325 Bayer M. 273 Bays J. P. 99 Bazzi A. A. 7 182 Beach D. L. 206 Beak P. 133 Bearder J. R. 293 Beatty H. R. 170 Beatty K. M. 224 Beaucage S. L. 316 Beauchamp P.S. 31 Beaulieu N. 41 Becker G. 231 Becker J. 73 74 194 Becker K. B. 146 265 Becker P. N. 114 211 273 Becker W. G. 96 Becker Y. 213 Beckhaus H.-D. 56 168 Beckwith A. L. J. 53 60 62 152 284 Bee L. K. 161 Begue J.-P. 37 Belec C. A. 43 Bell H. C. 173 Bell R. A. 131 193 Bell T. N. 77 Bellarny F. 28 Bellus D. 140 Bencze L. 75 Benk P. 277 Benn R. 161 Bennett J. N. 30 139 283 Benoit R. 334 Beranek J. 306 Bergbreiter D. E. 134 Bergrnan J. 193 259 260 261 Bergrnan R.G. 67 114 211 273 Bergsma J. P. 168 Berke H. 74 Berkovich E. G. 67 Bernardon C. 169 Bemdge J. C. 177 Berryhill S. R. 216 Author Index Berthod H. 20 Bertolasi V. 191 Bertrand G. 228 Bertrand M. 284 Bertz S. H. 274 Besson B. 210 Bestmann H. J. 21 140 264 277 285 Bethell D. 83 Bettes T. C. 157 Beugelrnans R. 167 Bewick A. 81 86 254 Beynon J. H. 336 Bhakuni D. S. 296 Bhattacharya A. K. 47 157 Biala E. 320 Bickelhaupt F. 146 160 223 298 Bickerstaff G. G. 348 Biellrnann J. F. 46 222 Bierrnan D. 174 Biesiada K. A. 73 Bijl W. A. A. J. 327 328 Biloski A. J. 113 Bilyard K. G. 144 Binkley J. S. 15 16 Binning R. C. Jr. 157 Birch A.J. 23 157 267 Bird T. G. C. 241 Birdsall D. L. 314 Birkofer L. 219 Birnbaurn G. I. 308 309 Bishop R. 146 Bishop R. D. 109 Bjorkrnan E. E. 114 Blackborow J. R. 163 Blackburn E. V. 59 Blackburn G. M. 136 Blacker H. 307 Blacklock T. J. 35 Blade-Font A. 133 Blais C. 263 Blakeley R. L. 165 Blanchard J. M. 126 Blanchard M. 210 Blank N. E. 161 Blanzat J. F. 46 222 Blaschke G. 138 Blatcher P. 196 237 Blazejewski J. C. 231 Blazer R. M. 307 Bleachley 0.T. 226 Bloch A. N. 189 Bloch R. 145 Block E. 7 182 233 Blocker H. 306 316 Blornberg C. 223 Bloodworth A. J. 224 Blount H. N. 54 Blount J. F. 28 72 147 248 Blount J. R. 188 Bloy V. 126 Blucher W.G. 163 Blundell T. L. 338 Author Index Boar R. B. 109 Bobbitt J. M. 86 Bobenrieth M. T. 320 Boche G. 154 Bock H. 21 228 Bodanszky A. 325 Bodanszky M. 325 Boeckmann R. K. Jr. 251 Bohlen P. 334 Bohm M. C. 28 147 307 Boehm P. 273 Boekelheide V. 18 Boll W. 242 Bogdanovic B. 206 Boger D. L. 239 Boggs J. E. 18 Boguski M. S. 348 Bohlmann F. 187 229 Bohme D. K. 47 Boireau G. 128 Bolster J. 190 Bombala M. U. 236 Bonitz G. H. 135 Bonneau R. 100 Bonnet G. 125 Bonnier J. M. 60 Booth B. L. 168 Booth H. 152 Borden W. T. 21 24 35 Borders C. L. Jr. 353 Bos H. J. T. 268 Bosco M. 170 Bossa F. 352 Bottomley W. E. 34 Bouas-Laurent H. 221 Bouffard F.A. 183 Boulton A. J. 192 194 Bouma W. J. 23 Bovill M. J. 18 Bowen J. R.. 294 Bower D. J. 32 Bowers J. 65 223 Bowling R. A, 228 Bowman W. D. 18 Boyd D. R. 176 Boyd G. V. 34 Boyd J. W. 83 Boyer S. K. 76 Boynton A. L. 350 Bradley C. V. 336 Bradshaw A. P. W. 292 Bradsahw J. S. 199 Brady W. T. 140 Brandes D. 154 Brandsma L. 120 268 Brannegan D. P. 197 Brassel B. 35 Brauman J. I. 37 Bray R. C. 357 Brazeau P. 334 Bregant N. 253 254 Bregman R. 161 Breitenbach R. 197 Brennan T. M. 197 Brereton R. G. 290 296 Breslow R. 46 Brettle R. 129 277 Brewster A. G. 255 Bridges A. J. 235 Bridson P. K. 320 321 Brieger G. 30 139 283 Brienne M.-J. 138 Bright H.J. 348 Brimacombe R.,322 Brimeyer M. O. 124 Bringmann G. 62 Brink L. 344 Brinker U. H. 72 Brittain J. M. 164 Britton D. 39 Britton G. 294 Brock C. J. 352 Brocker U. 198 Broka C. 314 Brookhart M. 72 74 Brooks B. R. 17 Brouillard R. 165 Brousseau R. 313 316 320 Brower K. R. 56 Brown C. 332 Brown E. 330 Brown E. G. 308 Brown F. R. Jr. 133 280 Brown H. C. 107 113 114 117 118 138 263 265 Brown J. M. 206 Brown L. R. 337 Brown S. E. 348 Brownbridge P. 186 Browne A. R. 72 Brownlee G. G. 312 313 Brownstein M. J. 343 Broxton T. H. 167 Bruck M. A. 308 Bruhin J. 159 Brunet J.-J. 112 204 Brunfeldt K. 319 Brus L. E. 100 Bryson T. A. 135 Buchanan A.C. 111 161 Buchanan J. G. 298 299 300 303 Buchardt O. 194 Buck H. M. 308 Buckley D. J. 247 Buckley E. 165 Buerkle W. 124 Buffoni F. 20 Buhro W. E. 193 Bumgardner C. L. 51 Bunce N. J. 168 Buncel E. 38 165 166 Bunnett J. F. 67 164 166 167 Bunting J. W. 200 Burch D. J. 220 Burdon J. 178 Burger A. R. 353 Burger D. H. 180 Burger U. 6 187 Burgess G. M. 332 Burgstahler A. W. 273 Burke M. C. 46 155 Burke S. D. 75 220 Burkhart J. P. 268 Burns G. T. 228 Burns M. K. 294 Burnstock G. 332 339 Burton A. 256 Burton G. 8 296 Bury A. 58 210 Buse C. T. 129 Busetta B. 337 Bussas R. 34 Butcher J. A. Jr. 73 Bykovsky V. Y. 297 Byrn S.R. 31 Bystrov V.F. 336 Cabelli M. D. 296 Cacace F. 168 Cadger T. 314 Cahiez G. 131 Cahill R. 295 Calas R. 171 229 238 Caldwell R. A. 29 Calienni J. 277 Callot H. J. 86 Cama L. 184 Camaioni D. M. 63 Cameron T. S. 10 Campagnon P. L. 90 Campbell I. M.,291 Campbell J. B. Jr. 11 7 118 265 Campbell M. M. 137 Cane D. E. 289 292 295 Canonica L. 294 Cantoni G. 189 Capozzi G. 34 Cappelli F. P. 52 Caramella P. 28 150 Caravana C. 322 Cardy H. 24 Caret R. L. 11 Carey N. H. 310 313 Carless H. A. J. 187 270 Carlsson H. S. 83 Carman R. M. 128 Carpenter B. K. 153 Carr D. B. 225 Carr R. V. C. 28 31 43 242 284 Carre J. C. 198 CarrC M.-C. 100 Carroll W. F. 146 Carruthers N.137 Carstairs J. R. 341 Carter R. H. 290 Cartwright E. M. 312 Cartwright I. L. 320 Carty A. J. 226 366 Caruthers M. H. 316 Cary L. W. 209 Casadevall A. 38 Casadevall E. 38 Case D. A. 18 Cashion P. 314 Casiraghi G. 169 Casnati G. 169 Caspi E. 293 Cassar L. 203 Castel A. 230 Catlin G. H. 310 Caubere P. 100 112 204 Cava M. P. 189 238 257 258 Cavender P. L. 292 Cech D. 306 Cere V. 144 199 Cerfontain H. 44 100 161 Chacon-Fuertes M. E. 303 Chadwick D. J. 18 152 Chahine J.-M. el H. 165 Chaloner P. A. 206 Chamberlin A. R. 237 268 Chambers G. R. 71 Chambers R. D. 178 Chamot E. 72 Chan A. S. C. 205 Chan C. 10 Chan D. M. T. 145 Chan T.H. 36 186 245 Chan W. K. 244 Chananont P. 308 Chandler A. 135 Chandler M. 145 266 Chandramouli N. 325 Chandrasekaran R. 314 Chandrasekhar J. 20 21 23 219 Chang C. C. 298 Chang C.-J. 298 Chang H. W. 236 Chang M. J. 160 Chang M. N. T. 40 Chang P. 293 Chang R. C. C. 334 344 Chapat J. P. 152 Chaplin M. F. 354 Chapman C. A. 334 341 Chapman K. T. 273 Chapman 0.L. 68 228 Chappuis J. L. 146 Charles G. 121 264 Charpentier-Morize M. 37 Charpiot B. 231 Charumilind P. 28 Chatgilialoglu C. 55 Chaturvedi R. 296 Chattopadhyaya J. B. 314 Chaussin R. 246 Chaves das Neves H. J. 302 Chaw Y. F. M. 321 Chen E. 3 11 Chen Y.-Y. 188 279 Cheng C.-C. 312 Cheng J.C.-P. 34 Cheng T. S. S. 298 Cherest M. 128 Chermprapai A. 135 168 Chernov B. K. 319 Cheung W. Y. 348 Chi Y. 117 Chiang L.-Y. 189 Chiang S.-H. 95 96 Chiang W. 96 Chien D. H.-T. 100 Childs R. F. 35 95 Chin E. 278 Chittatta G. J. 248 249 252 257 268 Chiu P. 313 Cho H. 237 268 Choe J.-I. 154 Choo K. Y. 57 228 Chottard J.-C. 5 Chou K. C. 355 Choudhury A. M. 326 Chow F. 247 250 252 Christensen B. G. 183 184 Christensen J. J. 167 194 Christiansen P. A. 17 Christoffersen R. E. 19 20 Chu C. K. 303 Chu N. G. 186 Chuaqui C. 38 Chuit C. 274 Chujo Y. 274 Church D. F. 57 Cicero T. J. 343 Cighetti G. 293 Cimarusti C. M. 236 Cimino G. G. 164 Cipris D.94 Clague A. R. 180 Clancy M. G. 69 Clardy J. 28 Claremon D. A. 247 251 269 274 Claret M. 332 Clark D. A. 270 289 Clark J. A. 138 Clark T. 20 24 45 161 219 220 Clarke J. K. A. 210 Clarock R. 224 Clegg W. 30 Cleland W. W. 358 359 Clement A. 75 Clementi E. 15 20 Clerici M. G. 115 Clifford D. P. 163 Clive D. L. J. 111 233 247 248,249,252,257,259,268 Close D. 178 Coates R. M. 41 292 Cocks T. M. 332 Coderre J. A. 308 Coe D. E. 86 254 Author Index Coffin J. M. 294 Cogolli P. 61 Cohen G. L. 322 Cohen M. L. 249 Cohen N. 126 Cohen P.,350 Cohen S. G. 99 Cohen S. N. 321 Cohen T. 237 Coleman J. P. 89 Collet A. 138 Colley P. W. 296 Collier K. J.314 Collins J. B. 16 23 219 Collins J. J. 33 Collins S. 247 256 Collum D. B. 187 269 Colombo L. 290 291 Colvin E. W. 271 Conrad P. C. 242 Content J. 310 Cook A. F.,299 Cook E. A. 313 Cook M. 18 Cook P. D. 301,305 Cooke F. 236 Cooksey C. J. 58 Cookson R. C. 234,235,240 266,273 Coon C. L. 171 Cooper L. 134 Coppola G. M. 197 Corbett D. F. 277 Corcoran J. W. 244 Corey E. J. 230 237 264 268,270,271,273,279,280 289 Corkins H. G. 180 182 Cormier R. A. 76 Cornelius J. 168 Cornett B. J. 57 228 Cornish-Bowden A. 354 355 Corongiu G. 20 Cory R. M. 145 242 Cossement E. 185 Cossey A. L. 277 Costa M. 339 Cottreau D. 361 Coughlan M. P. 357 Coulson A.R. 3 11 Court J. 60 Courtney P. M. 180 Cousseau J. 121 Cowan D. O. 189 Cowell A. 208 279 Coxon D. T. 302 Coy D. H. 328 333 344 Craig D. W. 362 Cramp M. C. 266 Crampton M. R. 164 Crandall J. K. 285 Crane L. E. 321 Crans D. 24 Author Index Crass G. 126 Cravador A. 256 Crawford J. L. 314 Crawford R. J. 33 Crawford T. C. 269 Craze G.-A. 48 153 Crea R. 310 319 Creary X. 73 167 Creighton T. E. 333 Cremer D. 23 Cromarty F. M. 170 Crombie L. 294 Cross A. W. 280 Cross B. E. 293 Crouch T. H. 348 349 Crouse G. D. 36 140 Crout D. H. G. 295 Cuong N. K. 272 Cupas C. A. 164 Curran D. P. 144 Curtis N. J. 248 249 252 257 268 Cussans N. J. 256 Czarny M.R. 256 Daddona P. E. 295 Dahan F. 75 Dqmbska A. 11 Damrauer R. 199 Daney M. 221 Danheiser R. L. 36 Daniewski W. M. 237 Danishefsky S. 242 278 282 Dannenberg J. J. 39 Dardis R. E. 135 Dargelos A, 24 Darling D. S. 298 Darlington W. H. 208 Darst K. P. 269 270 Das J. 273 Das M. K. 129 Das P. K. 99 Daskalov H. P. 307 316 Daub G. W. 317 Dauben W. G. 36 95 96 Dauphin G. 181 Davidson E. R. 17 21 24 Davidson I. M. T. 77 Davidson J. G. 76 193 207 Davies A. G. 53 58 154 Davies A. M. C. 302 Davies J. S. 194 Davies L. P. 299 Davies P. D. 188 Davis A. P. 31 Davis A. R. 313 Davis E. R. 54 Dawson W. H. 12 Day A. C. 105 Day R. A. 89 Dayrit F. M.225 Deacon G. B. 224 Deanne D. M. 340 Deberly A. 169 De Bruijn M. H. L. 311 De Buys Scott 291 DeCicco G. J. 74 De Clercq E. 310 Declercq J.-P. 181 246 Dedman J. R. 348 Deger H. M. 147 159 De Graaf W. 168 Degrand C. 90 Dehler W. 301 Dehmlow E.V. 119 Deisenhofer J. 338 De Jesus A. E. 291 Dekerk J.-P. 180 de la Mare P. B. D. 164 Delaney M. S.,205 Delange R. 169 Delaroff V. 279 DeIBris G. 238 Della E. W. 61 Dellacoletta B. A. 166 De Lucchi O. 105 139 200 De Lullo G. C. 281 de Mayo P. 103 105 182 de Meijere A. 71 139 Demeter I. 353 Demonceau A. 76 Dempsey C. E. 332 337 Demuth M. 98 Demuynck J. 23 70 Denis J.-M. 145 Denis J. N. 109 Deniff P. 289 Dentsch H.F. 352 DePriest R. N. 65 223 Dequeil-Castaing M. 230 Derbyshire R. B. 307 316 320 de Renzi A. 212 de Rooij J. F. M. 316 de Ruiter R. 90 Derynck R. 310 Desai S. R. 241 Deshpande M. N. 180 Deslauriers R. 309 Deslongcharnps P.,41 De Tar M. B. 146 Detty M. R. 247 252 Deutch J. 222 de Villardi G. C. 11 Devlin M. C. 342 Devos R. 310 Dewar M. J. S. 18 22 Dewey H. J. 159 Dewick P. M. 295 de Wied D. 342 de Wolf W. H. 146 160 Dhathathreyan K. S. 10 Di Augustine R. P. 340 Dick B. 159 Dickerson R. E. 314 Dickson M. K. 209 Diguiseppi J. 353 Dike M.,141 Dike S.,141 Dimaline R. 341 Dinur U. 17 Dipple A. 307 Ditner D. C. 7 Divakar K. J. 304 Dixt A.S. 174 Dixit V. M. 79 Dixon A. J. 268 Dixon D. A. 219 Dixon M. 347 Doba T. 99 Dobashi A. 130 Dobrynin V. N. 319 Dockray G. J. 326 341 Dodd J. 28 150 Doddrell D. M. 13 Doecke C. W. 29 Dohling A. 160 Doehner R. F. 147 Doehnert D. 24 Doel M. T. 313 Doel S. M. 310 Doerfler D. L. 291 Doerjer G. 161 Dolphin J. M. 196 Dombek B. D. 209 Domelsmith L. N. 28 150 Donaubauer J. R. 234 Dondoni A. 191 Dorovska-Taran V. 355 Dorschel C. A. 295 Dougherty H. 353 Douglas A. W. 294 Douglas J. E. 18 308 Dow R. L. 123 Dowlatshahi H. A. 61 108 263 Downey W. G. 21 Doyle M. P. 76 123 170 193 207 Dreiding A. S. 179 Dreier F. 187 Drengler K. A. 41 292 Drew H.314 Drew S. M. 103 Dreyfus J. C. 361 Drossard J.-M. 198 Drouin J. 3 11 Dubac J. 228 Diirr H. 73 Dufresne R. 296 Dull T. 310 Dumartin G. 230 Dumont W. 250 252 256 Duncan D. P. 227 DunEia J. V. 32 116 265 Dunitz J. D. 39 221 Dunkin I. R. 68 Dunogues J. 171 229 Dupont W. A. 277 Duque C. 294 Durham S. 361 Dworkin A. S. 161 Dyer T. A. 312 Dyke A. F. 75 Dykstra C. E. 22 Eaborn C. 224 228 Earl R. A. 305 306 Easton C. J. 53 152 284 Eaton M. A. W. 310 313 Eaton S S. 12 Eberbach W. 198 Eberson L. 82 92 Eby S. 199 Eckers M. 221 Eckert-Maksic M. 159 Eder U. 240 Edgar A. R. 299 303 Edge M. D. 319 Edwards B. 76 Edwards P. D. 186 Edwards S.L. 348 Efcavitch J. W. 316 Effenberger F. 37 161 Effio A. 63 Egert E. 307 Eggertand J. H. 298 Egli H. 34 Eglington A. J. 277 Eguavoen O. 166 Ehler K. W. 305 Eichin K. H. 168 Einck J. A. 307 Eisenberg D. 338 Eisenstein O. 49 128 Eisenstein S. 298 Elliott M. L. 197 Elliott R. C. 193 Ellis P. D. 10 Ellison R. H. 71 El-Shafie S. M. M. 39 Elyakova E. G. 336 Emmick T. L. 173 Emmons W. D. 171 Emokpae T. A. 166 Emtage J. S. 310 Encinas M. V. 99 Enders D. 125 236 Endo T. 306 Engel P. S. 53 95 138 England W. B. 38 Englert G. 294 Engman L. 259 260 261 Enoxida R. 227 Entwistle I. D. 252 273 Eperon I. C. 311 Ericsson A. 3 Eriksson B. 348 Erisman M.D. 340 Ernst L. A. 291 Erskine R. W. 26 Erspamer V. 344 Esaki K. 163 Esch F. 334 Estes D. W. 220 Estreicher H. 230 271 Eustache J. 196 Evans D. A. 36 128 129 211 214 234 245 269 Evans D. F. 11 Everard J. E. 165 Everett J. R. 152 Expert-Bezancon A. 322 Ezike J. 71 Factor R. E. 96 Fagerness P. E. 8 296 Faggiani R. 322 Fahr E. 70 Fahrenkrug J. 339 Falck J. R. 264 Falcone S. J. 258 Falsig M. 91 Familletti P. C. 310 Fantes K. H. 310 Farachi C. 187 Farb D. L. 352 Farina J. S. 32 196 Farina V. 248 249 257 268 Farooqi J. A. 162 Fasold H. 322 Fauth D. J. 112 Fava A. 144 199 Favre A. 132 Federsel H.-J. 193 Fedorynski M. 73 Fedotov M.A. 9 Fedryna C. 166 Felix G. 229 Felker D. 219 Felkin H. 128 Feller D. 17 24 Fellows C. A. 226 Fellows R. E. 331 Femec D. A. 26 47 Fenwick G. R. 302 Ferezou J.-P. 297 Ferramola de Sancovich A. M. 297 Ferrier B. M. 342 Fiala R. E. 189 Fiat D. 9 Fiaud J. C. 282 Ficini J. 281 Fiebig A. E. 178 Fiecchi A. 293 Fiedler H. P. 301 Field D. J. 35 Field J. 13 Field L. 233 Fields K. W. 46 155 Fields S. 3 13 Fiers W. 310 Fieser L. F. 174 175 Figdore P. E. 38 Figeys H. P. 181 Author Index Filippone P. 293 Filler R. 178 Fillion H. 122 Finas F. 320 Fink G. 322 Finnan J. L. 318 321 Finsin L. 194 Finzel R. B. 43 Firestone R. A. 56 Firmin J. L. 302 Fischer A.163 Fischer P. 163 Fischer R. G. 168 Fischer R. H. 271 Fisher E. F. 316 Fisk T. E. 158 160 Fitch P. M. 109 Fitt J. J. 277 Fitzsimons J. T. 341 Fleischhauer I. 72 Flemal J. 246 Fleming I. 229 235 Fliszar S. 157 Flood J. 170 Flood T. C. 74 Floss H. G. 289 296 298 Flynn G. A. 188 Fobare W. F. 170 Foe L. G. 361 Fogarasi G. 18 Foglio M. 185 Fookes C. J. R. 296 Foate C. S. 105 Forch B. E. 159 Ford T. M. 113 Forlani L. 191 Forrester J. 177 Forsen S. 355 Forsyth D. 84 Forsyth D. A. 158 Fortunak J. M. 117 217 266 Fossey J. 60 Fothergill L. A. 342 Foulger B. E. 177 Foulou J. P. 274 Fountain K. R. 162 Four P. 273 Fowler F. W.195 Fox D. J. 23 70 Fox J. J. 303 308 Fraenkel G. 220 221 222 Fraga B. M. 293 Franceschi G. 185 Franck R. W. 31 Franke W. 23 Franz J. A. 63 Fraser-Reid B. 131 265 Fredholm B. 340 Freer S. T. 348 Frejd T. 257 French J. C. 301 Frey M. H. 8 Fridovich I. 351 353 Author Index Friedrichsen W. 186 Frolich W. 159 Fruton J. S. 347 Fu P. P. 174 204 Fuchs P. L. 31 236 242 Fuhr K. H. 173 Fuhrman F. A. 299 Fuhrman G. J. 299 Fujhara H. 60 Fujii H. 194 Fujii T. 274 276 305 Fujii-Kurijama Y. 310 Fujimari K. 272 Fujisawa T. 131 Fujita E. 237 293 Fujita R. 195 Fujita T. 293 Fujita Y. 275 Fujiwara Y. 222 Fukagawa Y., 354 Fukui K. 74 Fukunaga T.22 Fukuzawa S. 259 Fukuzumi S. 58 65 231 Fuller C. W. 348 Fuller G. B. 86 254 Fulton R. P. 204 Funabiki T. 58 Fung A. P. 7 Fung C. W. 162 224 Fung N. Y. M. 103 Funk R. L. 30 139 207 278 283 Furness J. B. 339 Furui S. 247 Furukawa S. 282 Fushiya S. 129 Fykes D. L. 163 Gadaginamath G. S. 176 Gab S. 177 Gait M. J. 312 313 314 317 319 320 Gajewski J. J. 35 160 Gajewski R. P. 173 Galardy R. E. 337 Gallagher P. T. 68 Galli C. 170 189 Galli G. 293 Galli-Kienle M. 293 Gallo C. J. 22 Gallois P. 112 204 Galsworthy P. J. 83 Gammie L. 57 228 Gamill R. 242 Gancarz R. A. 247 256 Gandhi S. S. 166 Gandour R. W. 22 Ganem B. 113 197 Gani D. 59 Ganis P.212 Gano J. E. 100 Garcia-Luna A. 135 Gar’kin V. P. 253 261 Garland W. A. 197 Garratt P. J. 144 161 Garson M. J. 289 290 Garvey D. S. 245 269 Gaset A. 217 Gaspar P. P. 57 72 73 228 230 Gassmann P. G. 40 41 146 161 Gates B. C. 209 Gaudemer A, 305 Gauldie J. 332 Geckle M. J. 220 221 222 Geise H. G. 18 Geiselmann J. 56 Gemeiner M. 326 329 Genet J. P. 281 Gennari C. 290 291 Georgiadis G. M. 221 237 Georgian V. 76 Geraldes C. F. G. C. 12 Gerber L. D. 344 Gerdes H. 146 Gerhardt G. 162 Gerlach H. 132 Gerlt J. A. 18 308 Germain G. 181 246 Germon C. 271 Gerson F. 79 159 Gesing E. R. F. 207 Ghali N. I. 175 Ghangas G. 313 Ghiaci M. 199 Ghisalberti E.L. 289 Ghosez L. 181 185 Ghosh P. K. 312 Giacomello P. 168 Gibbs N. 308 Gibson B. 164 Gibson M. S. 166 Giddings P. J. 248 Gielen M. 219 230 Giese B. 71 Gietzen K. 351 Gil-Av E. 130 Gilbert A. 177 Gilbert B. C. 55 Gilbert W. 311 322 Giles J. R. M. 55 Gilham P. T. 314 Gill B. 55 Gill H. S. 178 Gillam S. 313 Gillard M. 39 Gillen M. F. 308 317 321 Gillen M. J. 136 Gillis H. R. 284 Gilman S. 247 257 Ginke F. 273 Ginsburg H. 167 Gitterman A. 296 298 Glass L. E. 49 153 Glasscock K. G. 58 Gleiter R. 28 29 149 159 Glover. S. A. 261 Gluchowski C. 134 Gneuss K. D. 297 Goad L. J. 293 Goddard J. D. 17 25 77 Goddard R. J. 74 Goddard W. A. 26 27 104 Godfrey M.158 Godleski S. A. 235 Godschalx J. 230 Goeddel D. V. 310 Goehring R. R. 106 190 Goehring W. 326 Goel A. B. 65 Goff H. M. 11 Gold J. M. 269 Gold P. 342 Gold V. 165 Goldberg O. 182 Golden D. M. 56 Golder W. S. 294 Goldfield E. M. 19 Goldhammer A. R. 360 Golding B. T. 64 Gol’ding I. R. 120 Goldman T. D. 98 Goldmann S. 239 Goldstein A. 344 Goldstein E. 18 Goldstein M. 340 Goldwhite H. 54 231 Gonnella N. C. 238 Gonzalez D. 32 115 265 Gonzalez F. G. 303 Gooch E. E. 270 Goodwin F. K. 342 Goodwin T. W. 293 294 Gopalan R. 235 240 Gordon E. M. 236 Gordon K. M. 233 Gordon M. S. 21 Gore P. H. 162 Gorenstein D. G. 19 Gorin F. A. 343 Gorst-Allman C.P. 291 Gosden C. 93 Gosteli J. 184 Goto G. 289 Goto T. 216 242 Gough G. R. 314 Gougoutas J. Z.,236 Gould S. J. 298 Goyal R. K. 339 Grabley S. 181 Grabowski J. 157 Gracy R. W. 334 Graf W. 237 263 Graham G. D. 20 219 Gramatica P. 294 Grandbois E. R. 126 Grandjean J. 4 Grant D. M. 307 Granter C. 49 370 Gray M. D. M. 136 Grayson J. I. 188 Grayston M. W. 143 Grdina M. J. 27 Green M. M. 84 Greenberg D. P. 96 Greene A. R. 319 Greene F. D. 28 192 Greenhough T. J. 101 167 Greenlee W. J. 244 Gregory R. A. 326 341 Gregson R. P. 4 299 Greiciute D. 236 Greven H. M. 327 328 Grey R. A. 204 Grieco P. A. 75 247 257 Grieser F.103 Griffin G. W. 22 73 Griffith E. H. 10 Griffiths J. 103 Griffiths L. 152 Grigg R. 140 207 Griller D. 53 63 Grimme W. 32 Grissom F. E. 331 Grobe J. 228 Grobel B.-T. 236 Gronowitz S. 190 Groombridge C. J. 8 Gross A, 182 Gross M. 86 310 Grossi L. 54 Groutas W. C. 219 Grubbs R. H. 211 Gruter H.-W. 175 Griitzmacher H.-F. 67 Grutzner J. B. 45 154 Gschwend H. W. 277 Guenzi A. 199 Gueritte F. 295 Guest M. F. 54 Guibe F. 276 Guida W. C. 187 Guillemin R. 334 Guingant A. 282 Gunning H. E. 76 Gunther H. 147 Guo W. 73 Gupta B. D. 58 Gupta B. G. B. 137 237 270 273 Gupta R. C. 312 Gupta S. 296 Gurbanov P. A. 236 Gusel’nikov L. E. 228 Gustafson-Potter K.E. 296 Gutekunst G. 231 Gutfreund H. 347 Gutierrez C. G. 58 Gutowsky R. 228 Guy A. 307 316 320 Gynane M. J. S. 54 226 227 231 Haack J. L. 175 Habib M. M. 112 Hachem K. 213 Haddadin M. J. 191 Haddon R. C. 19 22 Haenel M. W. 161 Harter P. 74 Hafner K. 22 159 Hagen J. P. 128 269 Hagiwara D. 185 Haglund U. 339 Hahn C. S. 188 Haiml L. 346 Haky J. E. 6 Halazy S. 250 266 Hales N. J. 67 Halgren T. A. 35 Hall C. R. 138 Hall I. H. 129 Hall L. D. 12 Halle J. C. 165 Halpern A. M. 177 Halpern J. 205 Halverson A. M. 98 Ham. P. 145 266 Hamada Y. 269 Hamaguchi H. 88 Hamaguchi M. 165 Hamberger B. 340 Hamblin M. R. 298 300 Hamill W.D. Jr. 307 Hamilton H. 89 Hamilton R. 148 Hamlyn P. H. 312 Hammarstrom S. 289 Hammerschmidt E. 160 Hammes G. G. 362 Hamor T. A. 68 308 Hanack M. 157 Handa K. 94 Handoo K. L. 83 Hanessian S. 132 Hannah D. J. 89 237 Hannan T. J. 343 Hannick W. D. 210 Hanrahan S. M. 38 Hansen R. T. 225 Hanson J. M. 332 Hanson J. R. 289 292 293 294 Hanson P. 200 Hanus V. 148 213 Hara S. 130 276 Harada T. 206 Hardenstein R. 109 Harding L. B. 25 26 27 104 Hardy P. M. 325 Hare P. E. 130 Hargrave K. D. 129 Harirchian B. 235 Harle H. 174 Harmony M. D. 154 Harms K. 30 Author Index Harper D. A. R. 228 Harpp D. N. 236 245 Harris J. I. 348 362 Harris R. K. 8 9 Harris T.M. 155 Harrison J. F. 70 Hart H. 67 174 Hart R. W. 175 Hartcher R. 151 Hartgerink J. 110 Hartley B. S. 334 Haruta J.-I. 34 276 Harvey R. G. 174 175 204 255 Haselbach E. 23 Hasemann V. 352 353 Hashiguchi S. 142 234 Hashimoto H. 115 277 Hashimoto M. 185 Haslam E. 37 276 Hass W. 301 Hassan H. M. 353 Hassner A. 181 Haszeldine R. N. 143 168 Hata T. 305 307 316 Hatanaka I. 253 Hatano S. 70 Hatate M. 86 Hatch R. L. 126 Hathway D. E. 174 322 Havinga E. 168 Hawthorne M. F. 205 Hayakawa K. 189 Hayase Y.,244 Hayashi M. 125 302 Hayashi S. 120 348 Hayashi T. 110 184 214 264 Hayes D. 322 Hayes D. M. 197 Hayes P. C. 68 Haymore B. L. 167 Haywood D.J. 187 270 Heaney H. 67 Heathcliffe G. R. 319 Heathcock C. H. 128 129 269 Hebblethwaite E. M. 185 Hebel P. 147 Heckendorf A. H. 295 Hedden P. 293 Hegarty A. F. 135 Hegedus L. S. 208 Heggs R. P. 113 Hehre W. J. 16 23 25 Heilbronner E. 18 21 153 Heinicke J. 23 1 Heinrichs M. 222 Heinrickson R. L. 362 Heinze P. 162 Helgee B. 80 Helsby P. 163 Hemmerich P. 348 Hemmes P. 307 Author Index 371 Hemmi K. 185 Henberger C. 263 Henderson G. N. 163 Hendrickson J. B. 32 196 Henriet M. 181 Henry P. 203 Henry R. A. 281 Hensel M. J. 31 Hentges S. G. 214 Herbert R. B. 200 295 Herd K. J. 188 Hernandez M. G. 293 Herold T. 141 Hershberger J.224 Hershberger S. S. 207 Herz C. P. 160 Hesabi M. M. 69 Hess B. 313 Hevesi L. 247 250 256 Hewett A. P. W. 152 Hewitt J. M. 222 Heyneker H. L. 310 Hiatt R. 57 Hibino S. 112 205 268 Hidaka H. 350 Hider R. C. 337 Hieter P. A. 348 Higashijima T. 301 Hill G. L. 222 Hillen W. 307 Himmele W. 203 Hinde A. L. 23 157 Hinney H. R. 242 Hino K. 275 Hirai K. 213 215 234 Hirakawa K. 176 Hirama M. 245 Hirao A. 126 Hirao K. 25 148 Hirata T. 295 Hiroi K. 237 Hiroto K. 195 Hirsch E. 139 276 Hirschler M. M. 162 Hirst D. M. 167 Hirst J. 166 Hirzel T. K. 98 Hishida K. 177 Hitchcock P. B. 228 Hiti A. L. 313 Ho T.-L. 136 Hoberg H. 225 Hocking J. D. 348 Hokfelt T.340 Hoekstra J. W. 193 Hoeller R. 21 Hoesch L. 179 Hofelich T. C. 157 Hoff W. S. 171 Hoffman R. V. 109 Hoffmann H. M. R. 142 Hoffmann R. 49 74 Hoffmann R. W. 73 269 Hofle G. 295 Hohlneicher G. 159 Hokari H. 115 Holak T. A. 11 Holden I. 294 Hollinshead I. M. 163 Hollinshead J. H. 67 Hollowood F. S. 148 Holm A. 130 Holmes W. 310 Holrock B. G. 70 Holy A. 306 Hommes H. 120 Honda K. 293 Honer D. P. 298 Hong Y.-M. 336 Hongo H. 195 Honig B. 17 Hood L. E. 326 334 335 344 Hook J. M. 173 Hoover D. J. 191 Hooz J. 274 Hopf H. 18 159 161 Hopkins P. B. 236 Hopkinson A. C. 21 Hopla R. E. 293 Hopper S. P. 228 Horak V. 157 Horhammer R.298 Hori T. 247 Horn T. 319 Hornback J. M. 95 Hornemann U. 298 Horton W. J. 307 Horwell D. C. 188 Hoshino O. 237 Hosomi A. 277 Hosozawa S. 296 Hotta K. 105 Hotta Y. 224 243 Houghton M. 310 Houghton R. P. 211 Houk K. N. 18 22 28 71 150 House H. O. 146 175 Hout R. F. 25 Howard A. E. 154 Howard J. A. 53 Howard S. I. 126 Howden M. E. H. 32 Howe I. 336 Howells P. N. 281 Hoyano Y. 292 Hoye R. C. 161 Hozumi T. 310 314 Hruska F. E. 309 Hsieh D. P. H. 291 Hsiung H. M. 313 316 320 Hsu C. C. K. 12 Hua D. H. 237 268 Huang S.-P. 184 Huang T. 319 Huang W.-Y. 334 344 Hubbard J. L.. 113 Hubbard J. S. 158 Hubbs J. C. 34 141 Huber R. 338 Huber W.53 Hubert A. J. 76 Huddleston J. A. 297 Hudgins W. R. 307 Hudrlik A. M. 265 278 Hudrlik P. F. 132 265 278 Hudson A. 54 231 Hudson P. J. 362 Hughes J. 342 Hugli T. E. 338 Hugues F. 210 Huguet J. L. 250 Hui R. A. H. F. 256 Huisgen R. 28 150 200 Hum G. P. 163 Humbel R. E. 338 Humphrey M. B. 72 Hunkapiller M. W. 326 334 335 344 Hunkler D. 181 Hunter D. H. 12 Hurley L. H. 298 Hussain S. 103 Husson H.-P. 295 Husstedt U. 112 Hutchins R. O. 204 273 Hutchinson C. R. 295 Hutchinson D. W. 320 Hutchinson R. J. 299 303 Huzinaga S. 16 Hwang K.-J. 251 Hwang T. 78 Ibrahim I. T. 50 Ibuka T. 274 Ichihara A. 283 Ichikawa K.,226 Ichimura H. 243 244 Iddon B.68 Igolen J. 306 Ihara M. 184 Iida H. 171 Ikawa T. 213 215 Ikeda H. 208 Ikekawa N. 294 Illuminati G. 189 Imuti J.-I. 308 Inaba S. 134 Inaki A. 306 Inbar S. 99 Inch T. D. 138 Ingleson D. 136 Ingold K. U. 53 54 55 62 63 Inoue H. 307 Inoue K. 295 Inoue T. 299 Inouye H. 295 Ippen J. 235 Ireland R. E. 133 187 280 372 Irgolic K. J. 233 Irie K. 85 Irngartinger H. 153 Irving E. 105 Irwin A. J. 297 Ishida H. 188 Ishida M. 239 Ishida T. 132 Ishido Y. 306 Ishii N. 215 Ishikawa H.,223 Ishikawa M. 227 234 Ishikawa N. 120 281 Ishimori M.,124 Ishitobi H. 269 Ishitoku T. 182 Ismail I. M.,10 Isobe M. 242 Isomura K. 70 Isono K.301 Israel R. 191 Itahara T. 215 Itakura K. 310 314 319 Itaya T. 301 Ito K. 206 Ito Y. 131 302 Itoh A. 286 Itoh M. 76 Itoh O. 226 Itsuno S. 126 Ivin K. J. 75 Iwamura H. 69 160 Iwano Y. 234 Iyengar R. 292 Izatt R. M. 167 Izawa Y. 72 75 76 Izumi T. 226 Izumi Y. 206 Jabusch J. R. 352 Jackson A. H. 297 Jackson R. A. 57 58 61 109 Jackson W. P. 145 248 286 Jacques J. 138 Jacquesy J. P. 164 Jacquin D. 90 Jackle H. 337 Jaeger E. 326 329 Jaffe M. L.,356 Jahnke G. 340 Jahr C. E. 343 Jain S. 296 James F. G. 249 James M. N. G. 347 James N. F. 302 James T. L. 5 Jammar R. 181 Jan L. Y. 340 Jan Y. N. 340 Janowski A. 11 Janzen E.G. 54 Jardetzky O. 5 Jardetzky T. S. 5 Jarglis P. 34 Jaun B. 46 Javeri S. 146 Jay E. 314 Jeannin Y.,75 Jefferies P. R. 289 Jellal A. 279 Jemmis E. D. 74 220 Jen K. 117 Jencks W. P. 51 Jenkins E. E. 301 Jenkins J. A. 147 Jenkinson D. H. 332 Jenks W. P. 37 Jenner G. 30 Jensen B. 20 Jensen F. R. 12 62 Jensen J. 74 Jensen R. A. 294 343 Jerina D. M. 176 Jirickny J. 135 321 Jodal M. 339 Jornvall J. 334 Johansen H. 20 Johansen J. T. 352 353 Johansson O. 340 John D. I. 248 John P. 162 Johnson A. W. 59 Johnson B. L. 297 Johnson D. S. 166 Johnson M. D. 58 210 Johnson P. F. 314 Johnson V. 189 Johnston D. B. R. 183 Johnstone R. A. W. 252 273 281 Jones A.J. 296 Jones A. S. 308 320 321 Jones B. N. 344 Jones D. S. 200 Jones D. W. 29 35 Jones G. 68 95 96 Jones M. Jr. 71 73 77 78 227 Jones M. B. 38 70 Jones P. M. 200 Jones P. R. 228 Jones S. S. 318 Jones T. B. 21 153 Jonsson L. 82 Jordan F. 307 Jordan P. M. 8 296 Jouannetoud M.-q. 164 Joubert F. J. 346 JoulliC M. M. 248 Jovanovic B. 39 Jiinemann W.,244 Jug K. 15 17 Julia M. 241 Jund K. 268 Jung G. 325 Jung M. E. 124 Author Index Jungheim L.N. 140 218 237 276 Junglas H. 198 Juri P. N. 167 Jutz C. 160 Kabalka G. W. 270 Kabuto C. 160 Kadir K. 304 Kadokura A. 177 Kahn A. 361 Kai Y.,223 Kaim W. 225 Kaiser C. 181 Kaito M.142 Kaji A. 240 Kaji K. 264 Kakui T. 121 Kalck P. 217 Kaldas M. L. 166 Kalman J. R. 173 Kalyanasundaram S. K. 258 Kametani T. 184 248 Kamounah F. S. 162 Kanagy C. A. 3 Kanakarajan K. 172 175 Kanda K. 15 Kaneko C. 194 Kaneko K. 237 Kanematsu K. 197 Kan-Fan C. 295 Kang S.-K. 176 Kanghae W. 239 Kanno T. 98 Kano S. 112 205 268 Kan-Woon T. 192 Kao G. L. 160 Karanth N. G. 355 Karlsson E.,346 Karnovsky M. L. 351 Karpetsky T. P. 348 KarpIus M. 16 18 Karton Y. 157 Kasai H. 307 Kasai N. 223 Kashimura S. 89 Kasmai H. S. 158 196 Kastin A. J. 344 Kasuga K. 234 Katagiri K. 302 Katagiri N. 197 Katakuse I. 336 Kataoka H. 285 Katayama M. 158 Katayama Y.340 Kates M. R. 42 154 Kato H. 195 Kato K. 129 Kato M. 269 308 Kato S. 25 26 Kato T. 197 216 Kato Y. 273 Katritzky A. R. 39 135 138 168 195 200 Author Index Katsuki T. 124 214 Katsuro Y.,110 214 264 Kattija-Ari M. 154 Katz E. 74 Kaufman J. J. 20 Kaunzinger E. 260 Kaupp G. 95 175 177 Kaura A. C. 184 Kavanagh J. 357 Kawabata N. 139 Kawada K. 178 Kawada Y. 160 Kawagishi T. 274 Kawami Y. 274 Kawamura T. 226 Kawara T. 131 Kawasaki K. 274 Kawasaki T. 302 Kawashima M. 131 Kazansky L. P.,9 Keates C. 68 Keay B. A. 186 Keck G. E. 283 Keinan E. 187 230 282 Keller L. 172 Kellett G. L. 362 Kellog R. M. 190 277 Kellogg M.S. 96 Kelly M. G. 206 Kemal O. 321 Kemister G. 158 Kemp R. G. 362 Kemp T. J. 167 Kempf D. J. 133 277 Kenner G. W. 326 Kennett D. J. 342 Kennewell P. D. 33 Kenyon G. L. 18 308 Kerkmann T. 51 130 Kern D. L. 301 Kerrison S.J. S. 10 Kerschensteiner D. A. 352 Kerwin J. F. Jr. 134 278 Kessel C. R. 186 Khalifa M. H. 325 Khamashesku V. N. 228 Khan J. A. 224 Khan M. N. 340 Khanna V. K. 175 Khatri H. N. 221 Kher A. 176 Khodzhaev G. K. 236 Khorramdel-Vahed M. 162 224 Kibayashi C. 171 Kibby J. J. 298 Kice J. L.,247 256 Kiel W. A. 248 249 257 268 Kikuchi H. 59 Kikukawa K. 167 209 Kilbee G. W. 294 Kim K. S. 23 76 Kim S. J. 188 Kim Y. H. 299 Kimura N.274 Kimura R. 283 Kimura S. 344 King A. J. 103 King A. O. 120 267 King F. D. 272 Kinoshita K. 274 Kira M. 154 229 Kirby A. J. 37 Kirby G. W. 297 Kirby N. V. 189 Kirms M. A. 159 Kise N. 85 Kishimura K. 276 Kita Y. 34 276 Kitagishi J. 336 Kitamura M. 242 Kitamura N. 312 Kitazume T. 281 Kitschke B. 56 68 198 Kladko I. 68 Klarner F.-G. 35 Klapper D. G. 331 Klar G. 260 Klee C. B. 348 349 Kleijn H. 266 Klein G. 29 Klein J. 121 161 Klein P. 246 272 Klein R. S. 303 Kleinschroth J. 161 Kleschick W. A, 129 234 Klima W. L. 120 267 Klingensmith K. A. 159 Klopotek D. L. 70 Klose W. 187 Kluge A. F. 192 Klun T. P. 278 Knack I. 356 Knapp S.277 Knight C. T. G. 9 Knobler C. B. 205 Knof S. 326 Knoll F. M. 36 213 Knolonski E. A. 308 Knorre D. G. 317 Knox S. A. R. 75 Knunyants I. L. 236 KO S. S. 251 Kobayashi H. 303 Kobayashi M. 119 267 Kobayashi Y. 178 285 Kobinata K. 301 Kobuke Y. 308 Kobylinski T. P.,206 Koch C. T. 73 Koch K. H. 70 Kochi J. K. 55 58 59 65 219 231 Kocienski P. J. 234 243 244 273 275 Koeberg-Telder A. 161 Konig H. 242 Korner H. 45 220 Koster H. 316 Koga K. 125 126 Koganty R. R. 194 Kogure T. 206 Kohberger R. C. 355 Kohli V. 306 307 316 Kolar G. F. 174 322 Kolb E. 362 Kolb M. 134 Kollman P. A. 18 197 308 Kolosov M. N. 319 Kolpak F. J. 314 Komatsu K. 44 Komatsu M.234 Komiya Z. 146 Komori T. 302 Komornicki A, 25 Komura H. 307 308 Konar A. 190 Kondo S. 75 Konieczny M. 175 Konig W. A. 301 Kono K. 209 Koob R. D. 57 228 Koppenhoefer B. 124 Koray A. R. 161 Koreeda M. 197 Korolev V. A. 228 Korte F. 177 Kos A. J. 20 220 Kosler H. 306 Kossai R. 181 Koster H. 307 Kosterlitz H. W. 342 343 Kosugi H. 274 Kosugi K. 11 1 224 Kottman N. 308 Koutecky J. 24 KovaE B. 18 Kovacic P. 38 56 70 Kowalewski J. 3 Kowalski C. J. 46 155 Koyama T. 292 Kozikowski A. P. 188,251,279 Kozousek V. 340 Kozuka S. 102 253 Kraeutler B. 103 Kraszewski A. 307 317 Kratt G. 56 Kratzer H. J. 72 Kraus G. A. 31 283 Krause L. J.71 Kraut J. 348 Krebs A. 21 153 Kreher R. 188 Kreil C. L. 228 Kreil G. 346 Kremers W. 54 Krestonosich S. 177 Kresze G. 34 Krief A. 41 109 137 247 248 249 250 252 256 264 266 Kriemler H.-P. 297 Krishnamurthy S. 10 107 138 263 270 Krishnan R. 15 16 17. 25 Kristensen J. 246 Krolikiewicz K. 301 Krooth R. S. 308 Kubo Y. 182 Kubota S. 184 Kudelin A. B. 336 Kuffler S. W. 340 Kuhla D. E. 197 Kulkami A. K. 265 Kulkarni S. U. 113 114 Kulkowit S. 247 Kumada H. 227 Kumada M. 110 121 214 219 264 Kumadaki I. 178 Kumar Y. 168 Kumazawa T. 186 235 Kunitskaya G. P. 261 Kurimoto M. 217 Kurobane I. 294 Kurobe H. 248 Kuroda K. 119 Kurosawa H.226 Kurz J. L. 38 Kuwajima I. 182 252 254 255 269 299 Kwei J. Z. 325 Laali K. 168 Labar D. 247 250 L’abbC G. 180 246 Labrande B. 221 Ladika M. 74 Laganis E. D. 46 143 159 Laguerre M. 171 229 Lai C. 67 174 Lai E. H. 186 Laidig W. D. 17 Laine R. M. 209 210 Laird T. 36 Lakshmikanthan M. V. 189 238 258 Lallemand J.-Y. 5 La Mattina J. L. 193 Lamb J. D. 167 Lambert J. B. 7 43 73 220 Lammertsma K. 44 161 Lampe J. 129 Lancaster J. E. 168 Landen G. L. 281 Landers A. E. 146 Landini D. 113 Lang M. 184 Lang S. A. Jr. 192 Lange F. 154 Lange P. 321 Langlois Y. 295 Lansinger J. M. 219 Lap B. V. 151 164 Lapham D. J. 224 Lapouyade R. 221 Lappert M. F.54 59 226 227 231 Lardy H. A, 361 Larock R. C. 140 207 226 Lasne M.-C. 141 Laszlo P. 4 Lau L. 313 Lau W. 55 Lauer R. F. 233 Laureillard J. 38 Laurent E. 6 Lauterwein J. 337 Lawesson S.-O. 246 Lawrence F. T. 77 Lawrence L. M. 223 Lawrence R. F. 278 Lawrence T. 60 152 284 Lay K. 56 Laycock D. E. 110 Lazarus L. H. 340 LaziC R. 253 Learn K. 204 Lebaud J. 246 Le Blond D. J. 356 Lebowitz P. 312 Ledner J. A. 322 Lee C.-K. 188 Lee D. K. W. 186 Lee H.-C. 125 Lee H. D. 113 Lee H. M. 174 204 Lee J. 38 Lee J. G. 35 Lee S. L. 295 Lee T. W. S. 256 Lee W.-B. 71 Lee Y.-S. 49 Leete E. 295 Leff P. 357 Legon A. C. 200 Lehn J. M. 22 50 199 Lehnig M.53 Lehr F. 271 Lemal D. M. 46 143 159 Lemmer D. 98 Lepoivre J. A. 306 Lesiak K. 308 Leslie A. G. W. 314 Lessard J. 55 Lester D. J. 231 255 256 Letendre L. J. 34 141 Letsinger R. L. 3 17 3 18 32 1 Leuenberger C. 179 Lever J. R. 51 Lever 0.W. Jr. 236 Levisalles J. 75 Levy C. C. 348 Levy H. R. 358 Lewicka S. 70 Lewis G. S.,192 Lewis H. M. 310,313 Author Index Lewis M. E. 341 Lewis N. G. 297 Lewis R. V. 344 Lex J. 147 Ley S. V. 145 185 236 248 255 256 260 261 286 Liakopoulou-Kyriakides M. 337 Lichtenthaler F. W. 34 Liebman J. F. 70 Liedtke R. C. 70 Lien M. H. 21 Lieto J. 209 Liljefors T. 3 Lim M. I. 303 Lim T. F. D. 228 Lin C.-I.97 Lin C.-T. 72 Lin L. C. 195 Lin T.-S. 309 Lin Y.-I. 192 Lind G. 154 Lind R. S. 31 Lindley J. M. 68 Lindner H. J. 22 56 68 198 307 Lines R. 83 93 Ling N. 334 Linkova M. G. 236 Linnoila R. I. 340 Linschitz H. 99 Liotard D. 24 Liotta D. 248 274 Liotta R. 171 Lipisko B. 282 Lipkin D. 302 Lippard S. J. 322 353 Lippert B. 322 Lipscomb W. N. 20 219 Lipshutz B. H. 237 268 Lipton M. F. 219 Lischka H. 21 Lisiak M. 56 Liso G. 135 Lissel M.,119 Little R. D. 273 Liu B. 18 Liu C. 78 Liu J.-M. 96 Liu K.-T. 40 Liu L. K. 117 Liu T. 183 Livett B. G. 340 Ljungdahl A. 340 Lloyd D. 87 Lock C. J. L. 322 Lockhart T. P. 67 Lockley W. J. S.294 Logemann E. 161 Lohrmann R. 320 Lohse C. 194 Lombardo L. 277 Lomitz M. 229 Author Index Long F. A. 164 Loof I. H. 73 Loots M. J. 274 Lopresti R. J. 126 Lord J. A. H. 343 Lorenz B. 67 Lorkerau C. 12 Lottenbach 237 Lottspeich F. 335 Louati A, 86 Lovas F. J. 19 Lowe G. 128 Lown E. M. 76 Lowny L. I. 344 Lu H. S. 334 Lu L. D.-L. 245 Lucchini V. 34 Luche J. 122 Luczak J. 253 Luedtke A. 56 Lui H.-J. 277 Luisi P. L. 337 Lumma P. K. 188 Lunazzi L. 54 Lund H. 83 91 Lundberg J. M. 340 Lundgren O. 339 Lunnon M. W. 294 Lunsford W. B. 317 Lunt E. 135 Lusztyk J. 154 Luxon B. A. 19 Lwowski W. 69 Lysenko Z. 248 Lythgoe B.244 Lytwyn E. 272 Ma E. C. L. 230 Ma P. 283 Maas G. 158 McAlister J. 309 McCandliss R. 310 McCay P. B. 54 McCloskey J. A. 301 McClure D. E. 188 McCombie S. W. 258 McCready R. 124 McCullough J. J. 30 McDonald E. 296 297 McDonald I. A. 298 Macdonald J. E. 251 278 McDonald J. H. 111 127 187 269 MacDonald T. L. 231 285 McDowell D. C. 126 McElligott P. J. 121 Macfarlane R. D. 320 Mcgaugh J. L. 343 McGee L. R. 129 214 269 McGhie J. F. 109 Mach K. 148 213 McIver J. W. 25 Mack A. G. 178 Mackay G. I. 47 McKee M. L. 22 McKenzie A. T. 31 Mackenzie G. 304 Mackenzie I. 339 McKervey M. A. 148,247 McKillop A. 173 McLean A. D. 18 MacLeod I. 289 MacLeod J.K. 23 MacManus J. P. 350 MacMillan J. 293 294 McMillen D. F. 56 McMorris T. C. 234 McMurry J. E. 110 285 McMurry J. M. 264 McNeal C. J. 320 McPhail A. T. 129 McRobbie I. M. 68 Maddex D. 162 Maddox M. 97 192 199 Maeda M. 144 Maeda S. 310 Maeda Y. 62 Maercker A. 221 Markl G. 197 230 Maeshima T. 60 Magaha H. S. 285 Maggiora G. M. 20 26 47 Magid R. M. 37 281 Magnus P. D. 235 236 240 255 Magolda R. L. 248 251 274 Mahatfy P. G. 228 Mahalanabis K. K. 277 Mahalingam S. 231 285 Mahdavi-Damghani Z. 277 Maier G. 21 153 197 228 Maier W. F. 280 Maiolo F. 61 Majchrzak M. W. 220 Majima T. 96 Makani S. 164 Malek F. 61 109 Malhotra R.,137 270 Malinowski D.P. 353 Malleron J. L. 282 Malli G. 17 Mallick I. M. 192 Mallon C. B. 67 Malone J. F. 176 Malsch K.-D. 21 153 Maltsev A. K. 228 Manabe O. 177 Mancilla J. M. 170 Mancuso A. J. 240 Mandai T. 142 Mandal A. K. 113 Mandell L. 89 Mander L. N. 173 277 Mandolini L. 189 Manis P. A. 276 Manitto P. 294 Mann J. 295 Manning W. B. 175 Mansour T. E. 362 Mansuri M. M. 161 Mantei N. 310 Mao M. K. T. 279 Marchand-Brynaert J. 185 Marcuzzi F. 34 Marfat A. 289 Marino J. P. 254 Markham A. F. 319 Markiewicz W. T. 306 Markovskii L. N. 261 Markowitz M. 273 Marquet B. 6 Marschall H. 146 Marsh E. A. 291 Marsh F. J. 18 308 Marshall G. R. 343 Marshall J. A. 139 Marsham P.R. 289 Marsman B. 124 Martens C. 180 Martens J. 233 Martin B. 352 Martin J. C. 55 158 199 Martin M. 295 Martin P. 140 Martin S. F. 241 263 Martinez J. 325 Martinez J. L. 343 Martinez-Dada C. 36 Martini F. 352 Martino P. C. 182 Maruyama K. 119 175 182 215 230 269 282 Marvel] E. N. 34 Marwood J. F. 299 Maryanofi B. E. 76 Marynick D. S. 20 219 Marziano N. C. 164 Marzorati J. 135 Masada G. M. 160 Masaki Y. 264 Masamune S. 139 244 245 269 Mascaretti 0.A. 298 Mascaro L. 298 Maskill H. 44 Maslowsky E. Jr. 219 Masnovi J. 96 Maspero F. 115 Massey V. 348 Masters C. 203 Matcham G. W. J. 296 297 Matharu S. S. 33 Mathiaparanam P. 236 Mathias L.J. 160 Mathre D. J. 187 Mathur N. K. 320 Mathur S. N. 154 Matsubara I. 216 Matsuda A, 210 Matsuda H. 336 Matsuda T. 167 209 Matsumoto H. 8 216 296 30 1 Matsumoto M. 119 Matsumoto T. 19 Matsumura Y. 89 Matsuo A. 293 Matsuo J. 302 Matsuo T. 336 Matsuoka O. 17 Matsuoka Y. 245 Matteson D. S. 113 269 Matteucci M. D. 316 Matthei J. 142 Mattingly P. G. 134 Maux J. L. 311 Mavridis A. 70 Maxam A. M. 3 11 May G. L. 173 May L. 310 Maycock C. D. 184 Mayeda E. A. 83 Mayer B. 77 Mayer R. 233 Mayol L. 313 Mayotte G. J. 84 Mazerolles P. 228 Mazo A. M. 321 Mazur S. 79 Mazzocchi P. H. 3 28 150 Means A R. 348 Medici A. 191 Medlik-Balan A.121 Meek J. L. 333 Meerholz C. A. 260 261 Mehdi S. 308 Mehler E. L. 19 Mehrota A. 124 Meienhofer M. C. 361 Meijer J. 266 Meister J. 71 Meites L. 84 Melchiorri P. 344 Melillo D. G. 183 Melloni G. 34 Mellor J. H. 254 Mellor J. M. 81 86 Melnick B. P. 321 Mel’nikov P. N. 337 Menchen S. M. 11 1 247 248 249 252 257 259 268 Menger F. M. 49 125 153 Menon B. C. 166 Mensink C. 193 Merendi C. 290 Merrien A. 305 Merrienne C. 305 Merrifield R. B. 328 329 Messing R. B. 343 Metcalf B. W. 268 Meth-Cohn O. 68 69 195 197 Metras. R. 39 Meyer N. 169 220 Meyer R. B. 305 Meyer T. J. 92 Meyer W. 17 Meyers A. I. 129 131 193 194 Meyers C. A. 328 333 Michel P.352 Michel U. 157 Michelson A. M. 352 Michl J. 159 Michniewicz J. 316 Middlemiss D. 196 Midland M. M. 126 Mihelich E. D. 131 193 Mihm G. 197 228 Mikhailov S. N. 305 Mikolajczyk M. 137 253 Miles S.J. 226 Millar R. P. 334 Miller A. C. 241 Miller A. L. 173 Miller B. 47 157 Miller J. 166 Miller L. L. 83 85 168 Miller L. S. 39 Miller M. J. 134 241 281 Miller U. S. 295 Millot F. 165 Mills D. J. 163 Milstein C. 312 Mimura T. 235 Minabe M. 177 Minakata H. 274 Minami T. 102 239 Minato T. 74 Mincione E. 266 Mingin M. 28 150 Minkin V. I. 253 261 Minot C. 18 37 Mintmire J. W. 18 Minton M. A. 159 Mioskowski C. 239 289 Miozzari G. 310 Miri A.Y. 162 165 Miroshnikov A. I. 336 Misra R. N. 237 265 Mitchell H. L. 222 Mitchell M. B. 295 Mitchell T. R. B. 140 207 Mitsui K. 175 Mitsui Y. 274 Mitzlaff M. 85 Miura I. 307 Miura M. 99 111 224 Miura T. 41 Miwa T. 72 Miyano S. 115 Miyashita M. 186 235 Miyaura N. 119 Miyazaki Y. 302 Miyazawa T. 301 Miyoshi H. 224 226 260 Miyoshi K. 319 Author Index Miyoshi N. 247 Mizobe F. 340 Mizugai Y. 158 Mizukami H. 295 Mizuno Y. 306 Mizuta T. 99 Mizutani T. 88 Moad G. 62 Mochizuki H. 126 Moder T. I. 12 Modro T. A. 163 Moerck R. 236 Moffat J. B. 220 Mohraz M. 18 Moir M. E. 165 Mojelsky T. W. 65 Molko D. 307 316 Moller M. R. 308 Monteil R.L. 34 Montgomery L. K. 228 Monti D. 294 Moore R. B. 128 Moore S. 326 Moran P. J. S. 166 Morfat A. 264 Morgan B. A. 342 Morgan K. G. 339 Morgan T. A, 197 Mori A. 269 Mori S. 269 Moriarty R. M. 35 Morin C. 306 Morin J. M. 36 Morin L. 246 Morinaga T. 59 Morinaka H. 292 Morisaki M. 294 Morita K. 340 Morita T. 267 Moroder L. 329 Morokuma K. 19 21 24 25 Moro-oka Y. 213 215 Morris H. 58 Morris H. R. 297 335 342 Morris J. 242 Morris J. J. 50 Morris T. M. 170 Morrison H. 95 Morrison J. A. 71 Morrison J. D. 126 Morrison J. F. 359 Morrison M. A, 134 Morton H. E. 229 266 Morton J. A. 145 248 Mortreux A. 210 Moschel R. C. 307 Moshe H. J. 299 Mosnaim A.D. 170 Moss R. A. 49 70 71 73 Mossman A. 41 Motherwell W. B. 61 62 108 231 263 Moubarak L. 186 Movsumzade M. M. 236 Author Index Mowat R. 170 Moxon G. F. 162 Moyce C. D. 308 Moyer B. A. 92 Mpango G. B. 277 Muchowski J. M. 199 Miiller G. 223 Muller K.-H. 181 Mukai T. 73 160 Mukaiyama T. 126 216 245 Mullen G. 242 Muller G. 297 Mullican M. D. 239 Mulvaney M. 273 Mulzer J.. 51 130 Mundy A. P. 294 Munjal R. C. 73 Murad A. F. S. 161 Murad H. H. N. 191 Murahashi S.-I. 122 247 Murai S. 247 Murakami A. 307 Murakami S. 206 Murata K. 210 Murata S. 270 Murphy W. A. 328 Murphy W. S. 169 Murray R. E. 271 Murray R. W. 79 Murray-Rust J.196 Murray-Rust P. 44 196 Murumatsu M. 310 Muscio 0.J. 291 Mushik G. M. 175 Musser A. K. 102 Musumarra G. 39 Muto N. 302 Mutt V. 333 334 Mutter M. 325 Myong S. O. 273 Naddaka V. I. 253 261 Nader B. 31 Nagahara T. 184 Nagai Y. 216 Nagakura N. 295 Nagao Y.,237 Nagase S. 25 Nagata S. 310 Nagata W. 269 Nagendrappa G. 278 Nagira K. 167 209 Naguib Y.M. A. 145 Naidu M. V. 298 Nair M. D. 200 Nair V. 61 131 307 Nair V. G. K. 57 Naish P. J. 75 Naito K. 186 Nakabayashi M. 281 Nakadaira Y.,229 Nakae I. 214 Nakagawa K. I. 227 242 Nakahama S. 126 Nakahara Y. 244 Nakai H. 302 Nakai T. 120 235 Nakaji T. 177 Nakajima N. 195 Nakamichi K. 307 Nakamura A.223 Nakamura S. 348 Nakanishi K. 307 308 Nakasaka T. 305 Nakashima T. T. 7 291 Nakatsuji H. 15 Nakausa R. 55 Nakazaki M. 144 Nakazaki N. 306 Nakazawa S. 176 Nakhdjavan B. 260 Nalewajek D. 189 Nametkin N. S. 228 Nanda D. W. 17 Nanda R. K. 5 Narang C. K. 320 Narang S. A. 313 316 320 Narang S. C. 135 137 164 237 270' Naruse K. 131 Naruta Y. 176 230 269 Naschbar R. B. 292 Nayak D. P. 313 Nayeshiro H. 295 Neckers D. C. 188 Nedelec L. 279 Neef G. 240 Nefedov 0. M. 228 Negishi E. 108 119 120 267 Negoro K. 242 Neier R. 297 Nelson G. O. 72 Nelson J. M. 281 Nelson J. V. 36 245 Nelson N. T. 62 Nelson P. G. 17 Nelson S. D. 197 Nemer M.J. 307 319 321 Nemoto H. 248 Neta P. 102 Neugebauer W. 222 Neukom C. 126 Neumann R. C. Jr. 56 Neumann W. P. 77 230 Newcomb M. 35 134 Newman M. S. 172 175 Newman P. A. 164 Newton C. R.,319 Newton M. D. 19 Newton R. F. 139 140 268 Newton R. P. 308 Ngo T. T. 348 Nguyen T. T. 158 Nguyen Trong Anh 18 37 Nibbering N. M. M. 45 Nice E. C. 333 Nicholas K. M. 267 273 Nickell D. G. 283 Nickels H. 73 Nickischi K. 187 Nickon A. 144 Nicolaou K. C. 241 244 247 248 251 254 269 274 283 Nicoll R. A. 343 Nicotra F. 6 293 294 Nielsen A. T. 171 Nielsen D. E. 194 Niemczura W. P. 309 Nigam A. 124 Nilson J. H. 313 Nimmo I. A. 354 Nishi S. 274 Nishida I. 280 Nishida S.146 189 Nishida T. 275 Nishida Y.,177 Nishikawa J. 302 Nishikawa S. 307 Nishimura S. 205 308 Nishirnura T. 184 Nishio T. 195 Nishitani K. 274 Nishitani Y. 269 Nishizawa M. 247 257 280 Nitasaka T. 58 Noble K.-L. 159 Noda A. 131 Noda S. 99 Noding S. A. 107 Noels A. F. 76 Noest A. J. 45 Noguchi S. 70 Nohara T. 302 Nokami J. 86 Nonhebel D. C. 170 Noodleman L. 19 Noori G. F. M. 168 Nordlander J. E. 6 Nordlov H. 296 Norman J. G. 19 Norman R. 0. C. 55 Normant J. F. 131 271 274 Norris A. R. 165 Norris F. 319 Norris K. E. 319 Norris W. P. 171 North R. A. 340 343 Norton R. S. 4 Notman H. 314 Nowoswiat E. F. 303 Noyori R. 76 270 274 275 280 303 Nozaki H.110 224 243 286 Nozoe S. 129 Nudelman A. 238 Nutter D. E. Jr. 54 Nwokogu G. 67 174 Nymo C. 87 Author Index Oae S. 253 272 Obinata T. 131 O’Boyle J. E. 267 O’Connor T. 308 Odin F. 320 O’Donoghue M. F. 224 O’Donohoe C. 210 O’Dowd M. L. 46 155 Oertle K. 140 224 Ogata Y. 177 Ogawa T. 177 Ogilvie K. K. 136 307 308 317 318 319 321 Ogino K. 102 Ogita T. 302 Oguchi T. 98 Ogura K. 282 292 O’Hare M. J. 333 Ohba N. 256 Ohfune Y. 257 Ohishi J. 139 Ohkata K. 43 Ohki E. 184 Ohmine I. 24 Ohmizu H. 85 Ohno S. 310 Ohnuma Y. 223 Ohsawa A. 178 Ohshiro Y. 234 Ohya-Nishiguchi H. 159 Oida S. 184 Ojima I.134 185 206 Ojima J. 159 Oka K. 130 Okada H. 226 Okamoto K. 44 Okamoto Y. 267 Okamura H. 111 224 Okamura W. H. 70 Okano M. 115 224 226 247 250 254 260 Okawara M. 112 190 241 264 269 Okawara R. 86 Okazaki K. 306 Okhanov V. V. 336 Oki M. 59 Okita M. 85 Okuno H. 75 76 Olah G. A. 7 44 135 137 164 237 270 273 Olbe L. 339 O’Leary M. A. 294 O’Leary M. K. 308 Oliver M. J. 151 Oliver S. A. 220 Ollis W. D. 36 O’Loane J. K. 138 Olsen E. G. 36 Olsen F. 164 Olta K. 200 Omelanczuk J. 137 Omote Y. 179 195 Omura Y. 73 On H. P. 229 Onaka M. 216 245 Onan K. D. 129 Ong B. S. 36 Ong C. W. 145,266 Onishi T. 275 Ono M. 94 254 Oorns P. H. J. 28 150 Opella S.J. 8 Opgenorth H.-J. 244 Oppenhuizen M. 193 Oppolzer W. 33 188 241 265 283 Orere D. M. 135 Orfanopoulos M. 27 28 104 Orgel L. E. 320 Orita Y. 20 Orpen A. G. 75 Ors J. A. 96 Osamura Y. 74 Osawa E. 19 Osborn M. E. 271 Osborne D. A. 58 Osgood E. R. 180 182 Oshima K. 110 224 243 286 Ostah N. A. 77 Otake N. 302 Otsuka H. 296 298 Otsuki T. 175 Oudenes J. 274 Ourisson G. 293 Ovchinnikov Yu A, 336 Overballe-Petersen C. 352 Overberger C. G. 160 Overill R. E. 54 Overman L. E. 36 213 271 Overton K. H. 289 Owada H. 115 250 Oxman J. D. 98 Ozawa S. 286 Paaren H. E. 35 Pac C. 96 Pacala L. A. 73 Pachlatko J. P. 292 Packer K. J. 8 Paddon-Row M.N. 18 151 164 Padwa A. 35 195 Padynkova N. S. 306 Pagano A. S. 171 Page M. I. 50 Pai Y. 78 Paik H.-N. 246 Pais M. S. S. 302 Palese P. 313 Palm J. 147 Pandy-Szekeres D. 238 Panem S.,310 Panetta C. A. 173 174 Pang F. 18 Pant C. M. 184 Pantoliano M. W. 353 Panunzi A. 212 Paolucci C. 144 Papies O. 32 Papoula M. T. B. 231 Paquer D. 246 PBques E. P. 338 Paquette L. A, 28 29 31 36 43 72 140 147 242 271 284 Paquin D. P. 230 Paradies H. H. 360 Pardo S. N. 33 116 278 Parker K. A. 176 Parker V. D. 80 81 83 93 Parry K. P. 293 Parry R. J. 296 298 Parshall G. W. 203 Parsons I. W. 178 Parsons P. J. 235 266 Pascal R. A. 293 Paske D. 147 Passlack M.221 Pasto D. J. 30 Patel N. J. 294 Patel R. C. 135 168 Patel T. P. 310 313 Paterson I. 235 Paterson S. J. 343 Patney H. K. 152 164 Patrick D. W. 233 Patrie W. J. 123 Patterson W. 120 267 Paul H. 57 Paul M. A. 164 Pauling L. 23 70 Paupart M. A. 132 Pauson P. L. 140 hvelka L. A. 299 Payne D. R. 167 Pearce C. J. 298 Pearce F. L. 332 341 Pearce H. L. 268 Pearlman B. A. 101 Pearson A. J. 145 266 284 Pearson N. R. 113 Pearson R. G. 38 Pearson R. L. 164 Peattie D. A. 322 Peck C. J. 143 Pedersen B. S. 246 Pedulli G. F. 60 Pegram J. J. 268 Pegues J. F. 271 Pelech B. 32 Pelerin G. 284 Pelister M. Y. 178 Pellacani L. 70 Pellerite M. J. 37 Peoples P.R. 45 154 Pereyre M. 230 Perina I. 253 254 Perkins C. W. 55 Perkins K.A. 77 Author Index Perkins M. J. 55 249 Perkins P. G. 77 Pomeroy R. K. 9 Pon R. T. 318 Quigley G. J. 314 Quinn R. J. 4 299 Perlikowska W. 137 Ponder J. W. 273 Quintard J. P. 230 Pernow B. 340 Ponec R. 158 Quinterio M. 196 Persia F. 70 Pons A. 152 Pestka S. 310 Peters D. 19 Peters D. G. 146 Peters J.. 19 Peters K. 180 Peterson D. 132 265 Pons B. S. 81 Ponsford R. J. 184 Ponti F. 187 Ponticello G. S. 188 Pontikis R. 305 Poole I. 292 Raap B. 231 Raasch M. S. 189 Rabinovitz M. 159 Radhakrishna A. S. 192 Radley P. 68 Radom L. 18 23 157 158 Peterson G. L. 348 Petiniot N. 76 Pettit F. 210 Petke J. D. 20 Petro C. 42 Petrongolo C. 20 Petrzilka M. 250 Petit G. R. 307 Petty S.R. 192 Pez G. P. 204 Poonian M. S. 303 Pople J. A. 15 16 17 23 Popov E. M. 337 Popov S. G. 314 317 Poppinger D. 20 Poquet E. 24 Porta O. 249 Porter A. G. 310 Porter J. W. 294 25 Rafalko J. J. 18 Raghavan N. V. 161 Ragnarsson U. 337 Rahm A, 230 Rahman K.-U.,166 Raithby P. R. 266 Rajagopalan K. V. 357 Rajappa S. 200 Ramachandran K. L. 326 220 Pfenninger J. 263 Pfitzner A, 295 Pfleiderer W. 3 17 Porter K. 314 Porter Q. N. 237 Post R. M. 342 Ramage R. 326 Ramasamy K. 258 Ramasubbu A. 140 207 Pfoertner K.-H. 181 Potenza D. 291 Ramsden C. A. 197 Pfund R. A. 49 Phillippi M. A. 11 Potier P. 295 Potter B. V. L. 128 Ramsey J. N. 163 Randerath E. 312 Phillips G. W. 241 Potter G. F. 140 Randerath K. 312 Phillips P. 17 Phillips R. B. 35 Phinney B. O. 293 Piatik M. 312 Piau F.281 Potuin B. W. 308 Poulos T. L. 348 Poulter C. D. 291 Poutsma M. L. 63 Pover K. A. 120 Ranghino G. 20 Ranson R. J. 162 224 Ranzi B. M. 6 293 Rao A. S. C. P.,244 Rao C. G. 114 Picard J.-P. 238 Power J. L. 54 Rao 0. S. 69 Pienta N. 42 Piepers O. 277 Pierce R. A. 228 Pierdet A. 279 Piers E. 229 266 Pike S. 272 Pillai V. N. R. 268 Pillot J.-P. 238 Pinder A. R. 138 263 Power P. P. 54 Power P. R. 231 Pradayrol L. 329 334 Praefcke K. 91 233 Prakash G. K. S. 44 237 Prasad K.,184 Price R. 4 211 Prince T. L. 109 273 Rappoport Z. 49 Rastall M. H. 145 Rasteikiene L. 236 Ratcliffe R. W. 183 Rathke M. W. 276 Ratliff R. L. 314 Rattan S. 339 Raucher S. 246 251 272 278 Pine S.H. 211 Pinhey J. T. 173 Pinson J. 80 Piomelli S. 361 Piper P. J. 335 Pirkle W. H. 123 191 Pirrung M. C. 128 129 Pittman C.U. 210 Pitzer K. S. 17 Placucci G. 54 Plambeck J. A. 65 Platen M. 237 Pletcher D. 90 93 Plomp R. 90 Pluth J. J. 205 Pocklington J. 21 153 Poehler T. O. 189 Poje M. 253 Polak V. 253 Pollicino S. 144 199 Polverelli M. 320 269 Prinzbach H. 181 Prisbylla M. 282 Proehl G. S. 95 146 Prokopiou P. A. 109 Pross A. 18 157 158 220 Prudent N. 128 Prusoff W. H. 309 Pryde L. M. 8 296 Pryor W. A. 57 Puget K. 352 Puglia G. 169 Pulay P. 18 24 Pullman A. 20 Purrington S. T. 51 Pyne S. G. 31 Pyper N. C. 17 Quast H. 180 Quesneau-Thierry A. 297 Quici S. 124 Ravanal L. 168 Rawdah T. N. 7 44 Ray N. K. 25 Ray R. 113 269 Raykova D. 358 Rayner B. 318 Razaq M. 90 Read R. W. 170 258 259 Rebek J. Jr. 124 Redding T. W. 328 334 Reddy V. B. 312 Redfearn J. 331 Reed D. W. 65 Rees C. W. 69 Rees D. C.145 266 Reese C. B. 135 304 314 Reetz M. T. 109 263 280 Regan M. 3 Regen S. L. 124 Reger D. L. 112 121 316 318 321 379 380 Author Index Rehfeld J. 340 Rehling H. 85 Reich H.J. 233 247 249 250,252 Reichel C. J. 135 Reid S. T. 189 Reinhart G. D. 361 Reisenauer H. P. 68 197 198 228 Reisfeld A. 313 Reissig H.-O. 139 276 277 Relles H. M. 166 Remaut E. 310 Renfrow R. A. 165 Renneboog R. M. 145 242 Rentzepis P. M. 100 Retta M. 224 Rettrup S.,20 Reutrakul V. 239 Revankar G. R. 305 Revelle L. K. 182 Reynolds W. F. 78 158 Reynolds-Warnhoff P. 47 Rhouati S. 69 Ribeiro A. 5 Ribet A. 329 334 Ricca G. S. 290 Ricciardi F. 248 Rich A. 314 Richardson S. G. 61 307 Richman J.E.,189 Richman P. G. 348 Richter W. 225 Richtsmeier S. 219 Rickards R. W. 298 Rickborn B. 186 Ridd J. H. 163 Riddell F. G. 200 Ried W. 166 Riegler N. 153 Rieker A. 325 Rife J. E.,358 Rigaudy J. 272 Riggs N. V. 18 Righini A. 241 Rigter H. 343 Riley C. M. 271 Riley P. I. 54 227 Rilling H. C. 291 Rimmelin J. 30 Rinaldi P. L. 123 Rinehart K. L. 298 Ringshandl R. 147 Rip~ll,J.-L. 141 Riquelme P. T. 362 Ritchie C. D. 157 Rivers G. T. 269 Rivibre H. 273 Rivibre P. 54 227 230 Riviere-Baudet M. 54 227 Robbiani C. 33 265 Robbins J. D. 95 Roberge R. 57 228 Robert J. B. 5 Roberts B. P. 53 55 62 Roberts D. 362 Roberts D. A. 241 283 Roberts E.F. 180 Roberts J. D. 9 298 Roberts R. M. G. 162 224 226 Roberts S.M. 139 Robins D. J. 251. 295 297 Robins R. K. 305 Robinson S. R. 165 Roch B. S. 77 Rodbard D. 356 Rodini D. J. 32 115 116 265 285 Rodrigo R. 186 Roe B. A. 311 Rosch L. 229 Roessler F. 229 Rottele H. 199 Rogers H. R. 222 Rogers R. J. 222 Rogers W. O. 308 Rogerson C. V. 35 Roget A. 307 316 Rohm K.-H. 356 Rohmer M. 293 Rolla F. 113 Rommer W. 322 Rona R. J. 132 Ronald R. C. 219 Ronchetti F. 6 293 294 Rondan N. G. 22 28 71 150 Rooney J. J. 75 148 210 Roos B. O. 17 Rose M. E. 281 Rosen B. I. 220 Rosenblum M. 216 Rosenfeld M. N. 255 Rosenthal A. 305 Rosmus D. 228 Ross D.S.,163 Ross M. J. 310 Rossa L. 241 Rossi T. 292 Rosier J. 344 Roth B. 21 Rothschild J. M. 298 Rotilio G. 352 Rottman F. 313 Roundhill D. M. 209 Roush D. M. 32 115 265 284 Rowan M. G. 292 Rowan R. 3 Rozeboom M. D. 22 28 150 Rubin C. M. 321 Rubin J. R. 348 Rubinow D. R. 342 Rudesiler P. F. 10 Rudler H. 75 Rudnick D. 197 230 Riichardt C. 56 168 Ruediger E. H.. 166 Rueffer M. 295 Rufalska M. 303 Ruge B.,.103 Rumjanek F. D. 332 Rummel S. 67 Runge T. A. 140 218 276 Russell C. G. 248 249 257 268 Russell G. A. 224 Russo,G. 6 293 294 Ruston S. 244 Ruther F. 34 Ruzziconi R. 51 Ryan K. 183 Ryan P.B. 19 Ryang H.-S.,105 Rylander P.203 Rzepa H. S. 18 Saadein M. R. 196 Sabesan S. I. 277 Sabin J. R. 18 Sabourault B. 128 Sacks C. E. 234 Sadd E. F. 162 Sadekov I. D. 261 Sadler A. C. 219 Sadler P. J. 10 SadIowski J. E. 157 Saegusa T. 274 Safa K. D. 228 Safarik I. 57 228 Said S. I. 339 Saidi K. 140 Saindane M. 274 St. Amour T. 9 Saito A. 292 Saito K. 73 Saito T. 305 Sakaguchi R. 256 Sakairi N. 306 Sakaki S. 253 Sakamoto M. 179 Sakamura S. 283 Sakata J. 280 Sakdarat S. 251 Sakizadeh K. 39 Sakuma K. 264 Sakurai H. 54 96 98 154 229 267 277 Salem G. F. 237 Salisova M. 216 Salomon M. F. 33 116 278 Salomon R. G. 33 116 278 Salzmann T. N. 183 Saman E. 310 Samek Z. 306 Sammes P.G. 33 Samuelsson B. 289 Sancassan F. 152 Sancovich H. A. 297 Author Index Sandel B. B. 158 Sanders J. K. M. 3 Sanders M. E. 273 Sandin R. B. 175 Sandmeier D. 277 Sando K. M. 157 Sandor C. 228 Sandorfy C. 57 Sandri E. 144 199 Sanechika Y. 302 Saneyoshi M. 308 Sanger F. 311 Sano H. 112 190 264 Santaniello E. 187 Santelli M. 279 Santiago C. 18 22 Santiago M. L. 238 Sarah F. Y. 293 Sartori G. 169 Saruwatari M. 70 Sasaki T. 189 Sasakura K. 170 Sasavage N. L. 313 Satgt J. 77 230 Sathe G. 314 Sato F. 223 Sato M. 223 Sato R. I. 175 Sato T. 131 303 Sato Y. 129 Satoh H. 269 Satoh T. 256 Satterthwait A. C. 48 Saucy G.126 Sauer J. 30 147 Saunders M. 23 42 152 154 Saunders W. D. 143 Sauter H. 140 Saveant J. M. 79 80 Savoia D. 109 136 Savva R. A. 224 Sawai H. 320 Sawaki S.,237 Saxe P. 17 21 24 Say B. J. 8 Scaiano J. C. 53 63 99 102 Scamehorn R. G. 167 Scanlon D. 319 Scarafile C. 185 Scarborough R. M. Jr. 247 254 Scarpulla R. 313 Schaal R. 168 Schaart B. J. 223 Schade G. 285 Schaefer H. F. 111 17 21 23 24 25 70 76 77 Schafer H. J. 85 112 Schaefer L. 18 19 Schaffalitzky de Muckadell 0. B. 339 Schaffner K. 98 Schally A. V. 328 334 344 Scharf R. 326 Scharfenberg. P. 16 Schaumann E. 181 Schefer P. 180 Scheffer J. R. 95 101 Scheffers-Sap M. M. E. 308 Scheffold R.141 277 Scheibye S. 246 Scheiner S. 19 Scheinmann F. 120 Scherer B. 277 Scherrer R. A. 170 Scheuer P. J. 130 Scheuermann H. 244 Schiavi P. 352 Schill G. 161 Schilling W. 244 Schinina M. E. 352 Schipper D. 298 Schlegel H. B. 15 17 25 Schleyer P. von R. 20 21 23 24 45 219 220 222 Schlosser M. 222 Schlueter R. J. 331 Schmalz P. F. 339 Schmalzl P. W. 83 Schrnelzer A. 18 21 153 Schmickler H. 198 Schmid C. W. 321 Schrnid G. 140 277 285 Schmidbaur H. 223 Schmidt A. H. 138 Schmidt G. 279 Schmidt M. 126 Schmidt S. P. 98 Schmidt U. 124 Schmidt W. 174 Schmiesing R. J. 25 1 Schmitt D. 188 Schmitt S. M. 183 Schmitthenner H. F. 241 283 Schmitz L. R. 43 154 Schmuff N.R. 241 281 Schneider D. R. 154 Schneider J. A. 127 269 Schneider K.-A. 153 Schneider M. M. 296 Schold M. 314 Schoeller W. W. 23 70 71 220 Schollkopf U. 236 Scholze H. 338 Schorkhuber W. 305 Schowen R.L. 26 47 Schreiber R. 24 55 74 Schreier P. H. 311 Schriever M. 77 230 Schroder G. 199 Schroder M. 113 269 Schroepfer G. J. 293 Schultz A. G. 192 Schultzberg M. 340 Schurig V. 124 Schuster D. I. 103 Schuster G. B. 73 Schwartz A. 254 Schwartz J. 225 266 274 Schwarz B. 306 Schwarz H. 23 Schwarz J. 46 Schwarzstein M. 310 Schweizer B. 221 Schweizer M. P. 305 Schweizer W. B. 49 Schwietzer J. 343 Schwindeman J. 236 Scolastico C. 290 291 Scott A.I. 8 295 296 297 Scott L. T. 22 74 159 Scott W. J. 110 264 Scullion I. 170 Seaman C. 361 Sebastiani G. V. 51 Sedmera P. 148 213 Seebach D. 48 126 169 220 221 236 268 270 271 Seeburg P. H. 310 Seeger A. 240 Seeger R. 16 Seehra J. S. 296 Sefton M. A. 297 Segal G. A. 18 Segaud C. 57 Segawa J. 276 Segre A. L. 157 Seguin R. P. 138 Sei T. 223 Seidel W. 85 Seidov M. A. 236 Seiler P. 221 Seitz D. E. 265 Seitz S. P. 247 248 Seki S. 59 Sekine M. 305 307 316 Selby K. 58 Self R. 302 Seligman A. M. 174 Sell C. S. 64 Sell G. 166 Sellars P. J. 64 Sellers H. L. 18 19 Sellner I. 147 Seltzer H. 177 Sernmelhack M. F. 145 172 212 Semple J.E. 248 Senda S. 195 Senyavina L. B. 336 Seo S. 294 Seoane C. 196 Serdijn J. 316 Serelis A. K. 53 60 152 284 Sergeev G. B. 222 Servis K. L. 154 Servy C. 297 382 Seto S. 292 Seufert W. 172 Sevrin M. 41 109 137 249 252 Sexton M. D. 55 Seyferth D. 227 Seymour C. A. 28 192 Sha C.-K. 192 Shabana R. 246 Shah S. K. 252 Shamouilian S. 174 Shanmugam P. 258 Shantz B. S. 186 Shanzer A. 123 Shapiro R. 321 Shapiro R. H. 219 Sharief F. 348 Sharma A. K. 36 140 Sharma S. 233 Sharmouilian S. 67 Sharpless K. B. 124 214 233 247 257 Shaw G. 200 304 Shaw R. A. 10 Shaw T. J. 124 Shea K. J. 31 35 Shearouse S. A. 220 Sheehan J. C. 177 Sheikh Y.M. 175 Sheldrick G. 30 Sheng S. J. 63 Shenvi A. B. 132 Sheppard R. C. 319 330 Sheu C.-F. 40 Shevlin P. B. 73 182 Shiau G. T. 309 Shiba K. 194 Shibib S. M. 277 Shibuya M. 184 Shikita M. 294 Shimazaki N. 160 Shimidzu T. 307 Shimizu H. 131 182 252 254 255 Shimonishi Y. 336 Shinkai I. 183 Shinkai S. 177 Shinozaki H. 125 Shiobara Y. 295 Shioiri T. 277 Shiota M. 205 Shipman L. S. 20 Shipolini R. A. 332 Shirahama H. 19 Shiro M. 302 Shiroishi Y. 159 Shishibori T. 292 293 Shively J. E. 344 Shoma A. 310 Shono K. 216 Shono T. 85 88 89 Shosenji H. 163 Shrere D. S. 358 Shroyer A. L. W. 12 Shue F.-F. 154 Shur V. B. 67 Shvo Y. 210 Sichert H.147 Siefert E. E. 62 Siegbahn P. E. M. 17 Siege] H. 203 Siehl H.-U. 154 Sieloff R. F. 146 Sievers R. E. 157 Silveira A. Jr. 120 191 267 Simmons R. G. 226 Simonet J. 181 Simpson T. J. 291 294 Sims C. L. 245 Sinclair J. A, 207 Singer S. P. 233 Singh A. 54 226 248 249 257 268 Singh A. N. 296 Singh H. 57 Singh K. 62 Singh M. 314 319 Singh P. 67 97 Sinhababu A. K. 131 Sipio W. J. 248 274 Sherman F. 313 Sitzmann M. E. 171 Skalka A. M. 313 Skirboll L. 340 Skoda J. 306 Skogland U. 348 Slade J. 129 194 Slade J. S. 274 Sladkov A. M. 120 Sladky F. 10 Sleevi M. C. 106 190 Sletzinger M. 183 Sliwa W. 194 Small R. D. 99 Smallberg S. A. 342 Smirnov V.V. 222 Smit C. J. 90 Smith A. B. 111 247 254 274 Smith A. J. H. 311 Smith B. V. 249 Smith C. L. 71 Smith D. J. H. 7 136 308 317 Smith D. N. 9 Smith G. P. 161 Smith J. C. 310 Smith J. D. 224 Smith J. G. 186 Smith K. 194 Smith M. 313 Smith R. A. J. 89 237 Smith T. W. 342 Smrt J. 306 Snider B. B. 32 115 116 265 285 Snieckus V. 277 Snitman D. L. 269 Author Index Snyder J. P. 35 36 Snyder S. H. 343 SO,Y.-H. 168 Sochaki M.,308 Sohn J. E. 129 Solladie G. 238 239 Solouki B. 228 Sombroek J. 147 Sondengam B. L. 121 264 Sondheimer F. 68 159 Sonnet P. E. 111 265 Sonoda N. 247 Sood G. R. 298 300 Sorensen C. M. 219 Sorensen T. S. 43 154 Sorgi K.L. 251 Sorkhabi H. A. 165 Soto J. L. 196 Soucy D. 199 Soulie J. 5 Southgate R. 184 Spanget-Larsen J. 29 Spangler D. 19 26 47 Sparapani C. 162 Spencer A. 209 Spencer H. K. 257 258 Speranza M. 157 162 Spielvogel B. F. 129 Spindell D. 32 115 265 Spiro T. G. 18 Spliethoff B. 206 Spry D. O. 184 Spurgeon S. L. 294 Squillacote M. 298 Sreekumar C. 220 269 Sridharan S. 157 Srinivasan R. 96 Srivastava A. K. 355 Staab H. A. 160 Stabinsky Y. 316 Staden R. 311 Stahle M. 222 Stahl D. 23 Stahly B. 28 150 Staley S. W. 154 Stang P. J. 74 158 160 Stanley J. 312 Stanssens P. 310 Stark T. J. 62 Staunton J. 289 290 Stawinski J. 307 317 Stebbing N. 310 Stec W.J. 308 Steckhan E. 93 237 Steele K. P. 77 220 227 Steenken S. 161 Stegelmeier H. 198 Stegman H. B. 53 Stein S. 344 Stein S. E. 55 Steinbach R. 263 Steinman H. M. 352 Steliou K. 132 Stephan W. 109 Author Index Stephenson L. M. 27 28 104 Stern A. S. 344 Stern H. J. 308 Stern P. 253 Sternbach D. D. 296 Sternberg E. D. 145 Sternhell S. 173 Stevens R. V. 273 Stevenson G. R. 159 Stewart A. G. 310 Stewart M. J. 210 Stewart R. F. 16 85 Steyn P. S. 291 Stilbs P. 3 Stiles J. I. 313 Still W. C. 127 187 220 251 269 270 Stille J. K. 208 213 230 279 Stobie A. 299 300 303 Stockigt J. 295 Stoessl A. 292 Stone A. J. 26 Stoodley R. J.184 Storace L. 180 182 Stork G. 244 Stothers J. B. 292 Stott P. E. 199 Straetmans U. 67 Straughn J. L. 295 Strauss M. J. 165 Strausz 0.P. 57 75 76 228 Stray A. C. 167 Streitwieser A. Jr.. 16 219 Streuli M. 310 Stringer M. B. 186 Stringham R. A. 58 Stronks H. J. 54 Stuhl O. 219 Stukalo E. A. 261 Su B. M. 222 Su S. 234 Suchanek G. 346 Sudha B. P. 209 SGehiro T. 55 Suemitsu R. 217 273 Suenram R. D. 19 Suga S. 185 Suga T. 292 293 Sugasawa T. 170 Sugawara T. 69 Sugihara H. 240 Sugino E. 205 Sugiyama H. 54 Sugiyama I. 195 Suhr R. G. 173 Sukumaran K. B. 255 Summers R. 342 Sundaralingam M. 309 Sung W. L. 313 316 Surya G. K. 135 Suschitzky H.68 178 Sustmann R. 30 154 Sutherland J. K. 139 Sutherland I. O. 18 36 Sutton R. W. 220 Suzuki A, 111 119 276 Suzuki H. 213 215 Suzuki J. 205 Suzuki K. 126 177 248 Suzuki M. 270 274 275 348 Suzuki N. 17 Suzuki S. 72 132 Suzuki T. 274 Suzuki Y.,184 Svendsen I. 352 Svoboda M. E. 331 Swain C. S. 167 Swaminathan P. 309 Swanson B. I. 18 Sweeney J. R. 298 Swern D. 240 Szczygielska-Nowosielska A. 132 Sziligyi I. 63 Szirovicza I. 63 Szmant H. H. 11 Szostak J. W. 313 Szurszewski J. H. 339 Szymoniak J. 33 Taber T. R. 234 Tabony J. 5 Tabor J. M. 310 Tabushi I. 308 Tachibana S. 344 Taft R. W. 158 Tagawa H. 34 Tagliaferri E. 68 198 Tagliavini E.109 136 Tai A. 206 Taieb M. C. 5 Takacs J. M. 128 Takahashi A. 306 Takahashi I. 205 Takahashi M. 121 208 Takahashi T. 121 208 234 285 Takai K. 110 224 243 Takaki K. 242 Takaku H. 308 Takano T. 314 Takao S. 293 Takayama K. 183 Takeda N. 184 Takeda R. 254 255 Takei H. 111 224 Takeichi T. 124 Takemura K. H. 186 Takeno H. 185 Takio K. 348 Takita S. 256 Talaty E. R. 180 Talbiersky J. 124 Talekar R. R. 297 Talent J. M. 334 Taljaard N. 346 Talley J. J. 40 Tam T. F. 131 265 Tamblyn W. H. 59 Tamagaki S. 105 253 Tamao K. 121 214 Tamura N. 256 Tamura Y.,34 276 Tanaka K. 26 76 Tanaka S. 314 Tanaka Y.,112 205 268 312 Tang Y.-N., 62 Tanigawa Y.,122 Taniguchi H.70 Taniguchi T. 310 Tanikaga R. 240 Tanimoto M. 139 Tanner D. D. 59 65 Tanner S. D. 47 Tanner S. F. 8 Tanno N. 126 Tardella P. A. 70 Tarnowski B. 195 197 Taschner M. J. 31 283 Tashiro T. 55 Tatemoto K.,333 Tatewaki H. 16 Tatlow J. C. 178 Taussig R. 313 Tavernier J. 310 Tavouktsoglou A. N. 16 Tawara K. 274 Taylor E. C. 173 Taylor G. E. 75 Taylor G. N. 177 Taylor G. W. 335 Taylor H. M. 173 Taylor J. B. 33 Taylor K. F. 23 Taylor K. M. 299 Taylor N. J. 226 Taylor P. R. 17 Taylor R. 162 163 Taylor R. G. 140 Taylor R. J. K. 268 Tedder J. M. 57 59 115 Teisseire P. 284 TejEka M. 351 Telford R. P. 273 Temple J. S. 266 Teoule M.320 Teoule R. 307 316 Terashima S, 125 126 Terenghi G. 169 Terrier F. 165 Terwilliger T. C. 338 Testaferri L. 61 Teuerstein A. 67 174 Teufel E. 175 Teyssie P. 76 Thaisrivongs S. 187 Thakur A. K. 356 Author Index Thamm P. 326 Thetaz C. 68 198 Thibblin A. 52 Thiebault A. 80 Thiel W. 17 20 Thies H. 23 Thijs L. 75 Thind S. S. 135 Thomalla M. 6 Thomas D. W. 209 Thomas E. J. 248 Thomas J. K. 103 Thompson J. C. 78 Thompson J. T. 44 Thompson M. 297 Thompson M. S. 92 Thomson P. C. P. 68 Thorne C. J. R. 347 Thorp G. A. 285 Thorpe W. D. 326 Thummel R. P. 139 Tiecco M. 53 61 Tietze L.-F. 30 Tiffeneau M. 169 Timberlake J. W. 56 Timmins G. 52 Tingoli M.61 Tippins J. R. 335 Tipton K. F. 347 354 Tishbee A. 130 Titmas R. C. 314 Tobias R. S.,308 Tobita H. 229 Tocik Z. 306 Toda T. 160 Toder B. H. 247 Toeplitz B. 236 Totsch W. 10 Toia R. F. 289 Tokach S. K. 57 228 Toki T. 176 Tokumaru K. 98 Tokunaga H. 33 Tolle J. C. 325 Toma L. 6 293 294 Tomaszewski J. E. 175 Tomioka H. 72 75 76 Tomioke I. 44 Tomisawa H. 195 Tomita Y. 294 Tomizawa K. 177 Tomo Y. 132 Topol A. 49 Toppet S. 180 Tori K. 294 302 Torii S. 94 243 244 254 Toromanoff E. 139 Torres M. 75 76 Tortorelli V. J. 77 78 227 Toshimitsu A. 115 226 247 250 254 Totino F. 191 Touillaux R. 181 Townsend L. B. 305 Townson M. 57 Toyne K. J. 108 109 Toyoda T. 170 Trainor D.A. 298 Tramontano. A. 126 Tranquilla T. 314 Traverso P. G. 164 Tremelling M. J. 167 Trend J. E. 247 250 Trenwith A. B. 55 Trevan M. D. 348 Trevor P. L. 56 Tribe D. E. 296 Trinquier G. 77 Trombini C. 109 136 Trost B. M. 117 132 140 142 144 187 203 217 218 230 233 234 235 237 238 241 243 244 266 269 276 278 279 281 282 286 Trotter J. 101 Trujillo J. L. 361 Tsai L. 234 Tsai M.-D. 289 Tse Y.-C. 19 Tsoungas P. G. 194 Tsuchihashi G. 282 Tsuda T. 274 Tsui F. 338 Tsuji J. 121 142 203 208 234 285 Tsuji N. 205 Tsuji T. 146 269 Tsujino M. 302 Tsumoda T. 270 Tsuruta T. 124 Tsuzuki K. 278 Tu C.-P.D. 321 Tucker J. N. 11 Tucker J. R. 74 Tuis M. A. 273 Tukada H. 160 Tuli D.281 Turecek F. 148 213 Turkenburg L. A. M. 146 160 Turner E. S.,55 Turner J. 194 Turrell A. G. 173 Turro N. J. 73 96 103 Tuttle R. C. 293 Tye B.-K. 313 Tzeng D. 77 227 Tzschach A. 231 Ubasawa A. 316 318 Ubasawa M. 318 Udenfriend S. 344 Ueda T. 307 Uemura S. 115 224 226 247 250 254 259 260 Ueno Y. 112 190 241 264 269 Ugi I. 325 Uhlig E. 203 Uhlman E. 317 Ullman E. F. 97 Ullrich A. 310 Ulrich J. 320 Ulrich P. 273 Ulrich S. E. 298 Umani-Ronchi A. 109 136 Umeda Y. 115 Umezawa B. 237 Umino H. 54 Uneyama K. 94 243 244 254 Unger P. L. 173 Uramoto M. 301 Ushay H. M. 322 Usher J. J. 297 Usui Y.,88 Utley J. H. P. 83 88 237 Uyeda K. 360 Uyeo S. 269 Valavoine G. 276 Valente L.F. 119 267 Valentine B. 9 Valentine J. S. 353 Valle G. 212 Vanaman T. C. 348 van Boom,J. H. 314 316 van de Griendt F. 161 Van den Enden L. 18 van den Eynde I. 230 van der Baan J. L. 298 van der Marel G. 34 Van Derveer D. 128 146 175 269 van Deursen P. H. 316 Van Ende D. 249 van Gunsteren W. F. 16 Van Hemelrijk D. 18 Vanhove D. 210 Vankar Y. D. 237 273 van Lente M. A. 170 van Leusen A. M. 140 193 van Leusen D. 140 Van Meerssche M. 181 246 van Nispen J. W. 327 328 van Nispen S. P. J. M. 193 van Noort P. C. M. 100 van Riel H. C. H. A. 95 van Straten J. 285 van Straten J. W. 146 160 van Tamelen E. E. 293,317 van Tilborg W. J. M. 90 Van Wyck J. J. 331 Varley J. H. 252 Varshney A.318 Vasquez B. J. 343 Vassilenko S. 312 Vasudeva Murthy A. R. 10 Vaultier M. 238 Vaya J. 182 Author Index Vaysse N. 329 Vedejs E. 196 Vederas J. C. 7 Veliquette J. 343 Venayak N. D. 68 Venkataraman K. 132 280 Vennos A. N. 11 Venturoli C. 191 Verderos J. C. 291 Verhoeven J. W. 139 Verhoeven T. R. 132 243 281 Verkruijsse H. D. 120 Vermeer P. 266 Vernon C. A. 332 334 341 Verpeaux J.-N. 241 Vessiere R. 186 Vetter W. 161 Vicens J. J. 46 Vick S. C. 227 Vidal J. L. 209 Vierling P. 199 Vieta R. S. 35 Vigneron J. P. 126 Vijaya S. 18 Villain G. 217 Villemin D. 61 108 263 Vincent C. A. 87 Vincent J. E. 142 244 286 Vining L. C. 294 Viola A. 33 Viola R. E. 359 Viriot-Villaume M.-L.100 Visser C. P. 161 Visser R. G. 268 Vitagliano A. 212 Vitullo V. P. 157 Vladuchick W. C. 235 Vleggaar R. 291 296 Vogtle F. 160 161 199 241 Vogel E. 147 159 198 245 Vogler E. A. 59 Volckaert G. 310 Volkova V. V. 228 Vollhardt K. P. C. 30 139 145 207 283 Vol’pin M. E. 67 von Kiedrowski G. 30 von Puttkamer H. 147 von Schering H. G. 180 Vora S. 361 Vorbruggen H. 301 Voyle M. 211 Wada A. 216 Wada F. 167 209 Wada K. 132 159 Waddington D. J. 58 Wade P.A, 242 Wadsworth H. 294 Wagenknecht J. H. 89 Wagle D. R. 132 280 Wagner A. 147 Wagner G. J. 95 Wagner R. D. 60 Wahren M. 67 Waight R. D. 357 Waisman D. M. 348 Wakabayashi S. 86 Wakamatu T. 85 Wakasugi M. 226 260 Wakefield B.J. 178 Wakita Y.,197 Walba D. M. 186 Walde P. 337 Walder L. 141 Waley S. G. 355 Walker G. 23 Walker J. E. 352 Walker J. M. 334 Walker R. T. 308 320 Walker W. E. 209 Wall P. D. 343 Wallace R. B. 314 Wallach P. 272 Walling C. 65 Wallo A. 204 Walsh C. 40 Walsh L. 101 Walter R. 9 Walther D. 203 Walton D. J. 86 87 Walton D. R. M. 228 272 Walton J. C. 59 62 115 Wan C. C. 291 Wang A. H.-J. 314 Wang J. H. 348 Wang J. T. 54 Wang N. 234 Wang P. C. 248 Warkentin J. 63 Warnhoff E. W. 47 Warning K. 85 Warren S. 237 Warrener R. N. 151 164 Warshel A. 26 96 Washburne S. S. 228 Watanabe A, 275 Watanabe H. 216 Watanabe K. A. 303 308 Watanabe M. 154 Watanabe T. 301 Waterfield A.A. 343 Waterhouse I. 244 Waters D. N. 162 Watkin D. 18 Watson H. A. 197 Watson T. R. 294 Watt I. 48 153 Wattanasin S. 169 Watterson D. M. 348 Webb B. C. 165 Webb E. C. 347 Webber A. 88 Weber E. 199 Weber W. 71 139 Weber W. P. 77 227 Weedon A. C. 103 105 182 Weeks G. 157 Weeks P. D. 197 Wege D. 186 Weichsel C. 91 Weidenhammer K. 161 Weidmann B. 48 268 Weigel L. O. 237 268 Weiner P. 18 308 Weingartner H. 342 Weinreb S. F. 241 Weinreb S. M. 31 283 Weinstein B. W. 195 Weisenfeld R. B. 237 Weisman G. R. 189 Weiss R. 161 Weiss R. M. 26 96 Weissman S. M. 312 Weissmann C. 310 Weith H. L. 314 Weitz H. M. 271 Welankiwar S. S. 186 Welch S. C. 244 Weller H. N. 273 Weller T.270 271 Wellmann J. 93 Wells C. H. J. 165 Wendelberger G. 326 Wendelborn D. F. 247 250 Wender P.A. 34 141 Weng L. 362 Wenkert E. 139 Wenska G. 303 Wentrup C. 68,72,73,74 198 Wenzel T. J. 157 Werner H. J. 17 Werstiuk N. H. 52 Wessels P. L. 291 296 West R. 219 Westermann J. 263 Westheimer F. H. 48 Westmijze H. 266 Wexler B. A. 274 Wharry S.M. 7 White C. T. 128 269 White M. A. 114 211 273 White R. H. 298 White R. L. 297 Whitesides G. M. 222 223 Whitfield J. F. 350 Whitham G. H. 31 Whiting D. A. 289 294 Whitman D. W. 153 Whitsel B. L. 73 Whittle A. J. 248 286 Wholley T. 332 Wiberg K. B. 18 Wicens J. J. 222 Widener R. K. 285 Wieber M. 260 Wiebers J. L. 308 Wiewiorowski M. 3 17 Wightman R.H. 298 299 300 303 Author Index Wilcox C. S. 187 Wild J. 124 Wilhelm E. 140 Wilke G. 206 Wilkinson J. M. 101 117 141 Wille-Hezeleger G. 316 Williams A. 50 Williams B. J. 330 Williams D. L. H. 178 Williams D. R. 274 Williams F. 54 Williams I. H. 26 47 Williams R. E. 320 Williamsen P. 191 Willis C. J. 12 Willis C. L. 293 Willis J. P. 86 Willis W. W. Jr. 252 Willner I. 159 Wilmshurst J. K. 22 Wilson A. A, 44 Wilson G. 295 Wilson H. 38 Wilson R. M. 102 Wilson S. R. 221 237 Wilson T. 177 Wimmer E. 312 Wing R. 314 Wingen R. 161 Winiker R. 56 Winkle M. R. 219 Winkler P. 199 Winkler T. 140 Winne C. R. 306 Winter G. 313 Winter H.-W. 68 198 Wintermayr H.154 Wipff G. 19 21 22 50 150 Wiriyachitra P. 258 Withers G. P. 265 Withers N. W. 293 Witiak D. T. 175 Wittig G. 174 Wlodecki B. 197 Woggon W.-D. 34 297 Wojnowich L. 129 Wolf A. R. 168 Wolf H. O. 351 Wolf J. F. 83 Wolfe J. F. 106 190 Wolff S. 101 152 Wolfsberg M. 25 Wollowitz S. 247 250 Wong C.-K. 248 249 257 268 Wong C. L. 231 Wong H. N. C. 68 Wong J. L. 307 Wong J. T.-F. 355 Wong M. Y. H. 47 Wong S. K. 103 Wong T. W. 329 Wood C. P. 17 Wood H. C. S. 200 Wood G. P. 247 Wood W. A. 356 Woodard R. W. 298 Woods M. 10 Woodward R. B. 184 Woolf C. J. 343 Worley M. C. 163 Woynar H. 54 Wrigglesworth R. 200 Wright A. P. G. 78 Wu R. 313 316 Wubbels G. G. 98 Wudl F. 189 Wunsch E.326 329 Wuthrich K. 337 Wynberg H. 124 Xuong N.-H. 348 Yabe A, 68 Yagi H. 176 Yaginuma S. 302 Yamabe S. 20 74 Yamada K. 163 Yamada S. 283 Yamada T. 142 Yamaguchi R. 308 Yamaguchi S. 129 Yamaguchi Y. 17 18 23 24 70 Yamakawa K. 256 Yamakawa M. 76 Yamakawa S. 76 Yamaki T. 350 Yamamoto G. 59 Yamamoto I. 305 Yamamoto K. 132 144 Yamamoto S. 269 Yamamoto Y. 119 131 193 197 215 230 269 282 Yamamura S. 217 Yamana K. 307 Yamane A. 307 Yamashita A. 145 172 212 Yamashita M. 217 273 Yamauchi K. 307 Yamauchi M. 223 Yamazaki K. 176 Yamazaki N. 126 Yanez M. 16 Yang N.-C. 96 189 Yang T. Y. 227 Yang Gu T.-Y.,'77 Yano T. 119 247 Yansura D. G. 310 Yasuda H. 223 Yasuda M.226 Yasuda N. 223 Yasuhara F. 129 Yasuoka N. 223 Yatagai H. 118 119 215 230 269 282 Yelverton E.. 310 Yimenu T. 278 Yoda N. 206 Yokohama S. 184 Yokoyama Y. 257 Yonehara H. 302 Yonemitsu O. 148 Yonetani T. 348 Yonezawa T. 15 Yoshida A. 184 Yoshida H. 99 Yoshida M. 177 308 Yoshida T. 108 Yoshihara M. 60 Yoshikoshi A. 186 235 Yoshimine M. 18 26 76 Yoshimoto H. 272 Yoshimura Y. 294 302 Yoshioka M. 269 Yoshioka Y. 77 Young D. W. 173 Young I. G. 311 313 Young J. F. 313 Young M. W. 233 Young S. D. 35 128 269 Yu M.-L. 295 Yuan P. M. 334 Yuasa Y. 171 Zabel R. W. 105 182 Zady M. F. 307 Zagorskii V. V. 222 Zahler R. 144 211 Zahner H. 301 Zamir L. O. 294 Zapata A. 265 Zarytova V.F. 317 Zawalski R. C. 56 Zazra J. T. 313 Zazzaron D. 39 Zbiral E. 305 Zeiss H.-J. 269 Zell R. 181 Zeller K.-P. 74 Zellers E. T. 278 Zenk M. H. 295 Zerner B. 165 Zia A. 135 Ziegler M. L. 161 Zima G. 248 274 Zimmerman H. E. 96 98 Zimmermann G. 125 Zissmann E. 297 Zlotogorski C. 67 174 Zoratti M. 67 166 Zuger M. 270 Zupancic J. J. 73 Zurer P. St. J. 144 Zwanenburg B. 75 Zweifel G. 113 229 271 Zweig A. 168 Zylber J. 305

ISSN:0069-3030    

DOI:10.1039/OC9807700363

出版商:RSC    

年代:1980

数据来源: RSC