摘要:

This paper is part of a series on synthesis of suitably protected peptides covering the 66–104 sequence of horse heart cytochromec.It describes the preparation, by conventional procedures, of a partially protected Nα‐benzyloxycarbonyl‐undecapeptide hydrazide corresponding to the sequence from 66 to 76 (Fragment F), which represents a building block for the synthesis of the entire 66 – 104 sequence.Moreover, the preparation is described of a partially protected pentadecapeptide corresponding to the sequence region 66 to 80, which represents the key peptide for the semisynthesis of the same COOH‐terminal sequence utilizing the natural 81 – 104 N‐trifluoroacetylated

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02779.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A solution synthesis of Z‐Gly‐Thr‐Lys (Tfa)‐Met‐Ile‐Phe‐Ala‐Gly‐Ile‐Lys (Tfa)‐Lys (Tfa)‐NHNH‐Boc corresponding to the sequence 77–87 of horse heart cytochrome c is described. The protected undecapeptide was obtained from intermediate hepta‐ and tetrapeptide f

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02780.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A solution synthesis is described of the partially protected Nα‐benzyloxycarbon‐ylheptadecapeptide Z‐Lys (Tfa)‐Thr‐Glu‐Arg‐Glu‐Asp‐Leu‐Ile‐Ala‐Tyr‐Leu‐Lys (Tfa)‐Lys (Tfa)‐Ala‐Thr‐Asn‐Glu (OBut)‐OButcorresponding to sequence 88–104 of horse heart cytochromec. The synthesis is achieved through the preparation of two subunits H1(Sequence 88–96) and H2(Sequence 97–10

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02781.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Circular dichroic (CD) spectra of the glycoprotein hormone subunit, lutropin‐α, have been obtained under denaturing conditions (6 M guanidinium chloride, GdmCl) with the disulfides intact, reduced, and reduced and S‐carboxymethylated. Above 260 nm, these spectra are similar (although not identical), showing that the disulfide chromophores do not contribute appreciably to the near ultraviolet CD spectrum under denaturing conditions. However, these spectra differ considerably from that of native lutropin‐α over this spectral region demonstrating that the tertiary structure of lutropin‐α has a major influence on the near ultraviolet CD spectrum. The magnitude of the 232.5 nm positive CD extremum of lutropin‐α was found to increase with increasing GdmCl concentration and with decreasing temperature. Between 5d̀C and 45d̀C, the ellipticity [θ] at 232.5 nm changed in a linear fashion with temperature; at other wavelengths the thermal changes in [θ]were quite small. [θ] at 232.5 nm increased by about 80% over a 3 M GdmCl range; in contrast, [θ]at 216 nm (indicative of β‐structure) exhibited maximal changes over a 0.5 M GdmCl range. These results indicate some conformational flexibility in lutropin‐α. The positive 232.5 nm CD extremum has been assigned to one or more tyrosyls which are influenced by an intact disulfide. The latter was demonstrated by showing that reduced and S‐carboxymethylated lutropin‐α failed to

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02782.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Eleven unsaturated peptides, containing one or two dehydro‐phenylalanyl (dehydro‐Phe) residues and a C‐terminal L‐amino acid have been hydrogenated in the presence of palladium‐on‐charcoal.Hydrolysis of the saturated peptides thus obtained gave optically active phenylalanine showing the occurrence of asymmetric induction during the hydrogenation.Both mono‐unsaturated dipeptides and doubly unsaturated tripeptides with L‐Glu, L‐Leu and L‐Val as chiral end‐group afforded L‐Phe in 40–50% optical yield. In the case of the tripeptide N‐acetyl‐(dehydro‐Phe)‐(dehydro‐Tyr)‐L‐Glu the asymmetric induction was higher (70%) for the unsaturated residue which is farther from the chiral end‐group along the peptide chain.The results are discussed on the bases of Prelog rule and the rigid dissymmetric confor

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02783.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Highly purified human alpha‐1‐antitrypsin (phenotype MM) was obtained by an original method of preparative electrophoresis. The criteria of homogeneity were assured by one arc in crossed immunoelectrophoresis and one band on polyacrylamide gel. A uniqueN‐terminal amino acid (pyroglutamic acid) and a uniqueC‐terminal residue (lysine) were identified. Determined by gel electrophoresis, its molecular weight was 47,000

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02784.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The behaviour of the major protein of sesame seed (Sesamum indicumL.) α‐globulin has been studied in a cationic detergent, cetyl trimethyl ammonium bromide solution. Up to a critical detergent concentration the protein is precipitated from solution, above which redissolution of the protein is observed. Sedimentation velocity patterns indicate the presence of higher aggregates in the detergent concentration range 5 times 10‐5– 1 times 10‐3M. These are considered to be the soluble precursors of the insoluble aggregates. Fluorescence measurements show that tryptophanyl groups of the protein which are in contact with the aqueous phase are perturbed by the detergent. The difference spectra of the protein in higher concentration of detergent indicate considerable red shift in the spectrum. Spectrophotometric titration of phenolic groups in 1 times 10‐2M CTAB indicate that a conformational change in the protein has t

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02785.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Polypeptides with alternating L‐ and D‐amino acid residues can take up stereochemically satisfactory coaxial double‐helical structures, both antiparallel and parallel, which are stabilized by systematic interchain NH O hydrogen bonds. Semiempirical energy calculations over allowed regions of conformational space have yielded the characteristics of these double‐helices.There are four possible types of antiparallel double‐helices ‐ A3, A4, A5and A6, withn, the number of LD peptide units per turn, around 2.8, 3.6, 4.5 and 5.5 respectively, while for the parallel double‐helices there are two types, P3and P4, having similar helical parameters as in A3and A4. The hydrogen‐bonding scheme restricts the pitch in all the models to the narrow range of 10.0 to 11.5 Å. All these helices have large central cores whose radii increase proportionately withn. In this respect, A3and A4are suitable models for the structure of gramicidin A.In terms of their relative energies, antiparallel double‐helices are marginally more stable than those with parallel strands. Our results indicate that the energy differences amongst the members in the antiparallel family are not significant and thus provide an explanation for the polymorphism reported for poly(γ

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02786.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A method has been developed for selectively preparing the carboxyl‐terminal tryptic peptide of proteins by cleavage at arginyl residues. The succinylated protein is digested with trypsin and the peptides produced are maleylated. Maleylated peptides are then submitted to cation‐exchange chromatography in urea at low pH and ionic strength. Arginine‐containing peptides are retained by the resin. The carboxyl‐terminal peptide emerges unretarded and in pure form. This method has been applied to four proteins of known sequence. Yields as high as 88% have been o

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02787.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Arginine residues (5.5 out of 6) of the trypsin‐kallikrein inhibitor from bovine organs (Kunitz inhibitor) were selectively modified by reaction with 1, 2‐cyclo‐hexanedione in sodium borate buffer, pH 9.0. The modified inhibitor is still highly active in inhibiting trypsin and chymotrypsin at 1:1 inhibitor: enzyme molar ratio and full inhibition was achieved at slightly higher molar ratio. The extent of correct refolding, upon reoxidation, of the reduced, arginine‐modified inhibitor is diminished and regeneration of two arginines occurred under the reduction conditions.The stability constants and the standard‐free energies of binding of the complexes between trypsin, or chymotrypsin, and the native, the arginine‐modified and the reduced and reoxidized arginine‐modified inhibitor have been determined from inhi

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02788.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY