摘要:

Entirely beaded poly‐N‐acrylylpyrrolidine‐co‐bisacrylyl‐1, 2‐diaminoethane‐co‐N‐acrylyl‐1, 6‐diaminohexane‐HCl(PAP), a new resin on which to perform peptide chemistry, has been prepared by reverse phase suspension polymerization in quantitative yield. In addition to being a superior support to polystyrene, albeit readily adaptable to current techniques of peptide synthesis, its versatility has been further extended by the introduction and use of new peptide‐to‐polymer linking groups, which allow the use of the bidirectional approach to peptide chemistry. One such linkage, which connects the side chain of cysteine to PAP via an acid resistant S‐carbamoyl bond, was used in a bidirectional synthesis of deamino‐oxytocin. PAP solvates and swells in solvents with wide‐ranging polarities, including aqueous media. Thus, peptide coupling reactions were performed in organic media of high and of low polari

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01857.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

A modified procedure for the preparation of the S‐sulfonates of the A‐ and B‐chains of insulin and their conversion to the sulfhydryl forms by tri‐n‐butyl‐phosphine is described. Air oxidation of the sulfhydryl forms of the A‐chain in dilute solution (0.2 mg/ml) either in the presence or absence of urea at pH 9.0 yields primarily monomeric, intrachain disulfides. Similar treatment of the reduced B‐chain yields monomeric, intrachain disulfide in 7murea but a large number of oligomeric, interchain disulfides in the absence of urea. Electrolytic reduction of insulin in 7murea at pH 8.5, followed by oxidation of the sulfhydryls in dilute solution in 7murea at pH 9.0 yields primarily a mixture of the monomeric, intrachain disulfides of the A‐chain and of the B‐chain which can be separated by chromatography on Sp‐Sephadex in acidic urea. The rate of the oxidation of the sulfhydryls of the two separate chains was much slower and less complete than that reported for the two chains crosslinked by the carbony

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01858.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The chemistry of the formation of 2‐thiohydantoins on the carboxyl terminal of peptides or proteins was investigated. It was found that thiocyanic acid was much more reactive for the formation of 2‐thiohydantoins than were the thiocyanate salts. The physical reasons for this observation are explained. The kinetics of the reaction of a number of proteins, and some of their fragments, with thiocyanic acid were also determined. Simple and safe procedures for the preparation of anhydrous thiocyanic acid solutions were devised. The prospective application of these procedures to sequencing from the carboxyl terminal of a polypeptide is discus

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01859.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The C‐terminal octapeptide of cholecystokinin‐pancreozymin and its analogues in which the methionine residues were successively replaced by methoxinine have been synthesized. When these analogues were tested for their gallbladder‐contraction activity in an in vitro system the following relative potencies were observed: [Mox3]‐CCK‐PZ 8 (95%), [Mox6]‐CCK‐PZ 8 (5%) and [Mox3, Mox6]

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01860.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Oxytocin (OT) was synthesized employing the solid phase method. Resins made of copolymers of polystyrene‐1%‐crosslinked with divinylbenzene gave better yields (73–95%) of Z‐Cys(Bzl)‐Tyr(Bzl)‐Ile‐Gln‐Asn‐Cys(Bzl)‐Pro‐Leu‐Gly‐NH2(I) than 2%‐crosslinked resins (10–56%). Reduction of I with Na‐liq. NH3and oxidation with I2‐MeOH at –40° minimized dimer and polymer formation, and resulted in good yields (49–54%) of OT. The large volumes of MeOH required when several grams of I are reduced and then oxidized were rapidly evaporated in vacuo, and the residue was desalted by dissolving the peptide in a small volume of glacial acetic acid and filtering to remove the salt. OT was purified by adsorption chromatography on a silica gel column with combinations of MeOH‐CHCl3of graded polarity. Oxytocin elutes with 33% MeOH‐CHCl3. After two purification steps by adsorption chromatography, the resulting OT was found to be homogeneous. The hormone was characterized chem

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01861.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Comparisons are described between Bungarus caeruleus venom and the actual venom from which a putative marker for the cholinergic ionophore, called ceruleotoxin, was isolated. The venoms are shown to be different by two procedures for ion exchange chromatography and by isoelectric focusing on polyacrylamide gel. The activities of the purified “ceruleotoxin” as an inhibitor of acetylcholine receptor‐mediated ion flux and as a phospholipase have been reported (Bon&Changeux, 1977b). The results reported herein suggest that this toxin is from an unknown o

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01862.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

As part of a study of the peptidase content of Escherichia coli K‐12, two peptidase‐deficient amino acid auxotrophs isolated and characterized by Miller as pepD‐(strain CM17) and pepD‐pepN‐pepA‐pepB‐pepQ‐(strain CM89) were examined for the presence of several peptidases previously obtained from strain K‐12 in this laboratory. The soluble fraction of each mutant was found to lack the broad‐specificity strain K‐12 dipeptidase DP and the strain CM89 fraction also lacked activity characteristic of the strain K‐12 aminopeptidases AP, L, and OP; like strain CM17, strain CM89 contained the tripeptide‐specific amino‐peptidase TP. Strain CM89 (but not CM17) appeared to contain little if any activity attributable to the ribosome‐bound aminopeptidase I of strain K‐12. Whereas loss of DP, AP, OP, and aminopeptidase I activity may be attributed to the pepD‐, pepB‐, pepN‐, and pepA‐mutations, respectively, the reason for the loss of L activity remains uncertain. Grown responses of strain CM89 in liquid media containing di‐ or tripeptides were in accord with absence of enzymes catalyzing rapid hydrolysis of dipeptides. In synthetic liquid media supplemented with the required amino acids per se or with peptone, cultures of both CM strains grew more slowly than strain K‐12 and produced smaller cel

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01863.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

Investigations have been carried out on the complex formed between sorghum Inhibitor III and α‐chymotrypsin by physico‐chemical methods. An apparent dissociation constant (Ki) of 4.0 times 10‐8M has been calculated for the complex. This enzyme‐inhibitor complex was isolated by gel filtration on Sephadex G‐75 and a molecular weight of 48,000 was estimated for the complex. The formation of the complex was accompanied by spectral changes in the 270–300 nm region of the spectrum. Preliminary evidence suggests that the sorghum Inhibitor III is structurally altered when it is incubated with α‐chymotrypsin. Catalytically inactive derivative of α‐chymotrypsin and trypsin, as well as their zymogens, did not interfere with the activity of the sorghum inhibitor towards the native enzymes. Sorghum Inhibitor I was shown to be a ‘double‐headed’ inhibitor since it inhibits both trypsin and α

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01864.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

LMW kininogen was isolated from whole human plasma by gel filtration on Sephadex G‐200 (Kav0.34) followed by DEAE‐chromatography according to earlier established methods. Further purification was performed with specific Sepharose‐antibody columns to remove protein contaminants, avoiding procedures which may denature kininogen. The microheterogeneity was investigated by isoelectric focusing in column in the pH‐gradients 3.5–10, 4–6 and 3.5–5. Kininogen components were determined by single radial immuno‐diffusion against monospecific anti‐human kininogen serum, in comparison with focusing of whole plasma. 40% of isolated as well as whole plasma kininogen focused at pl 4.5; the respective focusing ranges were pI 4.4–4.7 (60–80%) and pI 4.3–4.6 (92%). The results were verified by crossed immuno‐electrophoresis. The pI 4.5 component is apparently the main native form of human kininogen as shown by focusing of whole human blood bank plasma. Earlier described difficulty of separating kininogen and α2HS‐glycoprotein was verified by crossed immunoelectrophoresis which showed approximately seven kininogen components after focusing in polyacrylamide gel electrophoresis at pI 4.5–5.0 and four

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01865.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY

摘要:

The crystal structures of a number of globular proteins are currently available. An analysis of the distribution of side‐chains among different allowed conformations in these proteins has been carried out. The observed conformations of individual residues are discussed on the basis of well‐known stereochemical criteria. The population distribution of side‐chains in different allowed regions in conformational space can be explained largely on the basis of simple steric considerations. In addition to examining the conformational behaviour of individual residues, some population distributions of conformational angles of general interest involving groups of residues have also been ana

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1979.tb01866.x

出版商:Blackwell Publishing Ltd    

年代:1979

数据来源: WILEY