摘要:

Analogs of oxytocin containing tetrahydroisoquinoline carboxylic acid (Tic) of L or D configuration in position 2 were synthesized and their biological activities were tested. Both analogs showed negligible agonist activity in uterotonic, galactogogic, and pressor assays, but they arein vitrouterotonic inhibitors. In comparison with oxytocin analogs containingl‐ or D‐phenylalanine in position 2, the analog with the D‐configuration of the conformationally fixed aromatic residue has significantly increased inhibitory activity which suggests that the proper conformation for the interaction with the receptor, but not for its activation, was stabilized.1H NMR and CD studies, supported by theoretical calculations, suggest that the conformational properties of the analog containing D‐tetrahydroisoquinoline carboxylic acid are similar to those of [2D‐phenylalanine

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01289.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

A new nomenclature is proposed that allows a precise and concise description of mass spectrometric fragments derived from peptides. The nomenclature differs from existing methods by specifically accommodating (I) extended or unusual amino acid residues, (2) cyclic‐ and cyclodepsipeptides, and (3) residues contained in branches of the main chai

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01290.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The sea anemoneStichodactyla helianthusneurotoxin I, a 48‐residue polypeptide, was synthesized by automated solid phase methodology. The fully reduced polypeptide was subsequently refolded in the presence of a glutathione oxidoreduction buffer to the biologically active species containing three disulfide bonds. The overall yield after rigorous purification was 12.5%. The circular dichroism (CD), and proton nuclear magnetic resonance (1H NMR) spectra of the HPLC‐purified synthetic toxin were indistinguishable from those obtained concurrently with the natural toxin. A subtilisin digest of the synthetic neurotoxin generated peptide fragments identical to that of a sample of the natural toxin subjected to the same treatment. The toxicity of the synthetic polypeptide was identical to that of the natural toxin (crab LD50, 3.1μg/kg). The equilibrium dissociation constant (28 nM) for interaction of the synthetic toxin with crab axolemma vesicles was nearly identical to that of the natural toxin (25

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01291.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The process of insulin aggregation in neutral solutions was studied by dynamic light scattering. Solutions of different concentrations were subjected to thermal and mechanical stress (37°, rotation) for a period of 4 weeks. The starting solutions contained exclusively one particle distribution of insulin in the association equilibrium with hexamers as the largest structures. After a lag period of about 8 days the solutions showed continuously increasing scattering intensities but did not evolve perceptible turbidity within the experimental period. A more rapid increase in scattering intensity was observed in diluted than in concentrated solutions. The analysis of scattering data unexpectedly revealed that insulin species did not grow continuously. After the lag period one additional relatively restricted size distribution with particles of a mean radius of about 100nm was found, the amount of which increased continuously with time. The occurrence of these particles seems to be related to adsorption phenomena of insulin to the solid interface. We assume the 100nm‐class of aggregates to be a transient state in the physical destabilization process of insulin solutio

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01292.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The use ofNα‐tert.‐butyloxycarbonyl‐Nπbenzyloxymethylhistidine in peptide synthesis resulted in significant levels of several different side products attributable to the generation of formaldehyde during the hydrogen fluoride cleavage reaction. Methylated impurities in a decapeptide were isolated and identified. These methylated impurities were attributed to the use of the benzyloxymethyl protecting group for the histidines, since the impurities did not form when the dinitrophenyl protecting group was used. Also, peptides containing benzyloxymethyl‐protected histidines in addition toN‐terminal cysteines quantitatively yielded their respectiveN‐terminal thiazolidine derivatives upon isolation from standard hydrogen fluoride cleavage mixtures. Thiazolidine ring formation was circumvented by including in the cleavage reaction a formaldehyde scavenger such as cysteine hydrochloride

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01293.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Insulin‐like growth factor I (IGF‐I), a protein of 70 amino acid residues and 3 cystine bridges, has been synthesized by two solid phase Boc methods. The first method usedN‐methylpyrrolidinone as the solvent with single coupling cycles while the second synthesis used dimethylformamide and dichloromethane as the solvents with a double‐coupling protocol. In both cases, trifluoroacetic acid/trifluoromethanesulphonic acid cleavage of the peptide from the resin was employed. Purification of the cleavage products followed by removal of the S‐acetamidomethyl protecting groups gave reduced peptides which were then oxidized under conditions favouring the formation of the correct disulphide bonds. The purified synthetic IGF‐I peptides were full agonists of natural IGF‐I in a radioimmunoassay, in an IGF‐I radioreceptor assay, in a bioassay which measures the stimulation of protein synthesis in rat L6 myoblasts and in an IGF‐binding protein competitive binding assay. Moreover, in each of these assays, the synthetic IGF peptides were found to be at least 70% as poten

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01294.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The solution phase synthesis of theSaccharomyces cerevisiae a‐mating factor and nonfarnesylated and nonmethylateda‐factor analogs are reported. Thea‐factor, a lipopeptide with the sequence Tyr‐Ile‐Ile‐Lys‐Gly‐Val‐Phe‐Trp‐Asp‐Pro‐Ala‐Cys(S‐Farnesyl)OCH3was synthesized by the condensation of the amine terminal protected decapeptide with the carboxyl terminal farnesylated dipeptide using benzotriazol‐l‐yl‐oxy‐tris‐(dimethylamino)‐phosphonium hexafluorophosphate (BOP reagent) as the coupling agent. The synthesis of the decapeptide involved 5 + 5 fragment coupling with the BOP reagent and the successful application of 9‐fluorenylmethyl ester(OFm) and 9‐fluorenylmethoxycarbonyl(Fmoc) groups for the protection of Asp and Lys side chains and Tyr α‐amine and of phenacyl esters (OPa) for α‐carboxyl protection. The OFm and Fmoc groups tolerated repeated couplings and were completely stable to zinc powder in acetic acid, a condition under which the OPa group was removed. The synthesis of the nonfarnesylateda‐factor was accomplished by the coupling of the decapeptide with tetrapeptide (Ala‐CysOCH3)2followed by the deprotection of the OFm and Fmoc groups with piperidine and the cleavage of the disulfide bond with zinc powder in acetic acid. The nonmethylateda‐factor was prepared by 10 + 2 fragment coupling using OFm protection of the dipeptide carboxyl group followed by removal of all protecting groups with piperidine. Attempts to saponifya‐factor were not successful. The synthetic nonfarnesylated and nonmethylateda‐mating pheromones were 100‐1000 times less active than thea‐factor, indicating that although the methyl ester and the farnesyl group are not essen

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01295.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

The synthesis is reported of a series of glutamyl peptide analogs of the model substrate H‐Ser‐Glu‐Glu‐Glu‐Glu‐Glu‐OH of casein kinase‐2 (CK‐2). A convenient HPLC method for the separation of slightly different acidic peptides is also reported. The site specificity of yeast casein kinase‐2 (Y‐CK2) is examined with the aid of synthesiz

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01296.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

In solid‐phase peptide synthesis usingNα‐Boc‐Nim‐tosyl‐histidine (Boc‐His(Tos)), byproducts having extra Gly residues in the peptide chain were observed at a high rate. When a Boc‐amino acid such as Asn was incorporated after assembly of Boc‐His(Tos), theNim‐tosyl group was partially or fully cleaved by an activating agent, 1‐hydroxybenzotriazole. In the successive coupling reactions, Boc‐Gly was incorporated into the freeNimring as well as the α‐amino function, and theNim‐Gly was then transferred to the α‐amino group of Gly of the peptide chain after removal of these Boc groups to give extra Gly residues at the position of Gly. This was observed in only the coupling reaction with Boc‐Gly and could be circumvented using a more stableNimprotecting group for Hi

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01297.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY

摘要:

Proteinase R and T purified fromTritirachiam albumlimber were characterized in comparison with proteinase K using circular dichroism (CD), enzyme activity, thermal melting, and sodium dodecylsulfatc polyacrylamide gel electrophoresis (SDS‐PAGE). CD analysis suggested that these three proteins possess some β‐sheet structure, with little α‐helix except for proteinase R which showed about 14%α‐helix. SDS‐PAGE and gel filtration in 0.1% SDS indicated that proteinase T and K are resistant to SDS‐induced unfolding similar to subtilisin. Thermal denaturation experiments showed the melting temperature for proteinase T to be 67° and that for proteinase K to be 65° in the absence of Ca2+, with higher melting temperatures in the presence of Ca2+. However, the enzyme activities of proteinase T and R were significantly lower than those

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1990.tb01298.x

出版商:Blackwell Publishing Ltd    

年代:1990

数据来源: WILEY