摘要:

The stability of the diphenylindenonesulphonyl (disyl) derivatives of tryptophan, proline, hydroxyproline, histidine, serine, threonine and aspartic acid, as well as of glycine, alanine, α‐amino butyric acid, phenylalanine, valine, leucine and isoleucine to acid hydrolysis is studied. The results indicate that the disyl derivatives are much more stable in comparison with the corresponding DNP‐and DNS‐derivatives. Hence, the dysil‐chloride method possesses definite advantages over these widely used methods for determination of N‐terminal groups, not only because of its higher sensitivity, but also because of the higher stability of the disyl derivatives of amino acids to acid

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02796.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The molecular weight of the constituent glycopolypeptide chain of T‐H glycoprotein was determined by sedimentation equilibrium under two entirely different sets of denaturing conditions. For both sets of denaturing conditions, the average molecular weight estimated for T‐H glycopoly peptide was 74,000. The gel chromatographic behavior in 6 Mguanidium chloride of T‐H glycopoly peptide with disulfide bonds intact as compared with its gel chromatographic behavior with disulfide bonds broken indicated that the glycopolypeptide is highly constrained by intrachain disulfide

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02797.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A snake cardiotoxin from the venom of the Formosan cobra, Naja naja atra, is a basic polypeptide. The protein can be denatured in 6.0 M guanidine hydrochloride or at elevated temperatures. Its conformation remains virtually the same in solvents of lower polarity than water such as 1, 2‐ethanediol or 1‐propanol and 1, 2‐ethanediol (1:1 v/v). The circular dichroism spectrum is atypical in water in that the peptide chromophores show a small negative CD band at 214 nm and a large positive one at 195 nm. To some extent the CD pattern resembles that of the β‐form but differs in specific positions and magnitudes. Considering that the theoretical CD of the reverse β‐bend and the characteristics of model polypeptides in β‐form manifest a similar pattern, we suggest that cobra cardiotoxin is rich in β structure including β pleated‐sheets

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02798.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

As inferred from13C,1H n.m.r. data, CD measurements and ion‐binding experiments, the title molecule can assume two major C2symmetric conformations. One of these has an all‐trans X‐Pro peptide backbone with two 1 4 intramolecular H‐bonds and represents the predominant (≥ 95%) form in D2O and nonpolar (CD3CN) solvents. Stabilized by specific solvent‐solute interactions, the other conformer becomes competitive (45%) in DMSO solution. It is shown to possess a four‐cis X‐Pro skeleton and no intramolecular H‐bonds. The Mg++ complex of the cyclic peptide in CD3CN is again C2symmetric and its formation proceeds via a slow trans → cis isomerization of two

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02799.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The activity of poly (Cys‐Ser‐Phe‐Glu‐Glu) and related polypeptides as models of cysteine‐proteases towards p‐nitrophenylacetate was studied. The reaction leads to the formation of an S‐acetylated form which proved to be quite stable, except at very high pH values. The presence of imidazole groups in the neighbourhood of sulfhydryl functions seems to result in an enhancement of the activity, which we attributed to a cooperative interaction. However, this interaction has no effect upon the S‐deacylation rate. In the case of cysteine we found that the reaction with NPA occurred through a S to N acyl shift. Our results lead us to suggest that, unless convincing proofs of deacylation are given, the various models of cysteine‐proteases studied so far do not behave as

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02800.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A series of analogs of thyroliberin (TRH) ([L‐3Pro3]‐TRH, [D‐3Pro3]‐TRH, [L‐3‐MeHis2, L‐3Pro3]‐TRH) in which proline was replaced by L‐ or D‐3, 4‐dehydroproline was synthesized. The analogs exhibited approximately the same biological activity as the corresponding proline‐containing peptides. These analogs and others in which 3, 4‐dehydroproline is present at the NH2‐terminal, COOH‐terminal or internal positions in the peptide were successfully reduced with deuterium or tritium to provide the 3, 42‐H2‐proline or 3, 43‐H2‐proline analogs, respectively, with near theoretical values of substitution. A novel procedure for the chemical resolution of DL

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02801.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A simple and sensitive method for determination of amide groups in proteins is presented. The method employs a combination of a simple microdiffusion technique and the indophenol method for ammonia determination. A similar ammonia analysis was used for total nitrogen determination after Kjeldahl digestion. The results from the amide group and total nitrogen analyses, together with previously published amino acid and carbohydrate analyses, were used to estimate a value of 12.4 for the specific extinction coefficient, E1%280nm, of dopamine β‐monooxygenase from bovine adrenal medul

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02802.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The carbohydrate side chains of mucus‐type glycoproteins are O‐glycosidic bonds between N‐acetylgalactosamine to the hydroxyl groups of serine and threonine in the protein core. The alkaline catalyzed β‐elimination reaction, in the presence of sodium borohydride, is used for determining the number of side chains.The present paper presents a study of the quantitativeness of the alkaline borohydride procedure, using four parameters: the loss of seryl and threonyl residues, the formation of alanine and 2‐aminobutanoic acid; the decrease in N‐acetylhexosamine and the recovery of the amino sugar alcohols. Bovine, ovine and porcine submandibular glycoproteins were studied.Evidence is presented for the existence of N‐acetylglucosamine involvement in O‐glycosidic linkages to serine and threonine.Results for the relative rates of β‐elimination indicate that serine‐linked glycosides are released more rapidly than threon

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02803.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

To confirm the structure of AM‐toxin I (a phytotoxic cyclotetradepsipeptide) the proposed peptide was prepared by a conventional method. The synthetic peptide and natural AM‐toxin I were identical as regards t.l.c., u.v., mass spectra and biological activity in causing necrosis on apple leaves. A prepared dimer of AM‐toxin I showed extremely weak activity; the relationship between the ring size and biological activity of AM‐toxin I is di

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1977.tb02804.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY