摘要:

The pentadecapeptide fragment, Trp‐Val‐Leu‐Ala‐Tyr‐Glu‐Pro‐Val‐Trp‐Ala‐Ile‐Gly‐Thr‐Gly‐Lys, which constitutes a part of the active site of rabbit muscle triosephosphate isomerase has been synthesized. It does not exhibit any catalytic activity typical o

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02442.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The portion of echnida sublingual glycoproteins which could be solubilized was fractionated by electrophoresis in polyacrylamide gel and by filtration on a column of Sephadex G‐100. Analyses for carbohydrate and amino acid are given and are compared with those of the submaxillary mucins of cattle, dog, pig and sheep. The molar ratio of galactosamine to sialic acid was roughly 1:1 in the echidna fractions, the sialic acid was N‐acetyl‐neuraminic acid, and there was very little neutral sugar. Proline was relatively high in amount, and isoleucine, half‐cystine, methionine, leucine, tyrosine, and phenylalanine were absent or present to a very small extent. The material was weakly antigenic in the

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02443.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

A new amino protecting group, the methylsulfonylethyloxycarbonyl (Msc) group, is described which combines well with other familiar groups (benzyloxycarbonyl, t‐butyloxycarbonyl) in peptide syntheses. Its main characteristics are an extreme acid stability, a high base lability and a high polarity which enhances solubility in polar solvents including water. The group resists catalytic hydrogenolysis but does not poison the catalyst. It has good crystallizing properties. Application in peptide synthesis is exemplified in the synthesis of Msc‐Phe‐Arg‐Trp‐Gly‐OMe.HCl. Deprotection of the masked tetrapeptide was accomplished within 5 sec with a 1.0 N solution of base (OH‐and OCH3‐). A reaction scheme for the cleavage of the gro

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02444.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Two tripeptides and one dipeptide, protected except at the carboxyl ends, have been prepared in solution and used as intermediates in a new synthesis of bradykinin on a solid support. Condensation of the two tripeptides to the resin was effected in satisfactory yield with dicyclohexylcarbodiimide plusN‐hydroxysuccinimide. The partial epimerization that might occur by such an approach was explicitly verified to be without practical importance in this case. The crude product contained only traces of impurities and yielded, after purification, bradykinin of high purity. Both the crude and purified bradykinin exhibited full biological activit

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02445.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

A theoretical method is developed by which the character of the process of protein denaturation (e.g., whether or not it is of the all‐or‐none type) can be discussed in terms of conformation of native proteins and the forces stabilizing it. An important role is played by a quantity S(H): entropy of a protein molecule in solution in the conformational states with a given value of enthalpy H. It is demonstrated that the all‐or‐none type denaturation of proteins is a rather direct consequence of the globularity and specificity of the native conformations. Denaturations with significant intermediate states are discussed. Denaturations induced by added denaturants are also di

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02446.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

At pH 7.0 the alkalinemesentericopeptidasehas ultraviolet absorption spectrum with a minimum at 251 nm and a maximum at 280 nm and no visible absorption. From the tyrosine to tryptophan ratio a value of 3 tryptophyl residues per mole of protein is obtained. The molar extinction coefficient at 280 nm is 3.55 times 104M‐1cm‐1. Spectrophotometric titration studies show that the molecule ofmesentericopeptidasecontains seven phenolic groups with a pKapp= 9.92 and four to five groups with a pKapp= 11.96. Denaturing agents, such as 5 M guanidine hydrochloride or alkali, normalize the ionization of the tyrosyl residues. There is a good correlation between the spectrophotometric titration data and the results for the reactivities of the tyrosines inmesentericopeptidasetowards tetranitromethane. The correlation is explained by the mechanism of nitration. Conclusions about the state of the tyrosyl residues and the three‐dimensional structure ofmesentericopeptidaseare

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02447.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Globular proteins in the native state are assumed to behave as continuous elastic spheres in the low frequency breathing motions. Reasonable values of Young's modulus E = 1011dyne/cm2and the radius of the sphere r0= 20 Å, yield a wave number of 26 cm‐1for the fundamental vibration of the sphere. The peak at around 30 cm‐1in the laser Raman spectra of native α‐chymotrypsin and pepsin observed by Brown et al. might be assigned to the breathing motion which the native proteins undergo as continuous elastic

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02448.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

Highly purified preparations of the 3α‐hydroxysteroid:NAD‐ oxidoreductase (E.C.1.1.1.50) fromPseudomonas testosteroni(ATCC 11996) which consist of two major isoenzymes, with traces of a third, have been split into two enzymatically inactive polypeptides A and B by the use of sodium dodecylsulphate, urea and guanidinium hydrochloride. Both polypeptides have a molecular weight of 25,000 ± 2,500 as shown by thin‐layer gel chromatography and ultracentrifugations. They differ, however, in charge as shown by electrophoresis on cellulose acetate strips in the presence of 8 M urea. Each of the isoenzymes, have molecular weight of about 50,000 and thus consist of two subunits. The presence of the three isoenzymes may be explained by the following combinations of the subunits AA, AB and BB.Close to 100% of the original activity towards the three substrates, androsterone, tetrahydrocortisone and desoxycholate could be restored within 24 h when the inactivated enzyme was diluted in order to remove the effect of the den

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02449.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

The denaturation reaction of 6‐phosphogluconate dehydrogenase (6‐phospho‐D‐gluconate: NADP oxidoreductase (decarboxylating EC 1.1.1.44) fromB. StearothermophilusandE. coliin 8 M urea has been compared. The rates of denaturation were evaluated from the fluorescence quenching that occurs at 334 nm. The thermophilic enzyme has been found about ten times more resistant to the action of the denaturating agent, and showed a biphasic denaturation process, whereas theE. colienzyme followed a single first‐order

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02450.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1975.tb02451.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY