摘要:

Bovine neurophysin II (BNP‐II), a major neurohypophyseal hormone‐binding protein in the cow, was isolated from acetone‐dried posterior pituitary powder by gel filtration, ion exchange chromatography and preparative disc electrophoresis. The single‐chain protein is composed of 97 amino acids, possesses a molecular weight of 10,029, and contains seven disulfide bonds. The fully S‐alkylated protein, S‐carboxamido‐[C]‐ methylcysteine BNP‐II ([C]BNP‐II), was subjected to 80 automated cycles of the Edman degradation with positive identification of every amino acid residue through 65 cycles and many identifications through 80 residues. [C]BNP‐II was digested with chymotrypsin and the peptides were isolated by gel filtration and purified by ion exchange chromatography. A 55‐amino acid C‐terminal chymotryptic peptide was sequenced through 46 residues by automated Edman degradations producing a 38‐amino acid overlap with the sequence of [C]BNP‐II. This established the sequences of the first 88 residues of the protein. A chymotryptic nonapeptide was sequenced from NH2‐ to COOH‐terminus by manual Edman degradations which established the sequence through residue 94. COOH‐terminal analysis of aminoethylated BNP‐II elucidated the tetrapeptide sequence and produced an overlap with the sequenced chymotryptic nonapeptide, completing the proposed amino acid sequence, which is supported by amino acid compositions of three other

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02352.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The chromogenic substrate, N‐acetyl‐DL‐phenylalanine‐β‐naphthyl ester (APNE), used in trypsin or chymotrypsin studies, has been employed to identify neutral peptide hydrolases in barley by immunoelectrophoretic analysis. Enzyme activity was observed in proximal (embryo part) and distal (endosperm part) portions of barley grains before and after germination. The proximal portion contained all detectable activity in the ungerminated seed. This enzyme migrates strongly towards the anode. During germination a new enzyme is formed which hydrolyzes the same substrate but is electrophoretically different from the enzyme found in dormant grains (it is more neutral or cathodic). The newly‐formed enzyme appears in the proximal part of the seed after 34 hours of germination and in the distal part after 96 hours. This enzyme does not appear to be a carboxypeptidase but may be related to one (or more) of the reported barley ami

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02353.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

After short peptic digestion of bovine serum albumin between pH 3.6 and 3.9, a limited number of well defined fragments are found. The isolation and characterization of some fragments, probably placed in the C‐terminal part of albumin, have been given in a previous paper. This paper describes the isolation, characterization and localization of a number of N‐terminal fragments of bovine serum albumin. The investigation comprises molecular weight determination, amino acid analysis, N‐terminal amino acid determination, copper binding studies and SH‐group determination. It is concluded that cleavage of albumin by pepsin between pH 3.6 and 3.9 preferentially occurs in the C‐terminal moiety of albumin. This leads to the appearance of large fragments with the same N‐terminal end as albumin. The mechanism of the digestion by pepsin is discussed in relation to the structural model of albumin and the conformational change at low pH (N‐

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02354.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

The rates of deamidation in pH 7.5, 0.15 M, 37.0°C phosphate buffer of pentapeptide models of the sequences found near asparaginyl and glutaminyl residues in cytochrome c were measured. These rates were used to calculate a sequence‐determined half‐life for non‐deamidated cytochrome c. The sequence‐determined deamidation rates of the pentapeptide models were compared with the in vivo and in vitro deamidation rates of cytochrome c and the in vivo turnover rate of cytochrome c. Deamidation of the peptides during synthesis and purification was also measured. The implications of these measurements for deamidation as a biological molecular timer and deamidation during peptide synthesis are d

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02355.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

Affinity chromatography of α‐, β‐, ψ‐trypsins, chymotrypsin and elastase on trypsin inhibitor (bovine Kunitz inhibitor) coupled with Sepharose has shown that, despite the conformational similarity, elastase is not adsorbed in contrast to trypsins and chymotrypsin. This result might suggest that the specificity site is involved in the binding. On the other hand, because inactive DFP‐treated trypsin is not adsorbed, the catalytic site and especially Ser‐195 might also be necessary for the association.Chrymotrypsinogen is not adsorbed on the inhibitor‐Sepharose, but trypsinogen is retarded at pH 7.0 and the delay is increased at pH 8.1. The behaviour of trypsinogen on inhibitor‐Sepharose, in contrast to those of DIP‐trypsin and chymotrypsinogen, suggests that both catalytic and specificity sites are necessary for the binding and that these sites are partially pre‐exi

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02356.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY

摘要:

1Silk fibroin samples obtained by extraction of silk fibre with boiling, Na2CO3solution for different intervals of time were examined in 6M guanidine hydrochloride solution by gel filtration on agarose.2All the samples studied were heterogeneous. The weight‐average molecular weight of the samples estimated by gel filtration method was lower than that obtained by the Archibald ultracentrifuge method in 0.1 M KNO3solution.3This discrepancy was observed to be due to the dissociating effect of 6 M guanidine hydrochloride.4Sodium dodecyl sulfate and β‐mercaptoethanol also caused dissociation.5The thermal degradation of silk fibroin in Na2CO3solution followed a first order reaction kinetics.6Electrophoresis of the fibroins on polyacrylamide gels could not be performed since the protein remained at the top of the gel either due to precipitation of the protein or because of interaction with the gel. The experiments with buffer containing 6 M urea or 0.1% SDS also fa

ISSN:0367-8377    

DOI:10.1111/j.1399-3011.1974.tb02357.x

出版商:Blackwell Publishing Ltd    

年代:1974

数据来源: WILEY