発芽ダイズ種子カルボキシペプチダーゼ(第1報)2種のカルボキシペプチダーゼの精製と性質

概要

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Two kinds of carboxypeptidases, CPase S_a and CPase S_b, were separated from germinating soybeans (Glycine Max. AKIYOSHI) in a highly purified form. The enzymes liberated neutral, acidic, and basic amino acids including proline from the C-termini of N-substituted dipeptides at varying rates. Of the substrates tested, Z-Gly-Pro, Z-Pro-Pro, Z-Gin-Pro, Bz-Gly-Lys, and Bz-Gly-Arg were hydrolyzed very slowly. The specific activities of purified CPase S_a and S_b were 0.11 and 3.68 units/mg of protein, respectively, for Z-Glu-Phe. The enzyme also released C-terminal amino acid residues from peptide and protein substrates. They possessed weak esterase activity, but were free of endopeptidase and aminopeptidase activities. They had a pH optimum at 5.5 for Z-Glu-Phe. CPase S_b was strongly inhibited by diisopropylfluorophosphate (DFP) and HgCl_2,whereas CPase S_a was only partially inhibited. Other metal ions, anions, ethylenediaminetetra-acetic acid (EDTA), o-phenanthroline, N-ethylmaleimide (NEM), p-chloromercuribenzoic acid (PCMB), dithiothreitol (DTT). and monoiodoacetic acid (MIA) showed no significant effect on the enzymic activity. The molecular weight of CPase S_a was 99000 (s_<20,w>=6.9S, D_<20,w>=6.4×10^<-7>cm^2/sec) and that of CPase S_b, 106000 (s_<20,w>=6.1S, D_<20,w>=5.4×10^<-7>cm^2/sec).
公益社団法人日本薬学会の論文
1976-05-25