Purification and Characterization of Serine Carboxypeptidases from Absidia zychae

概要

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Among 29 strains of zygomycetes screened for serine carboxypeptidases, Absidia zychae NRIC 1199 showed the highest enzyme production. Two serine carboxypeptidases, CPZ-1 and CPZ-2, were purified to a homogeneous state from an extract of koji culture of A. zychae NRIC 1199. Purified CPZ-1 and CPZ-2 showed similar properties except the isoelectric point (pI) ; The pI of CPZ-1 and CPZ-2 were 4.50 and 4.65, respectively. The molecular weights of the CPZ-1 and CPZ-2 were 48,000 by SDS-PAGE and gel filtration. Among the proteinase inhibitors tested, phenylmethylsulfonyl fluoride and monoiodoacetic acid strongly inhibited the enzyme activity. The optimum pHs of CPZ-1 and CPZ-2 were 4.2 towards Z-Glu-Tyr. It is shown that the substrate specificities of CPZ-1 and CPZ-2 were dependent on the presence of bulky amino acid residues in the penultimate position (P_1) for the small Z-peptides. However, in spite of the presence of Gly, Asp, Arg, or Pro in the P_1 position, oligopeptides were hydrolyzed rapidly. CPZ-1 and CPZ-2 had not only carboxypeptidase but also carboxyamidase and amidase activities, and acted preferentially as a carboxyamidase for C-terminal amidated peptides. The hydrophobicity of P_2 and P_3 positions and the bulkiness of P_1 and P'_1 positions of the substrate may be important for carboxyamidase and amidase activities.
社団法人日本農芸化学会の論文
1993-04-23