ACTION OF SERINE CARBOXYPEPTIDASE FROM PAECILOMYCES-CARNEUS ON OLIGOPEPTIDES CONTAINING CARBOXY-TERMINALLY AMIDATED PEPTIDES

Paecilomyces carneus carboxypeptidase sequentially liberated amino aci ds from the carboxy-terminus of neurotensin, angiotensin I, bradykinin , and delta sleep-inducing peptide, indicating that the sequential hyd rolysis of peptides was limited by the occurrence of intermediates wit h the structure of -Gly-X (X = L-amino acid), -Pro-X, -X-Gly, and -X-P ro. The enzyme had carboxyamidase and/or amidase activities for the ca rboxy-terminally amidated peptides. The enzyme essentially acted as a carboxyamidase for the long carboxy-terminally amidated peptides; an a midase became dominant for the substrates in the presence of bulky ami no acids such as Arg, Met, Leu, and Phe in the penultimate (P-1) and P -2 positions, corresponding with the S-1 and S-2 sites of the enzyme, and the P-3 position of carboxy-terminally amidated peptides played a significant role in the action as a carboxyamidase or a amidase.