Kinetic studies of carboxypeptidase Y. I. Kinetic parameters for the hydrolysis of synthetic substrates.

Kinetic parameters for carboxypeptidase Y [EC 3.4.12.1], characterized as a nonspecific enzyme, are given for the hydrolysis of a series of acylated peptides, acylated amino acid esters, and amides. We confirmed that the enzyme released COOH-terminal proline and beta-alanine at an appreciable rate, as well as neutral amino acids with aromatic and aliphatic side chains at a very high speed. The rates of hydrolysis of ester and amide substrates were compatible with those produced by chymotrypsin [EC 3.4.21.1]. Stereospecificity was also demonstrated by the failure to hydrolyze peptide, ester, amide, and anilide substrates containing a D-amino acid. The effects of pH, solvents, and salt concentrations on the kinetic parameters of hydrolysis of peptide and ester substrates are also described.