Kinetic studies of carboxypeptidase Y. II. Effects of substrate and product analogs on peptidase and esterase activities.

Reversible inhibition of the peptidase and esterase activities of CPase Y [EC 3.4.12.1] was investigated with substrate and product analogs known to be inhibitors or effectors of pancreatic carboxypeptidases A or B [EC 3.4.12.2 or 3]. L-Amino acids and NH2-blocked L-Amino acids showed competitive-type inhibition, whereas their D-enantiomers caused less inhibition than the L-enantiomers, and showed non-competitive or mixed-type inhibition. Some phenylalanine analogs, e.g. beta-phenylpropionic acid and t-cinnamic acid, were also reversible inhibitors of CPase Y. The type of these inhibitors and their K1 values were generally parallel for both the peptidase and esterase activities.