Mechanisms for activation and inhibition of carboxypeptidase A catalyzed hydrolyses of peptides and esters.

3,3-Diphenylpropanoate (DPP) activates the carboxypeptidase A catalyzed hydrolysis of benzoylglycyl-L-phenylalanine (BzGly-L-Phe) (Ka = 2.1 x 10 (-3) M) and inhibits ester hydrolysis uncompetitively (K1 =2.1 X 10 (-3) M). A common modifier binding site located adjacent to the peptide and ester substrate binding sites is proposed. The forms of the pathways proposed for activation and inhibition are remarkably similar.