title: Inhibition of carboxypeptidase A catalyzed peptide hydrolysis by 3-phenylpropanoate at activating and nonactivating substrate concentrations.
abstract: The carboxypeptidase A catalyzed hydrolyses of five structurally related dipeptide substrates in the presence of the inhibitor 3-phenylpropanoate have been studied. At nonactivating substrate concentrations, 3-phenylpropanoate is a mixed inhibitor of carbobenzoxyglycyl-L-phenylalanine hydrolysis and a noncompetitive inhibitor of the hydrolyses of benzoylglycyl-L-phenylalanine, cinnamoylglycyl-L-phenylalanine, hydrocinnamoylglycyl-L-phenylalanine, and acetylglycyl-L-phenylalanine. When carbobenzoxyglycyl-L-phenylalanine and benzoylglycyl-L-phenylalanine exhibit substrate activation, inhibition by 3-phenylpropanoate is mixed but appears to be mostly competitive. Proposed here is a site for the binding of 3-phenylpropanoate along with a kinetic mechanism consistent with these data.
mesh_terms: D002268:Carboxypeptidases / Q000378:metabolism*; D004789:Enzyme Activation; D007700:Kinetics; D008433:Mathematics; D010666:Phenylpropionates / Q000494:pharmacology*; D013379:Substrate Specificity
chemical_list: D010666:Phenylpropionates; D002268:Carboxypeptidases