Some Enzymatic Properties of Peptidyl Dipeptide Hydrolase

Abstract

Peptidyldipeptide hydrolase [angiotensin I-converting enzyme, EC 3.4.15.1] was inhibited by inorganic and organic phosphorus compounds tested, except for β-glycerophosphate, 5′-AMP, and 5′-ADP, at the reagent concentrations used. Orthophosphate and pyrophosphate nonspecifically inhibited the enzyme activity. The enzyme was also inhibited specifically by carboxylates. The degree of inhibition by aliphatic monocarboxylates increased in proportion to their chain length up to C₁₄. Aromatic and ω-phenylalkylcarboxylates also inhibited the enzyme activity. The enzyme was noncom-petitively inhibited by acetate, 3-phenylpropionate and laurate. The K₁'s for acetate, 3-phenylpropionate, and laurate were 60, 3.3, and 2.5 mM, respectively.