Effect of sulfonates on the esterase activity of carboxypeptidase A.

The effects of sulfonates on the carboxypeptidase A catalyzed hydrolysis of the ester substrate benzoylglycyl-L-phenyllactate were determined. The modifiers examined were benzenesulfonate, p-toluenesulfonate, 2-phenylethane-sulfonate, methanesulfonate, ethanesulfonate, propanesulfonate, butanesulfonate, pentanesulfonate, hexanesulfonate, heptanesulfonate, and 2,2-dimethyl-2-silapentane-5-sulfonate. Sulfonate activators of peptide hydrolysis were inhibitors of esterase activity. Of the sulfonates studied, 2,2-dimethyl-2-silapentane-5-sulfonate was the most effective inhibitor. 2-Phenylethanesulfonate, hexanesulfonate, heptanesulfonate, and 2,2-dimethyl-2-silapentane-5-sulfonate exhibited uncompetitive inhibition. The remaining sulfonates either did not inhibit or the inhibition was too weak to properly characterize.