The inhibition of seminal acid phosphatase by macromolecular compounds

Abstract

The hydrolysis of monophenyl phosphate by unpurified human seminal acid phosphatase has been investigated. The optimum pH was found to lie between 5.4 and 5.7 and was not influenced by the substrate concentration. The Michaelis constant was estimated at several pH values. At the optimum pH a Km value of 0.18 m[image] was repeatedly found. High substrate concentrations did not inhibit the enzyme activity. Polyestradiol phosphate was a powerful, non-competitive inhibitor of seminal acid phosphatase. The inhibitory effect was strongest on the acid side of the pH optimum. The inhibition could be reversed by small amounts of protamine sulfate. The enzyme was also inhibited by polymeric phosphates of phloretin, phlorhizin and hesperidin. The inhibition by polyphloretin phosphate was non-competitive. The trypanocide suramine proved to be a non-competitive inhibitor of seminal acid phosphatase.