Characterization of the principal human prostatic acid phosphatase isoenzyme, purified by affinity chromatography and isoelectric focusing. Part II.

The principal enzyme of human prostatic acid phosphatase [orthophosphoric monoester phosphohydrolase (acid optimum), EC 3.1.3.2], which had been highly purified by affinity chromatography, isoelectric focusing, and gel filtrations, was shown to be homogeneous at pH 5.0 by sedimentation equilibrium analysis. The amino acid composition was determined and the sedimentation coefficient of the native molecule measured. The relative molecular mass was 89,000 at pH 5.0, as measured by analytical ultracentrifugation. The Km-value of the enzyme for p-nitrophenyl phosphate as substrate is 1.8-10(-4) mol/liter. I also examined substrate speificity, different inhibitors, and the effects of pH, temperature, and serum on the enzyme activity.