Purification and properties of human liver peptidase

The peptidase from human liver was purified using L-Leu-L-Leu as a substrate, in adapted purification techniques including treatment with n-butanol, acetone precipitation, ammonium sulfate fractionation, DEAE-cellulose chromatography, Sephadex G-150 gel filtration and CM-cellulose chromatography. The purified enzyme exhibited homogeneity in disc electrophoresis. The molecular weight of the enzyme was estimated to be 130 000 by Sephadex G-200 gel filtration. The isoelectric point of the enzyme was found to be pH 5.6. The enzyme was activated by Mn2+ and inhibited by o-phenanthroline. L-Leu-L-Leu and L-Phe were hydrolyzed effectively by the peptidase. By electrophoresis on Cellogel, the electrophoretic mobility of purified enzyme was same as that of the peptidase in serum of patients with hepatic disease.