Purification and Properties of Gamma-Glutamyl Transpeptidase from the Tissue of Human Benign Prostatic Hypertrophy

Abstract

The enzyme of gamma-glutamyl transpeptidase was purified to homogeneity from the tissue of human benign prostatic hypertrophy and its enzyme properties were studied. The enzyme activity was detected mainly in the luminal border of the epithelium lining ducts by histochemical staining. The enzyme was purified 759-fold that of the crude extract. The specific activity of the purified enzyme was 79,900mU/mg protein. The following enzyme properties were obtained: Michaelis constant of the enzyme was 0.83mmol/1. The molecular weight was 72kDa, consisting of two subunits, 45kDa and 27kDa. The isoelectric point of the enzyme was 8.5. The optimum pH ranged from 8.2 to 8.5. By Concanavalin A-sepharose affinity chromatography, more than 60% of the enzyme activity was eluted in the weakly bound fraction, suggesting biantennary complex sugar chain was the major type among the asparagine-linked sugar-chains of the enzyme.