Partial purification and some properties of gamma-glutamyl transpeptidase from human bile

1. Gamma-Glutamyl transpepetidase ((5-glutamyl)-peptide: amino acid 5-glutamyltransferase, EC 2.3.2.2) from human bile has been partially purified using protamine sulphate treatment, DEAE-cellulose chromatography and Sephadex G-200 filtration. The procedure resulted in 150-fold increase in specific acitivity with a 37% yield. 2. The partially purified enzyme showed a single zone of enzyme activity by polyacrylamide gel electrophoresis and eluted in the inner volume of Sephadex G-200. 3. The enzyme had a pH optimum of 8.1 and Km of 1.52 mM using gamma-glutamyl p-nitroanilide as substrate. 4. The effects of cations and different gamma-glutamyl acceptors on the activity of the enzyme are reported. 5. As bile gamma-glutamyl transpeptidase appears to be soluble in the absence of detergents, it is suggested that bile may prove to be a useful source for further studies of the kinetic properties and physiological role of human gamma-glutamyl transpeptidase.