Separation of hydrophobic and hydrophilic forms of γ-glutamyltransferase from human serum by hydrophobic chromatography on phenyl-Sepharose CL-4B: studies on normal sera and sera of patients with liver disease

Abstract

A new method is described for the separation of hydrophobic and hydrophilic forms of γ-glutamyltransferase (GGT) present in human serum using hydrophobic chromatography on phenyl-Sepharose CL-4B columns. The analysis of sera of 30 normal healthy people showed that 71.49 ± 8.73% (mean ± SD) of the GGT was in the hydrophilic form. In sera from 52 patients with various liver diseases the major part of the total enzyme was hydrophobic GGT, contributing 67.38 ± 13.8% of the total GGT activity. Elevated total serum GGT and a hydrophobic to hydrophilic ratio of more than one helped in diagnosing hepatobiliary disease in 51 of 52 patients. Papain digestion of serum converted hydrophobic to hydrophilic GGT, which was similar to soluble form of liver GGT. The results are discussed in relation to the proposed mechanisms of release of GGT from the liver to the circulation.