In vitro studies upon the release of γ-glutamyltransferase from human liver

Abstract Samples of human liver have been incubated in different fluids for up to 48 h and the released γ-glutamyltransferase studied by gel chromatography on Sephacryl S-300 and polyacrylamide gradient gel electrophoresis. When human liver is incubated in serum, most of the released enzyme is of high M r (greater than 1 000 000). Incubation in hepatic bile, or in a solution of glycochenodeoxycholate, results in the release of enzyme that is hydrophobic in nature and which reaggregates to a varying extent after the removal of bile salts. In contrast, incubation in saline, or in a solution of human albumin results in the release of a hydrophilic low M r (about 120 000) form of the enzyme. These observations are discussed in relation to possible mechanisms for the release of these multiple forms.