A new procedure for the visualization of multiple forms of gamma-glutamyl transferase (GGT). Results in normals, patients receiving enzyme-inducing drugs and patients having liver parenchymal lesions.

The activity of gamma-glutamyl transferase (GGT, EC 2.3.2.2) in sera of 68 healthy individuals, of 38 patients receiving anti-epileptic drugs, and of 27 patients having liver parenchymal lesions, was visualized after electrophoresis on cellulose-acetate gel using the substrate gamma-L-glutamyl-p-nitroanilide as a new colour reagent. The liberated p-nitroaniline was converted in situ into a lilac-coloured product using the Bratton-Marshall reaction. In most samples two bands were demonstrated, one located between albumin and alpha1-globulin, called GGT 1, the other located in the alpha2-globulin region, GGT 2. In a few samples a third band, GGT 3, with far less activity than the other bands, occurred in the beta-globulin region. When it occurred, an increase in total GGT activity was mainly due to an increase of GGT-1 activity. The possible role of the determination of GGT-1 activity as a monitor of microsomal enzyme induction is discussed.