Purification of gamma-glutamyltranspeptidase (gamma-GTP) from human hepatocellular carcinoma (HCC), and comparison of gamma-GTP with the enzyme from human kidney.

In order to elucidate the characteristics of novel gamma-GTP, which was reported in our previous publications to be specific to sera of HCC, gamma-GTP was purified from HCC tissues, and its physicochemical and immunologic properties were compared with those of the normal adult kidney enzyme. The enzyme from HCC tissue and from normal kidney were found to be similar or identical with respect to the Km value for substrate, optimal pH, thermostability, effect of various amino acids as acceptors, behavior to cations or ethylendiaminetetraacetate, and immunologic properties. However, the HCC tissue enzyme was distinguishable from the normal kidney enzyme with respect to molecular weight, electrophoretic mobility before and after neuraminidase treatment, Con-A-affinity, sensitivity to neuraminidase, and isoelectrophoretic point. These results support the conceivability that novel gamma-GTP in the sera of HCC patients is largely due to structural differences in the carbohydrate moieties.