Binding of 5,9-dimethyl dibenzo[c,g]carbazol, a potent hepatocarcinogen, to mouse hepatic cytosolic proteins

Abstract

5,9-Dimethyl dibenzo[c,g]carbazole (5,9-diMe DBC) is a powerful organ-specific liver carcinogen in mice. Its binding to liver cytosolic proteins has been studied in vivo and in vitro with the aid of a tritium-labelled sample. Only two classes of proteins fractionated on Sephadex G100 appear to be involved in this binding: one class of high mol. wt. proteins (>100 000) and another of around 45 000. The latter class contains all the glutathione-S-transferase activity (GST). The bound radioactivity has been determined after incubation in the presence or absence of microsomes. The in vivo binding has been investigated as a function of time. A highly significant covalent and noncovalent binding of 5,9-diMe DBC mostly to GST has been observed after metabolic activation.