Effect of purified rat and hamster hepatic glutathione S-transferases on the microsome mediated binding of aflatoxin B1 to DNA.

Rat and hamster liver cytosolic glutathione (GSH) S-transferases purified by GSH-affinity chromatography have been examined for their effects on the microsome mediated binding of aflatoxin B1 (AFB1) to DNA and on the conjugation of AFB1-2,3-epoxide with GSH. Like previous studies with cytosolic preparations (Raj et al. (1984) Carcinogenesis 5, 879), our present study with purified GSH S-transferases showed 2-3-fold more inhibitory activity of AFB1-DNA binding with hamster than that with the rat. Concomitant with the inhibition of AFB1-DNA binding, increase in AFB1-GSH conjugation occurred. Subunit compositions of GSH S-transferases indicate preponderance of Yb and Ya subunits in the hamster and rat, respectively. The role of GSH S-transferases in modulating AFB1-DNA binding and AFB1 induced hepatocarcinogenesis is discussed.