Purification and Some Properties of Glutathione-S-Epoxide Transferase from Guinea Pig Liver

Abstract

Glutathione-S-epoxide transferase has been purified from guinea pig liver in a homogeneous form having a sedimentation coefficient, s_{20, w} of 3.8S, and a molecular weight of 46, 000, and dissociable into subunits with a molecular weight of 25, 000. The activities with four substrates, styrene oxide, naphthalene oxide, iodomethane, and p-nitrobenzyl chloride, were all copurified during purification of the enzyme from 100, 000×g supernatant of guinea pig liver. However, kinetic data suggest different mechanisms for the glutathione conjugating reaction with iodomethane and p-nitrobenzyl chloride. The view that the epoxide transferase does not distinguish between simple epoxides and arene oxides has been confirmed with the guinea pig liver enzyme.