AN ENZYME CATALYSING THE CONJUGATION OF EPOXIDES WITH GLUTATHIONE.

1. Liver supernatant preparations from rats and ferrets catalyse the conjugation of some epoxides with glutathione. The enzyme involved might be called ;glutathione S-epoxidetransferase', as it is different from glutathione S-aryltransferase, the enzyme catalysing the conjugation of 1,2-dichloro-4-nitrobenzene, 4-nitro-pyridine N-oxide and other cyclic compounds with glutathione and from the enzyme catalysing the conjugation of iodomethane and glutathione. 2. The enzyme does not catalyse the reaction with cysteine. It is not inactivated by dialysis but is unstable at pH 5.0. 3. The role of the enzyme in metabolism of foreign compounds is discussed.