Evidence for Several Hepatic Proteins Related to Microsomal Epoxide Hydrolase

Epoxide hydrolases catalyze the conversion of epoxides, some of which have been shown to be carcinogenic, to dihydrodiols (Guenthner and Oesch 1981). At least three forms of epoxide hydrolases exist in rats, two of which, namely mEHb and mEHch, are associated mainly with the microsomal fraction (Oesch et al 1984; Levin et al 1983) whereas one form namely cEH is found to a large extent in the cytosolic fraction (Gill and Hammock 1981). These three forms differ in their immunological and catalytic properties quite considerably (Guenthner et al 1981). In the case of mEHb the existence of several closely related isoenzymes with an identical apparent subunit molecular weight (Mrs) of 50,000 was …