In enzymology, a Microsomal Epoxide Hydrolase (EC 22.214.171.124) is an enzyme that catalyzes the chemical reaction:
cis-stilbene oxide + H2O (+)-(1R,2R)-1,2-diphenylethane-1,2-diol
Thus, the two substrates of this enzyme are cis-stilbene oxide and H2O, whereas its product is (+)-(1R,2R)-1,2-diphenylethane-1,2-diol.
This enzyme belongs to the family of hydrolases, specifically those acting on ether bonds (ether hydrolases). The systematic name of this enzyme class is cis-stilbene-oxide hydrolase. Other names in common use include epoxide hydratase (ambiguous), microsomal epoxide hydratase (ambiguous), epoxide hydrase, microsomal epoxide hydrase, arene-oxide hydratase (ambiguous), benzo[a]pyrene-4,5-oxide hydratase, benzo(a)pyrene-4,5-epoxide hydratase, aryl epoxide hydrase (ambiguous), cis-epoxide hydrolase, and mEH. This enzyme participates in metabolism of xenobiotics by cytochrome p450.
It should also be noted that this class of enzymes plays a role in the uptake of bile salts within the large intestine. It functions as a Na+ dependent transporter.