[Comparative characteristics of microsomal epoxide hydrolase in the rat liver and small intestine mucosa]

Activity of epoxide hydrolase was studied in microsomes of rat liver and small intestinal mucosa with styrene oxide as substrate using high performance liquid chromatography. Specific activity of epoxide hydrolase in microsomes from small intestine constituted 5-10% of the activity in liver microsomes. Both these enzymes had similar kinetic parameters, the same pH optimum around pH 8.7; their activity was altered only slightly in presence of anionic detergents. The enzyme activity was increased in liver and small intestine after administration of benzyl, trans-stilbene oxide, 2-acetamidofluorene and butylated hydroxytoluene. 1,2-epoxy-3,3,3-trichloropropane and 2-brom-4-nitroacetophenon inhibited similarly epoxide hydrolase in hepatic and intestinal microsomes. Cyclohexene oxide inhibited both these enzymes by the non-competitive type, exhibiting the higher affinity to liver epoxide hydrolase.