Epoxide hydrolase in human placenta at different stages of pregnancy.
The epoxide hydrolase activity towards styrene-7,8-oxide was investigated in the microsomal fraction of 18 human placentas from the midtrimester and the term of pregnancy. The enzymatic activity was 0.40 +/- 0.03 nmol/min/mg microsomal protein. No relation was found between gestational age and the rate of styrene oxide hydration. The kinetics of the enzyme were studied in 3 placentas. Biphasic kinetics were observed in each of the tissue specimens. The enzyme was inhibited both by 1,1,1-trichloropropene-2,3-oxide (0.25 mM) and benzo(a)pyrene-4,5-oxide (0.2 mM) which had similar inhibiting potency.
D000818:Animals; D001580:Benzopyrenes / Q000494:pharmacology; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004851:Epoxide Hydrolases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004852:Epoxy Compounds / Q000378:metabolism*; D004988:Ethers, Cyclic / Q000378:metabolism*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007700:Kinetics; D008099:Liver / Q000196:embryology / Q000201:enzymology / Q000378:metabolism; D000432:Methanol / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology* / Q000378:metabolism; D010920:Placenta / Q000201:enzymology* / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D014239:Trichloroepoxypropane / Q000494:pharmacology
D001580:Benzopyrenes; D004852:Epoxy Compounds; D004988:Ethers, Cyclic; D014239:Trichloroepoxypropane; C006707:benzo(a)pyrene 4,5-epoxide; C013690:styrene oxide; D004851:Epoxide Hydrolases; C022686:styrene oxide hydratase; D000432:Methanol; D004121:Dimethyl Sulfoxide