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5126592 
Journal Article 
Epoxide hydrase activity in liver nuclei: hydration of benzo[a]pyrene-4,5-oxide and styrene oxide 
Bornstein, WA; Chuang, H; Bresnick, E; Mukhtar, H; Bend, JR 
1978 
Yes 
Chemico-Biological Interactions
ISSN: 0009-2797
EISSN: 1872-7786 
21 
2-3 
343-346 
English 
679405 
WOS:A1978FN07100018 
The effects of benzo(a)pyrene-4,5-oxide (37574473) (BP-4,5-oxide) and styrene-oxide (96093) on epoxide hydrase activity in liver nuclei were studied. Purified liver nuclei from Sprague-Dawley-rats were incubated with the test substances by high pressure liquid chromatography (HPLC) assay and by radioactive assay. In some tests, an oxide of a polycyclic hydrocarbon was used as a substrate. Trans diol formation was determined as a function of time and nuclear protein. In the HPLC assay using BP-4,5-oxide, enzyme activity was directly proportional to nuclear protein up to a concentration of 10 milligrams (mg) and up to 20 minutes of incubation. In the radioactive assay, linear relationships occurred for styrene-oxide up to 3mg nuclear protein and 10 minutes of incubation and for BP-4,5-oxide up to 1mg protein and 15 minutes of incubation. Epoxide hydrase activity of purified liver nuclei by either assay method was 0.33 to 0.35 nanomoles per minute (nmol/min) per mg protein with BP-4,5-oxide and 0.41nmol/min/mg protein with styrene-oxide. The authors conclude that the liver nucleus not only is a prime target for the action of polycyclic hydrocarbons but also may be the mechanism for metabolic activation of these substances for mutagenesis, teratogenesis or carcinogenesis.