Epoxide hydrolase activities in the microsomes and the soluble fraction from Vicia sativa seedlings

F. Pinot, H. Bosch, J. P. Salaun, F. Durst, C. Mioskowski, B. D. Hammock

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Epoxide hydrolases (EC 3.3.2.3) in the microsomal and soluble fractions of 4 d old Vicia sativa seedlings hydrolyze 9,10-epoxystearic acid to 9,10-dihydroxystearic acid. No alteration of epoxide hydrolase activity was observed after treatment of the seedlings with 8 mM phenobarbital or 0.5 mM 2,4-dichlorophenoxyacetic acid compared to control plants. Treatment with 1 mM clofibrate decreased the activity in the microsomes by 37%, but had no effect on the activity in the soluble fraction. Four different inhibitors of mammalian epoxide hydrolases were tested. Preincubation of either subcellular fraction with 4-fluorochalcone oxide had no effect. Weak inhibition (25% in microsomes and 16% in the soluble fraction) was observed following preincubation with 1,1,1-trichloropropene-2,3-oxide. After preincubation with (2S,3S)-(-)-3-(4-nitrophenyl)-glycidol, we measured a 45% decrease in soluble epoxide hydrolase activity whereas no change was observed in the microsomal epoxide hydrolase activity. The 2R, 3R enantiomer did not affect activity in either fraction. Lowering the pH from 9 to 7.4 stimulated the activity by 366% in the cytosol but only by 72% in the microsomes. After incubation of a racemic mixture of 9,10-epoxystearic acid with the microsomal fraction, the chirality of the residual epoxide was 69/31 in favor of the 9S, 10R enantiomer. We determined K(m) of 5.2±0.5 and 2.5±0.4 μM and V(max(observed)) of 198±4.7 and 404±10 pmol min-1 mg-1 for the 9S, 10R and 9R, 10S enantiomers, respectively.

Original languageEnglish (US)
Pages (from-to)103-110
Number of pages8
JournalPlant Physiology and Biochemistry
Volume35
Issue number2
StatePublished - 1997

Keywords

  • cutin
  • Epoxide hydrolase
  • induction
  • inhibition
  • plant
  • Vicia sativa
  • xenobiotic

ASJC Scopus subject areas

  • Plant Science
  • Biochemistry
  • Biotechnology

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    Pinot, F., Bosch, H., Salaun, J. P., Durst, F., Mioskowski, C., & Hammock, B. D. (1997). Epoxide hydrolase activities in the microsomes and the soluble fraction from Vicia sativa seedlings. Plant Physiology and Biochemistry, 35(2), 103-110.