Oxidation and keto reduction of 12-hydroxy-5,8,10,14-eicosatetraenoic acids in bovine corneal epithelial microsomes

Satoru Yamamoto, Motonubu Nishimura, Michael S. Conners, Robert A. Stoltz, J R Falck, Kamlesh Chauhan, Michal Laniado-Schwartzman

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

The R and S enantiomers of 12-hydroxyeicosatetraenoic acid (12-HETE) exhibit different biological activities. Although they appear to be produced by different enzymatic pathways, cytochrome P-450 monooxygenase and lipoxygenase, respectively, they display similar metabolism in both corneal epithelium and neutrophils. In corneal epithelial microsomes, both enantiomers are subject to oxidation and keto reduction reactions to form the dihydro metabolite, 12-hydroxy-5,8,14-eicosatrienoic acid (12-HETrE), via a keto intermediate. The apparent Km for the formation of 12-HETrE was 17.9 and 20 μM for 12(R)-HETE and 12(S)-HETE, respectively, and the apparent Vmax of the reaction was 17.4 and 8.2 pmol/mg per min, respectively. Chiral analysis of the dihydro metabolite demonstrated a product enantiospecificty. Arachidonic acid, 12(R)-HETE, 12(S)-HETE and the intermediate of this reaction, 12-oxo-ETrE, were metabolized predominantly to 12(R)-HETrE in a ratio [12(R)-HETrE: 12(S)-HETrE] of 7.3:1, 4.3:1, 1.5:1 and 2.3:1, respectively. 12(R)-HETrE is a potent vasodilator, chemotactic and angiogenic factor whose synthesis is induced in inflamed tissues; 12(S)HETrE is devoid of these properties. 12(R)-HETE, derived from NADPH-dependent cytochrome P-450 monooxygenases, and 12(S)-HETE, derived from 12-lipoxygenase, may both play an important role in regulating the inflammatory response by serving as substrates for the local synthesis of 12(R)-HETrE.

Original languageEnglish (US)
Pages (from-to)217-225
Number of pages9
JournalBiochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
Volume1210
Issue number2
DOIs
StatePublished - Jan 3 1994

Keywords

  • 12-Hydroxyeicosatetraenoic acid
  • 12-Hydroxyeicosatrienoic acid
  • Arachidonic acid
  • Cytochrome P-450
  • Lipoxygenase

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Endocrinology

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