Characterization of the cytosolic epoxide hydrolase-catalyzed hydration products from 9,10: 12,13-diepoxy stearic esters

Jaffar Nourooz-Zadeh, Tamon Uematsu, Babak Borhan, Mark J. Kurth, Bruce D. Hammock

Research output: Contribution to journalArticle

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Abstract

In a previous report we hypothesized that diepoxy fatty methylesters are metabolized to tetraols and/or tetrahydrofurandiols through an epoxydiol intermediate. In this study, p-nitrophenyldiepoxystearate was incubated with affinity-purified liver cytosolic epoxide hydrolase and product formation was monitored by reverse phase HPLC. The diepoxystearate was converted to the corresponding 9,10,12,13-tetraol using a concentrated enzyme (≥100 μg/ml). When lower concentration of the enzyme was used, simultaneous elevation of 9,10-epoxy-12,13-dihydroxy and 12,13-epoxy-9,10-dihydroxystearate along with disappearance of tetraol was observed. The epoxydiols were intermediates which could be isolated and cyclized quantitatively to form two chromatographically distinct tetrahydrofurandiols (A with a low Rf value and B with a high Rf value on TLC). Gas Chromatographic analysis on a cyclodex-β capillary column revealed that each compound was composed of two different isomers. The structure of these isomers was 9(12)-oxy-10,13-dihydroxystearate and 10(13)-oxy-9,12-dihydroxystearate using mass spectrometry. Stereochemistry of the aliphatic chain across the tetrahydrofuran moiety was determined by nuclear Overhauser effect spectroscopy. Chemically and enzymatically generated tetrahydrofurandiols had similar retention time on GC and HPLC, and identical mass spectra using the electron impact mode.

Original languageEnglish (US)
Pages (from-to)675-685
Number of pages11
JournalArchives of Biochemistry and Biophysics
Volume294
Issue number2
DOIs
StatePublished - May 1 1992

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Epoxide Hydrolases
Isomers
Hydration
Esters
High Pressure Liquid Chromatography
Stereochemistry
Enzymes
Gas chromatography
Gas Chromatography
Liver
Mass spectrometry
Mass Spectrometry
Spectrum Analysis
Spectroscopy
Electrons
tetrahydrofuran

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology

Cite this

Characterization of the cytosolic epoxide hydrolase-catalyzed hydration products from 9,10 : 12,13-diepoxy stearic esters. / Nourooz-Zadeh, Jaffar; Uematsu, Tamon; Borhan, Babak; Kurth, Mark J.; Hammock, Bruce D.

In: Archives of Biochemistry and Biophysics, Vol. 294, No. 2, 01.05.1992, p. 675-685.

Research output: Contribution to journalArticle

Nourooz-Zadeh, Jaffar ; Uematsu, Tamon ; Borhan, Babak ; Kurth, Mark J. ; Hammock, Bruce D. / Characterization of the cytosolic epoxide hydrolase-catalyzed hydration products from 9,10 : 12,13-diepoxy stearic esters. In: Archives of Biochemistry and Biophysics. 1992 ; Vol. 294, No. 2. pp. 675-685.
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