Hematin-Assisted Intramolecular Oxygen Transfer Mechanism Is Involved in the Formation of 8-Hydroxy-11,12-epoxyeicosa-5,9,14-trienoic Acid (8H-11, 12-EPETE) from 12-HPETE
We recently described the isolation and structure of two hydroxyepoxides formed from 12-HPETE by an enzyme system present in rat lung (Pace-Asciak et al.,1983a). These were shown to be 8-hydroxy-ll,12-epoxy (8H-11,12-EPETE) and 10-hydroxy-ll,12-epoxy (1 OH-11,12-EPETE) eicosatrienoic acid. Evidence was presented to show that both oxygen atoms in the hydroxyepoxides were derived from molecular oxygen (Pace-Asciak et al., 1983a). Also, when [18O]oxygenated 12-HPETE was incubated with this enzyme preparation, 18O atoms were found in both the hydroxyl and the epoxide groups, suggesting that the hydroxyl group at carbon 8 and carbon 10 was derived from the hydroperoxide of 12-HPETE (Pace-Asciak et al., 1983a). However, whether the terminal hydroxyl group of the hydroperoxide of 12-HPETE was transferred via an inter- or intramolecular mechanism was not determined. The present chapter reports evidence with a mixture of [16O]- and [18O]-labeled 12-HPETE to show a unique intramolecular rearrangement of 12-HPETE into the hydroxyepoxides catalyzed by bovine hematin in a protein-free environment as well as by a rat lung cytosol fraction.
KeywordsElectron Paramagnetic Resonance Octadecadienoic Acid Ammonium Sulfate Fraction Eicosatrienoic Acid Epoxy Alcohol
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