title: Epoxidation of C18 unsaturated fatty acids by cytochromes P4502C2 and P4502CAA.
abstract: The regioselective epoxidation of oleic, linoleic, alpha-linolenic, and gamma-linolenic acid by cytochromes P4502CAA and P4502C2 was characterized. Epoxide metabolites for all fatty acids were resolved by normal phase HPLC and identified by gas chromatography and mass spectrometry. Both isoforms epoxidized the single double bond in oleic acid and both double bonds in linoleic acid. The ratio of the two epoxides produced with linoleic acid (1.6:1 for the 12,13- and 9,10-epoxides) was similar for both enzymes. When alpha-linolenic acid was the substrate, all three epoxides were produced in about equal ratios with both enzymes. In contrast for the omega-6 fatty acid, gamma-linolenic acid, both enzymes produced only the 9,10- and 12,13-epoxides. Furthermore, the ratio of the metabolites produced by each enzyme was significantly different. The ratios of 12,13-epoxide to 9,10-epoxide for gamma-linolenic were 11.0 +/- 0.19 and 5.8 +/- 1.2 for P4502CAA and P4502C2, respectively. These results suggest that there may be subtle differences in the structure of 2C2 and 2CAA and also indicate that P450 may be important in the generation of potentially active epoxide metabolites of unsaturated fatty acids other than arachidonic acid.
authors.affiliation: Department of Pharmacology, Oregon Health Sciences University, Portland 97201, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Laethem
authors.forename: M
authors.initials: M
authors.lastname: Balazy
authors.forename: D R
authors.initials: DR
authors.lastname: Koop
mesh_terms: D000818:Animals; D016718:Arachidonic Acid; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D000090762:Cytochrome P-450 CYP2J2; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology*; D010105:Oxygenases / Q000378:metabolism*; D011817:Rabbits
chemical_list: D005231:Fatty Acids, Unsaturated; D016718:Arachidonic Acid; D003577:Cytochrome P-450 Enzyme System; C084930:cytochrome P-450 2C2; D010105:Oxygenases; D000090762:Cytochrome P-450 CYP2J2