title: NAD(P)H-dependent reduction of 12-ketoeicosatetraenoic acid to 12(R)- and 12(S)-hydroxyeicosatetraenoic acid by rat liver microsomes.
abstract: The possibility that 12-keto-5,8,10,14 eicosatetraenoic acid (12-KETE) could be used as substrate by reductase(s) to generate 12-hydroxyeicosatetraenoic acid (12-HETE) was investigated using rat liver microsomes as a source of enzyme activity. Microsomes catalyzed the time-dependent reduction of 12-KETE to 12-HETE in a reaction that required NAD(P)H. The maximal specific activity of 12-HETE formation was 1.7 nmol/min/mg of protein in the presence of NADH. The reaction could not be detected in the absence of cofactor or by using heat inactivated microsomes. The identity of the 12-HETE product was established by U.V. spectroscopy and co-elution with 12-HETE in two different systems of RP-HPLC. Resolution of the methyl esters of reaction products by chromatography on chiral columns also indicated that the reduction of 12-KETE with either NADPH or NADH generated a mixture of 12(S)- and 12(R)-HETE in a ratio of about 2:1. The results demonstrate the presence of a 12-KETE reductase activity in rat liver microsomes which can form both the R and S isomers of 12-HETE.
authors.affiliation: Merck Frosst Canada Inc., Pointe Claire-Dorval, Québec, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Falgueyret
authors.forename: Y
authors.initials: Y
authors.lastname: Leblanc
authors.forename: J
authors.initials: J
authors.lastname: Rokach
authors.forename: D
authors.initials: D
authors.lastname: Riendeau
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D001095:Arachidonic Acids / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000096:biosynthesis*; D066298:In Vitro Techniques; D008862:Microsomes, Liver / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology*; D010084:Oxidation-Reduction; D051381:Rats
chemical_list: C054994:12-keto-5,8,11,13-eicosatetraenoic acid; D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D009249:NADP; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid