title: Antioxidative function and substrate specificity of NAD(P)H-dependent alkenal/one oxidoreductase. A new role for leukotriene B4 12-hydroxydehydrogenase/15-oxoprostaglandin 13-reductase.
abstract: There are several known routes for the metabolic detoxication of alpha,beta-unsaturated aldehydes and ketones, including conjugation to glutathione and reduction and oxidation of the aldehyde to an alcohol and a carboxylic acid, respectively. In this study, we describe a fourth class of detoxication that involves the reduction of the alpha,beta-carbon=carbon double bond to a single bond. This reaction is catalyzed by NAD(P)H-dependent alkenal/one oxidoreductase (AO), an enzyme heretofore known as leukotriene B4 12-hydroxydehydrogenase, 15-oxoprostaglandin 13-reductase, and dithiolethione-inducible gene-1. AO is shown to effectively reduce cytotoxic lipid peroxidation products such as 4-hydroxy-2-nonenal (HNE) (k(cat) = 4.0 x 10(3) min(-1); k(cat)/K(m) = 3.3 x 10(7) min(-1) M(-1)) and acrolein (k(cat) = 2.2 x 10(2) min(-1); k(cat)/K(m) = 1.5 x 10(6) min(-1) M(-1)) and common industrial compounds such as ethyl vinyl ketone (k(cat) = 9.6 x 10(3) min(-1); k(cat)/K(m) = 8.8 x 10(7) min(-1) M(-1)) and 15-oxoprostaglandin E1 (k(cat) = 2.4 x 10(3) min(-1); k(cat)/K(m) = 2.4 x 10(9) min(-1) M(-1)). Furthermore, transfection of human embryonic kidney cells with a rat liver AO expression vector protected these cells from challenge with HNE. The concentration of HNE at which 50% of the cells were killed after 24 h increased from approximately 15 microM in control cells to approximately 70 microM in AO-transfected cells. Overexpression of AO also completely abolished protein alkylation by HNE at all concentrations tested (up to 30 microM). Thus, we describe a novel antioxidative activity of a previously characterized bioactive lipid-metabolizing enzyme that could prove to be therapeutically or prophylactically useful due to its high catalytic rate and inducibility.
authors.affiliation: Department of Pharmacology and Molecular Sciences, Johns Hopkins School of Medicine, Baltimore, Maryland 21205, USA.
authors.forename: R A
authors.initials: RA
authors.lastname: Dick
authors.forename: M K
authors.initials: MK
authors.lastname: Kwak
authors.forename: T R
authors.initials: TR
authors.lastname: Sutter
authors.forename: T W
authors.initials: TW
authors.lastname: Kensler
mesh_terms: D011452:15-Oxoprostaglandin 13-Reductase / Q000096:biosynthesis / Q000378:metabolism*; D000429:Alcohol Oxidoreductases / Q000096:biosynthesis / Q000378:metabolism*; D000447:Aldehydes / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D004790:Enzyme Induction; D007659:Ketones / Q000378:metabolism; D015227:Lipid Peroxidation; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D009249:NADP / Q000378:metabolism*; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D051381:Rats; D013379:Substrate Specificity
chemical_list: D000447:Aldehydes; D000975:Antioxidants; D007659:Ketones; D009249:NADP; D000429:Alcohol Oxidoreductases; C082646:leukotriene B4 12-hydroxydehydrogenase; D011452:15-Oxoprostaglandin 13-Reductase; C027576:4-hydroxy-2-nonenal