title: Enantioselective oxidation of trans-4-hydroxy-2-nonenal is aldehyde dehydrogenase isozyme and Mg2+ dependent.
abstract: trans-4-Hydroxy-2-nonenal (HNE) is a cytotoxic alpha,beta-unsaturated aldehyde implicated in the pathology of multiple diseases involving oxidative damage. Oxidation of HNE by aldehyde dehydrogenases (ALDHs) to trans-4-hydroxy-2-nonenoic acid (HNEA) is a major route of metabolism in many organisms. HNE exists as two enantiomers, (R)-HNE and (S)-HNE, and in intact rat brain mitochondria, (R)-HNE is enantioselectively oxidized to HNEA. In this work, we further elucidated the basis of the enantioselective oxidation of HNE by brain mitochondria. Our results showed that (R)-HNE is oxidized enantioselectively by brain mitochondrial lysates with retention of stereoconfiguration of the C4 hydroxyl group. Purified rat ALDH5A enantioselectively oxidized (R)-HNE, whereas rat ALDH2 was not enantioselective. Kinetic data using (R)-HNE, (S)-HNE, and trans-2-nonenal in combination with computer-based modeling of ALDH5A suggest that the selectivity of (R)-HNE oxidation by ALDH5A is the result of the carbonyl carbon of (R)-HNE forming a more favorable Bürgi-Duntiz angle with the active site cysteine 293. The presence of Mg2+ ions altered the enantioselectivity of ALDH5A and ALDH2. Mg2+ ions suppressed (R)-HNE oxidation by ALDH5A to a greater extent than that of (S)-HNE. However, Mg2+ ions stimulated the enantioselective oxidation of (R)-HNE by ALDH2 while suppressing (S)-HNE oxidation. These results demonstrate that enantioselective utilization of substrates, including HNE, by ALDHs is dependent upon the ALDH isozyme and the presence of Mg 2+ ions.
authors.affiliation: Department of Pharmacology, Physiology, and Therapeutics, University of North Dakota, Grand Forks, North Dakota 58202-9024, USA.
authors.forename: Jiri
authors.initials: J
authors.lastname: Brichac
authors.forename: Kwok Ki
authors.initials: KK
authors.lastname: Ho
authors.forename: Ales
authors.initials: A
authors.lastname: Honzatko
authors.forename: Rongying
authors.initials: R
authors.lastname: Wang
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Lu
authors.forename: Henry
authors.initials: H
authors.lastname: Weiner
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Picklo
mesh_terms: D000079:Acetaldehyde / Q000737:chemistry / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000737:chemistry / Q000378:metabolism*; D000447:Aldehydes / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D002384:Catalysis / Q000187:drug effects; D002413:Cations, Divalent / Q000737:chemistry / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry / Q000494:pharmacology*; D008958:Models, Molecular; D009243:NAD / Q000737:chemistry / Q000378:metabolism; D010084:Oxidation-Reduction; D011487:Protein Conformation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D005680:gamma-Aminobutyric Acid / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism
chemical_list: D000447:Aldehydes; D002413:Cations, Divalent; D007527:Isoenzymes; D009243:NAD; D005680:gamma-Aminobutyric Acid; D000444:Aldehyde Dehydrogenase; D000079:Acetaldehyde; D008274:Magnesium; C027576:4-hydroxy-2-nonenal; C009338:succinic semialdehyde