Aldehyde Dehydrogenase 1B1: Molecular Cloning and Characterization of a Novel Mitochondrial Acetaldehyde-Metabolizing Enzyme

Abstract

ABSTRACT:Ethanol-induced damage is largely attributed to its toxic metabolite, acetaldehyde. Clearance of acetaldehyde is achieved by its oxidation, primarily catalyzed by the mitochondrial class II aldehyde dehydrogenase (ALDH2). ALDH1B1 is another mitochondrial aldehyde dehydrogenase (ALDH) that shares 75% peptide sequence homology with ALDH2. Recent population studies in whites suggest a role for ALDH1B1 in ethanol metabolism. However, to date, no formal documentation of the biochemical properties of ALDH1B1 has been forthcoming. In this current study, we cloned and expressed human recombinant ALDH1B1 in Sf9 insect cells. The resultant enzyme was purified by affinity chromatography to homogeneity. The kinetic properties of purified human ALDH1B1 were assessed using a wide range of aldehyde substrates. Human ALDH1B1 had an exclusive preference for NAD ؉ as the cofactor and was catalytically active toward short-and medium-chain aliphatic aldehydes, aromatic aldehydes, and the products of lipid peroxidation, 4-hydroxynonenal and malondialdehyde. Most importantly, human ALDH1B1 exhibited an apparent K m of 55 M for acetaldehyde, making it the second low K m ALDH for metabolism of this substrate. The dehydrogenase activity of ALDH1B1 was sensitive to disulfiram inhibition, a feature also shared with ALDH2. The tissue distribution of ALDH1B1 in C57BL/6J mice and humans was examined by quantitative polymerase chain reaction, Western blotting, and immunohistochemical analysis. The highest expression occurred in the liver, followed by the intestinal tract, implying a potential physiological role for ALDH1B1 in these tissues. The current study is the first report on the expression, purification, and biochemical characterization of human ALDH1B1 protein.

Aldehyde Dehydrogenase Inhibitors: a Comprehensive Review of the Pharmacology, Mechanism of Action, Substrate Specificity, and Clinical Application

“…Other ALDHs, including ALDH1A1 and ALDH1B1, also contribute to acetaldehyde oxidation, albeit with lesser affinity than the ALDH2 isozyme Stagos et al, 2010). A genetic polymorphism in the ALDH2 gene can result in a substantial decrease in its acetaldehyde metabolizing capacity.…”

Metabolism of MRX-I, a Novel Antibacterial Oxazolidinone, in Humans: The Oxidative Ring Opening of 2,3-Dihydropyridin-4-One Catalyzed by Non-P450 Enzymes

“…To determine the enzymes responsible for the formation of metabolites related to the MRX-I DHPO ring opening, various specific phenotypic inhibitors were added to the S9 fraction incubation system: ABT [1000 mM final concentration, cytochrome P450 (P450) inhibitor], methimazole (100 mM final concentration, P450 and FMO inhibitor, except FMO5), menadione [1-100 mM final concentration, aldehyde oxidase (AO) and short-chain dehydrogenase reductase (SDR) inhibitor] (Rosemond and Walsh, 2004;Morrison et al, 2012), raloxifene (0.001-100 mM final concentration, AO inhibitor), methotrexate [50 mM final concentration, xanthine oxidase (XO) inhibitor], allopurinol (100 mM final concentration, XO inhibitor) (Morrison et al, 2012) (Stagos et al, 2010). After these inhibitors were incubated with human liver S9 fractions in the presence of NADPH for 15 minutes, the MRX-I in methanol stock solution was added to the incubation system.…”

Cytochrome P450 and Non-Cytochrome P450 Oxidative Metabolism: Contributions to the Pharmacokinetics, Safety, and Efficacy of Xenobiotics

“…Perhaps the most well known function of the ADHs is their role in the metabolism of ethanol, with alterations in the functions of the enzymes being linked to various physiologic ramifications of alcoholism. From an endogenous standpoint, two key roles for ALDHs are the conversion of retinaldehyde to retinoic acid, a metabolic conversion that is involved in the regulation of a host of homeostatic functions, as well as the metabolism of acetaldehyde, a by-product of ethanol metabolism (Stagos et al, 2010;Singh et al, 2013). One of the key xenobiotic roles for ALDH is the bioactivation of nitroglycerin to nitric oxide, resulting in the drug's vasodilatory effects (Chen et al, 2002;Wenzl et al, 2011).…”