title: Metabolism of trans, trans-muconaldehyde, a cytotoxic metabolite of benzene, in mouse liver by alcohol dehydrogenase Adh1 and aldehyde reductase AKR1A4.
abstract: The reductive metabolism of trans, trans-muconaldehyde, a cytotoxic metabolite of benzene, was studied in mouse liver. Using an HPLC-based stopped assay, the primary reduced metabolite was identified as 6-hydroxy-trans, trans-2,4-hexadienal (OH/CHO) and the secondary metabolite as 1,6-dihydroxy-trans, trans-2,4-hexadiene (OH/OH). The main enzymes responsible for the highest levels of reductase activity towards trans, trans-muconaldehyde were purified from mouse liver soluble fraction first by Q-sepharose chromatography followed by either blue or red dye affinity chromatography. In mouse liver, trans, trans-muconaldehyde is predominantly reduced by an NADH-dependent enzyme, which was identified as alcohol dehydrogenase (Adh1). Kinetic constants obtained for trans, trans-muconaldehyde with the native Adh1 enzyme showed a Vmax of 2141+/-500 nmol/min/mg and a Km of 11+/-4 microM. This enzyme was inhibited by pyrazole with a KI of 3.1+/-0.57 microM. Other fractions were found to contain muconaldehyde reductase activity independent of Adh1, and one enzyme was identified as the NADPH-dependent aldehyde reductase AKR1A4. This showed a Vmax of 115 nmol/min/mg and a Km of 15+/-2 microM and was not inhibited by pyrazole.
authors.affiliation: Department of Bioscience, University of Strathclyde, 204 George Street, Glasgow, G1 1XW Scotland, UK.
authors.forename: Duncan M
authors.initials: DM
authors.lastname: Short
authors.forename: Robert
authors.initials: R
authors.lastname: Lyon
authors.forename: David G
authors.initials: DG
authors.lastname: Watson
authors.forename: Oleg A
authors.initials: OA
authors.lastname: Barski
authors.forename: Gail
authors.initials: G
authors.lastname: McGarvie
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Ellis
mesh_terms: D000426:Alcohol Dehydrogenase / Q000378:metabolism*; D000449:Aldehyde Reductase / Q000378:metabolism*; D000447:Aldehydes / Q000493:pharmacokinetics*; D000818:Animals; D001554:Benzene / Q000378:metabolism*; D003001:Cloning, Molecular; D066298:In Vitro Techniques; D008658:Inactivation, Metabolic; D008099:Liver / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013237:Stereoisomerism
chemical_list: D000447:Aldehydes; C034476:muconaldehyde; D000426:Alcohol Dehydrogenase; C000627720:Akr1a1 protein, mouse; D000449:Aldehyde Reductase; D001554:Benzene