title: Dichlorobenzidine-DNA binding catalyzed by peroxidative activation in Salmonella typhimurium.
abstract: Peroxidative oxidation of dichlorobenzidine in vitro results in covalent binding to exogenous DNA. In a modified Ames assay, mutagenicity is observed in S. typhimurium strain TA98 following the incubation of dichlorobenzidine, bacteria, and hydrogen peroxide. In this paper, we demonstrate that [14C]dichlorobenzidine becomes covalently bound to S. typhimurium macromolecules, including DNA, when exogenous hydrogen peroxide is supplied. We compared the levels of binding in a pair of otherwise isogenic strains with wild-type (oxyR+) versus constitutive (oxyR1) expression of the hydrogen peroxide stress-induced regulon. Binding was approximately twofold higher in TA4124 (oxyR1) than in TA4123 (oxyR+). Bacterial hydroperoxidases may catalyze the activation of dichlorobenzidine to mutagenic and DNA binding species in this system.
authors.affiliation: Guelph-Waterloo Centre for Graduate Work in Chemistry, University of Guelph, Ontario, Canada.
authors.forename: L S
authors.initials: LS
authors.lastname: DeBruin
authors.forename: P D
authors.initials: PD
authors.lastname: Josephy
mesh_terms: D015101:3,3'-Dichlorobenzidine / Q000633:toxicity*; D001560:Benzidines / Q000633:toxicity*; D002374:Catalase / Q000302:isolation & purification / Q000378:metabolism; D002384:Catalysis; D004247:DNA / Q000187:drug effects* / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000633:toxicity*; D046911:Macromolecular Substances; D009152:Mutagenicity Tests; D012486:Salmonella typhimurium / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D013045:Species Specificity / Q000187:drug effects
chemical_list: D001560:Benzidines; D046911:Macromolecular Substances; D015101:3,3'-Dichlorobenzidine; C029876:benzidine; D004247:DNA; D006861:Hydrogen Peroxide; D002374:Catalase