Structure elucidation of a 6-methylbenzo[a]pyrene-DNA adduct formed by horseradish peroxidase in vitro and mouse skin in vivo.
Activation of polycyclic aromatic hydrocarbons (PAH) by horseradish peroxidase (HRP) with H2O2 has been studied as a model system for one-electron oxidation. This peroxidase has been used to catalyze binding of 6-[14C]methylbenzo[a]pyrene (BP-6-CH3) to DNA, which was purified, hydrolyzed to deoxyribonucleosides and analyzed by high pressure liquid chromatography (HPLC). The predominant hydrocarbon-DNA adduct observed was identified as BP-6-CH3 bound at the 6-methyl group to the 2-amino group of dG, confirming that activation by HRP occurs by one-electron oxidation. When DNA from mouse skin treated in vivo with [14C]BP-6-CH3 was purified, hydrolyzed and analyzed by HPLC, a profile was observed which was qualitatively similar to that from the peroxidase system. In particular, the identified adduct with the hydrocarbon bound at the 6-methyl group to the 2-amino group of dG was obtained. These results demonstrate that one-electron oxidation is the mechanism of activation by HRP for aromatic hydrocarbons and indicate that the same mechanism may occur in mouse skin, a target tissue for hydrocarbon carcinogenesis.
D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism*; D005260:Female; D006735:Horseradish Peroxidase / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D051379:Mice; D010084:Oxidation-Reduction; D010544:Peroxidases / Q000378:metabolism*; D012867:Skin / Q000378:metabolism
D001580:Benzopyrenes; C017503:6-methylbenzo(a)pyrene; D004247:DNA; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase; D010544:Peroxidases