title: DNA damage by the sulfate radical anion: hydrogen abstraction from the sugar moiety versus one-electron oxidation of guanine.
abstract: The products of oxidative damage to double-stranded (ds) DNA initiated by photolytically generated sulfate radical anions SO4(•-) were analyzed using reverse-phase (RP) high-performance liquid chromatography (HPLC). Relative efficiencies of two major pathways were compared: production of 8-oxoguanine (8oxoG) and hydrogen abstraction from the DNA 2-deoxyribose moiety (dR) at C1,' C4,' and C5' positions. The formation of 8oxoG was found to account for 87% of all quantified lesions at low illumination doses. The concentration of 8oxoG quickly reaches a steady state at about one 8oxoG per 100 base pairs due to further oxidation of its products. It was found that another guanine oxidation product identified as 2-amino-5-(2'-alkylamino)-4H-imidazol-4-one (X) was released in significant quantities from its tentative precursor 2-amino-5-[(2'-deoxy-β-d-erythro-pentofuranosyl)amino]-4H-imidazol-4-one (dIz) upon treatment with primary amines in neutral solutions. The linear dose dependence of X release points to the formation of dIz directly from guanine and not through oxidation of 8oxoG. The damage to dR was found to account for about 13% of the total damage, with majority of lesions (33%) originating from the C4' oxidation. The contribution of C1' oxidation also turned out to be significant (17% of all dR damages) despite of the steric problems associated with the abstraction of the C1'-hydrogen. However, no evidence of base-to-sugar free valence transfer as a possible alternative to direct hydrogen abstraction at C1' was found.
authors.affiliation: a Department of Chemistry , East Tennessee State University , Johnson City , TN , USA ;
authors.forename: Marina
authors.initials: M
authors.lastname: Roginskaya
authors.affiliation: a Department of Chemistry , East Tennessee State University , Johnson City , TN , USA ;
authors.forename: Reza
authors.initials: R
authors.lastname: Mohseni
authors.affiliation: b Department of Chemistry , Virginia Commonwealth University , Richmond , VA , USA ;
authors.forename: Derrick
authors.initials: D
authors.lastname: Ampadu-Boateng
authors.affiliation: c Department of Physics and Astronomy , East Tennessee State University , Johnson City , TN , USA.
authors.forename: Yuriy
authors.initials: Y
authors.lastname: Razskazovskiy
mesh_terms: D000838:Anions / Q000737:chemistry*; D004249:DNA Damage; D006147:Guanine / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry; D007093:Imidazoles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013431:Sulfates / Q000737:chemistry*
chemical_list: D000838:Anions; D007093:Imidazoles; D013431:Sulfates; C069025:sulfate radical; D006147:Guanine; C029899:imidazole; D006859:Hydrogen
keywords: 8-oxoguanine; DNA; imidazolone; oxidative damage; sulfate radicals