title: Generation of guanine-thymine cross-links in human cells by one-electron oxidation mechanisms.
abstract: The one-electron oxidation of cellular DNA in cultured human HeLa cells initiated by intense nanosecond 266 nm laser pulse irradiation produces cross-links between guanine and thymine bases (G*-T*), characterized by a covalent bond between C8 guanine (G*) and N3 thymine (T*) atoms. The DNA lesions were quantified by isotope dilution LC-MS/MS methods in the multiple reaction-monitoring mode using isotopically labeled [(15)N, (13)C]-nucleotides as internal standards. Among several known pyrimidine and 8-oxo-7,8-dihydroguanine lesions, the G*-T* cross-linked lesions were detected at levels of ~0.21 and 1.19 d(G*-T*) lesions per 10(6) DNA bases at laser intensities of 50 and 280 mJ/cm(2)/pulse, respectively.
authors.affiliation: Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine, 3001 12e Avenue Nord, Université de Sherbrooke , Québec J1H 5N4, Canada.
authors.forename: Guru S
authors.initials: GS
authors.lastname: Madugundu
authors.forename: J Richard
authors.initials: JR
authors.lastname: Wagner
authors.forename: Jean
authors.initials: J
authors.lastname: Cadet
authors.forename: Konstantin
authors.initials: K
authors.lastname: Kropachev
authors.forename: Byeong Hwa
authors.initials: BH
authors.lastname: Yun
authors.forename: Nicholas E
authors.initials: NE
authors.lastname: Geacintov
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shafirovich
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004249:DNA Damage; D004583:Electrons; D005609:Free Radicals / Q000737:chemistry; D006147:Guanine / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007834:Lasers; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013941:Thymine / Q000737:chemistry*
chemical_list: D003432:Cross-Linking Reagents; D005609:Free Radicals; D006147:Guanine; D004247:DNA; D013941:Thymine