title: 5,6-Dihydropyrimidine peroxyl radical reactivity in DNA.
abstract: Nucleobase radicals are a major family of reactive species produced in DNA as a result of oxidative stress. Two such radicals, 5-hydroxy-5,6-dihydrothymidin-6-yl radical (1) and 5,6-dihydrouridin-6-yl radical (5), were independently generated within chemically synthesized oligonucleotides from photochemical precursors. Neither nucleobase radical produces direct strand breaks or alkali-labile lesions in single or double stranded DNA. The respective peroxyl radicals, resulting from O2 trapping, add to 5'-adjacent nucleobases, with a preference for dG. Distal dG's are also oxidatively damaged by the peroxyl radicals. Experiments using a variety of sequences indicate that distal damage occurs via covalent modification of the 5'-adjacent dG, but there is no evidence for electron transfer by the nucleobase peroxyl radicals.
authors.affiliation: Department of Chemistry, Johns Hopkins University , 3400 N. Charles St., Baltimore, Maryland 21218, United States.
authors.forename: Joanna Maria N
authors.initials: JM
authors.lastname: San Pedro
authors.forename: Marc M
authors.initials: MM
authors.lastname: Greenberg
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D004249:DNA Damage; D005609:Free Radicals / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D011743:Pyrimidines / Q000737:chemistry*
chemical_list: C586280:1,4-dihydropyrimidine; D005609:Free Radicals; D010545:Peroxides; D011743:Pyrimidines; C049375:perhydroxyl radical; D004247:DNA