title: Comparison of Transition Metal-Mediated Oxidation Reactions of Guanine in Nucleoside and Single-Stranded Oligodeoxynucleotide Contexts.
abstract: As the most readily oxidized of DNA's four natural bases, guanine is a prime target for attack by reactive oxygen species (ROS) and transition metal-mediated oxidants. The oxidation products of a modified guanosine nucleoside and of a single-stranded oligodeoxynucleotide, 5'-d(TTTTTTTGTTTTTTT)-3' have been studied using oxidants that include Co(II), Ni(II), and Ir(IV) compounds as well as photochemically generated oxidants such as sulphate radical, electron-transfer agents (riboflavin) and singlet oxygen. The oxidized lesions formed include spiroiminodihydantoin (Sp), guanidinohydantoin (Gh), imidazolone (Iz), oxazolone (Z) and 5-carboxamido-5-formamido-2-iminohydantion (2-Ih) nucleosides with a high degree of dependence on the exact oxidation system employed. Interestingly, a nickel(II) macrocyclic complex in conjunction with KHSO(5) leads to the recently reported 2-Ih heterocycle as the major product in both the nucleoside and oligonucleotide contexts.
authors.affiliation: Department of Chemistry, University of Utah, 315 S 1400 East, Salt Lake City, UT 84112-0850, USA.
authors.forename: Pranjali
authors.initials: P
authors.lastname: Ghude
authors.forename: Mark A
authors.initials: MA
authors.lastname: Schallenberger
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Fleming
authors.forename: James G
authors.initials: JG
authors.lastname: Muller
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Burrows