title: Two-electron oxidation of deoxyguanosine by a Ru(III) complex without involving oxygen molecules through disproportionation.
abstract: Among the many mechanisms for the oxidation of guanine derivatives (G) assisted by transition metals, Ru(III) and Pt(IV) metal ions share basically the same principle. Both Ru(III)- and Pt(IV)-bound G have highly positively polarized C8-H's that are susceptible to deprotonation by OH(-), and both undergo two-electron redox reactions. The main difference is that, unlike Pt(IV), Ru(III) is thought to require O(2) to undergo such a reaction. In this study, however, we report that [Ru(III)(NH(3))(5)(dGuo)] (dGuo = deoxyguanosine) yields cyclic-5'-O-C8-dGuo (a two-electron G oxidized product, cyclic-dGuo) without O(2). In the presence of O(2), 8-oxo-dGuo and cyclic-dGuo were observed. Both [Ru(II)(NH(3))(5)(dGuo)] and cyclic-dGuo were produced from [Ru(III)(NH(3))(5)(dGuo)] accelerated by [OH(-)]. We propose that [Ru(III)(NH(3))(5)(dGuo)] disproportionates to [Ru(II)(NH(3))(5)(dGuo)] and [Ru(IV)(NH(3))(4)(NH(2)(-))(dGuo)], followed by a 5'-OH attack on C8 in [Ru(IV)(NH(3))(4)(NH(2)(-))(dGuo)] to initiate an intramolecular two-electron transfer from dGuo to Ru(IV), generating cyclic-dGuo and Ru(II) without involving O(2).
authors.affiliation: Department of Chemistry and Biochemistry, Middlebury College, Middlebury, Vermont 05753, USA. choi@middlebury.edu
authors.forename: Sunhee
authors.initials: S
authors.lastname: Choi
authors.forename: DaWeon
authors.initials: D
authors.lastname: Ryu
authors.forename: Joseph G
authors.initials: JG
authors.lastname: DellaRocca
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Wolf
authors.forename: Justin A
authors.initials: JA
authors.lastname: Bogart
mesh_terms: D003849:Deoxyguanosine / Q000737:chemistry*; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D009690:Nucleic Acid Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D012428:Ruthenium; D003849:Deoxyguanosine