title: Regulation of one-electron oxidation rate of guanine by base pairing with cytosine derivatives.
abstract: Effects of base pairing on the one-electron oxidation rate of guanine derivatives, guanine, 8-bromoguanine, and 8-oxo-7,8-dihydroguanine have been studied. The one-electron oxidation rate of guanine derivatives was determined by triplet-quenching experiments, using N,N'-dibutylnaphthaldiimide (NDI) in the triplet excited state (3NDI*) and fullerene (C(60)) in the triplet excited state ((3)C(60*)) as oxidants. In all three guanine derivatives studied here, acceleration of the one-electron oxidation was observed upon hydrogen bonding with cytosine, which demonstrates lowering of the oxidation potential of guanine derivatives by base pairing with cytosine. When a methyl or bromo group was introduced to the C5 position of cytosine, acceleration or suppression of the one-electron oxidation relative to the guanine:cytosine base pair was observed, respectively. The results demonstrate that the one-electron oxidation rate of guanine in DNA can be regulated by introducing a substituent on base pairing cytosine.
authors.affiliation: Contribution from The Institute of Scientific and Industrial Research (SANKEN), Osaka University, Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan. kiyohiko@sanken.osaka-u.ac.jp
authors.forename: Kiyohiko
authors.initials: K
authors.lastname: Kawai
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Wata
authors.forename: Michihiro
authors.initials: M
authors.lastname: Hara
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tojo
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D020029:Base Pairing; D003596:Cytosine / Q000031:analogs & derivatives* / Q000737:chemistry; D004247:DNA / Q000737:chemistry; D004563:Electrochemistry; D004583:Electrons; D006147:Guanine / Q000031:analogs & derivatives* / Q000737:chemistry; D007700:Kinetics; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010782:Photolysis
chemical_list: D006147:Guanine; D003596:Cytosine; D004247:DNA