title: Proton Transfer of Guanine Radical Cations Studied by Time-Resolved Resonance Raman Spectroscopy Combined with Pulse Radiolysis.
abstract: The oxidation of guanine (G) is studied by using transient absorption and time-resolved resonance Raman spectroscopies combined with pulse radiolysis. The transient absorption spectral change demonstrates that the neutral radical of G (G(•)(-H(+))), generated by the deprotonation of G radical cation (G(•+)), is rapidly converted to other G radical species. The formation of this species shows the pH dependence, suggesting that it is the G radical cation (G(•+))' formed from the protonation at the N7 of G(•)(-H(+)). On one hand, most Raman bands of (G(•+))' are up-shifted relative to those of G, indicating the increase in the bonding order of pyrimidine (Pyr) and imidazole rings. The (G(•+))' exhibits the characteristic CO stretching mode at ∼1266 cm(-1) corresponding to a C-O single bond, indicating that the unpaired electron in (G(•+))' is localized on the oxygen of the Pyr ring.
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.|Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon 305-701, Republic of Korea.
authors.forename: Jungkweon
authors.initials: J
authors.lastname: Choi
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon 305-701, Republic of Korea.|Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Cheolhee
authors.initials: C
authors.lastname: Yang
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Mamoru
authors.initials: M
authors.lastname: Fujitsuka
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Sachiko
authors.initials: S
authors.lastname: Tojo
authors.affiliation: Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon 305-701, Republic of Korea.|Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
authors.forename: Hyocherl
authors.initials: H
authors.lastname: Ihee
authors.affiliation: The Institute of Scientific and Industrial Research (SANKEN), Osaka University , Mihogaoka 8-1, Ibaraki, Osaka 567-0047, Japan.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Majima
mesh_terms: D002412:Cations; D006147:Guanine / Q000737:chemistry*; D011675:Pulse Radiolysis; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D002412:Cations; D006147:Guanine
keywords: guanine; one-electron oxidation; proton transfer; pulse radiolysis; time-resolved resonance Raman