title: Marked variations of dissociation energy and H-bond character of the guanine-cytosine base pair induced by one-electron oxidation and Li+ cation coupling.
abstract: The variation of dissociation energy and H-bond character of the G-C cation and the Li-GC cation have been investigated by employing density functional theory (B3LYP) with the 6-31+G* basis set. The one-electron oxidation and the coupling of Li(+) to the guanine-cytosine base pair can strengthen the interaction between guanine and cytosine. The interaction of the cation Li(+) with guanine is attractive and is attributed to the polarization of the H-bonds between G-C that enhances G-C interaction. The cooperativity of the three H-bonds in the GC and Li-GC cations is different from that in the neutral GC base pair. The proton-transfer process between N(1) of the guanine and N(3) of the cytosine can occur in the GC cation and the Li-GC cation. The geometries of the transition state are out of plane, especially for the transition state of the Li-GC cation. The analysis of the activation energy for the proton-transfer process shows that the GC(+) before and after proton transfer can exist simultaneously in the gas phase, but for the Li-GC(+) system, the Li-GC(+) without proton transfer is the dominating species in the gas phase.
authors.affiliation: Institute of Theoretical Chemistry, Shandong University, Jinan, 250100, P. R. China.
authors.forename: Lixiang
authors.initials: L
authors.lastname: Sun
authors.forename: Yuxiang
authors.initials: Y
authors.lastname: Bu
mesh_terms: D020029:Base Pairing; D002412:Cations / Q000737:chemistry; D003596:Cytosine / Q000737:chemistry*; D004583:Electrons; D004735:Energy Transfer; D006147:Guanine / Q000737:chemistry*; D006860:Hydrogen Bonding; D008094:Lithium / Q000737:chemistry*; D008956:Models, Chemical; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared / Q000379:methods
chemical_list: D002412:Cations; D006147:Guanine; D003596:Cytosine; D008094:Lithium