title: Hydrogen-bonded double-proton transfer in five guanine-cytosine base pairs after hydrogen atom addition.
abstract: The double-proton transfer reactions in Watson-Crick guanine-cytosine (GC) base pairs after hydrogen atom addition are studied theoretically. The structural changes and energy differences among the structures are compared to explore the double-proton transfer mechanisms, concerted and stepwise. The concerted mechanism is found in all five radicals (GC+H)(•) considered, while the stepwise mechanism is predicted only for structures G-H(•)C(C6) and H(•)G(N7)-C. The geometrical features have been found to change regularly in the concerted double-proton transfer. This is different from the single-proton transfer, for which the structural perturbations are dispersed throughout the GC base pair. The energy analyses demonstrate that the concerted double-proton transfer mechanism is more favorable in the gas phase, while the stepwise mechanism dominates in water. The structures of proton transfer products become less favored energetically.
authors: School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, P. R. China.
authors: Yuexia
authors: Y
authors: Lin
authors: Hongyan
authors: H
authors: Wang
authors: Simin
authors: S
authors: Gao
authors: Ruhu
authors: R
authors: Li
authors: Henry F
authors: HF
authors: Schaefer
mesh_terms: D020029:Base Pairing; D003596:Cytosine / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D006147:Guanine / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D011522:Protons; D014867:Water / Q000737:chemistry
chemical_list: D005740:Gases; D011522:Protons; D014867:Water; D006147:Guanine; D006859:Hydrogen; D003596:Cytosine