Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (12): 3329-3336.doi: 10.3866/PKU.WHXB20101136


Effect of Hydroxylation on Structures and Proton Transfer of A-T Base Pairs

SHI Jun-You1,2, DONG Li-Hua1,2, LIU Yong-Jun1   

  1. 1. Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining 810001, P. R. China;
    2. Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2010-08-02 Revised:2010-09-13 Published:2010-12-01
  • Contact: SHI Jun-You
  • Supported by:

    The project was supported by the Program of“One Hundred Talents Program”of the Chinese Academy of Sciences.


The structures and proton transfer processes of hydroxylated A-T base pairs were theoretically studied at the B3LYP/6-31++G(d,p)//B3LYP/6-31G(d,p) level. Our calculations revealed that hydroxyl radical could react with A-T at different positions to form eight stable adducts. The order of these adducts in energy is 8OHA-T6OH5OH<2OHA-T<4OHA-T<5OHA-T2OH4OH (the number denotes the label of the atom in the A/T which is attacked by hydroxyl), which relates well with their structural changes upon the addition of hydroxyl radical. The interaction energy between A and T would increase slightly when hydroxyl radical reacts with the adenine, but it would decrease when the radical reacts with thymine. To study the proton transfer processes of the hydroxylated A-T base pairs, the most stable adducts, 8OHA-T and A-T6OH, were selected to give calculations. The calculated results indicate that the proton transfer processes of 8OHA-T and A-T6OH follow the concerted mechanism, which is different from the stepwise mechanism of A-T. What is more, its energy barrier is lower than the corresponding energy of the latter's first step (rate-determining step).

Key words: Density functional theory, Base pair, Hydroxylation, Proton transfer, Singly occupied molecular orbital


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