title: A new understanding towards the reactivity of DNA peroxy radicals.
abstract: The reactivity of thymine peroxy radicals in DNA and their fate are studied using the reliable DFT methods. The most accessible H1' abstraction by the C6-peroxyl once reported experimentally is effectively competitive to the crosslinking reaction between the C6-peroxyl and the C5 or C6 on the 5'-adjacent thymine base. The rare transfer of the ObH1' group to the C1' radical from the formed hydroperoxide happens with a very strong heat release. Afterwards, the parallel reactions including the H1' and H2' abstractions by the C6-alkoxyl in an inter-nucleotidyl manner lead to direct formation of thymine glycol. After the H1' abstraction by the C6-alkoxyl, the apyrimidinic site can be formed on C1' through effective N1-glycosidic bond rupture. The geometric rearrangements and the orbital interaction between the H donor and the σ-type H acceptor are used to explain the difference of the H2' abstraction barriers by C6-alkoxyl. Hence, new radical reaction paths for the formation of DNA oxidation products are suggested, which are strongly different from the previously suggested paths with the tetraoxide intermediate.
authors: School of Chemistry, Beijing Institute of Technology, South Street No. 5, Zhongguancun, Haidian District, 100081 Beijing, China. zhangrubo@bit.edu.cn.
authors: Shuang
authors: S
authors: Zhao
authors: Ru-Bo
authors: RB
authors: Zhang
authors: Ze-Sheng
authors: ZS
authors: Li
mesh_terms: D004247:DNA / Q000737:chemistry*; D005609:Free Radicals / Q000737:chemistry*; D005740:Gases / Q000737:chemistry; D010084:Oxidation-Reduction; D013816:Thermodynamics; D013941:Thymine / Q000031:analogs & derivatives / Q000737:chemistry; D014867:Water / Q000737:chemistry
chemical_list: D005609:Free Radicals; D005740:Gases; D014867:Water; C029389:thymine glycol; D004247:DNA; D013941:Thymine