The role of πσ* excited states in electron-induced DNA strand break formation:: A time-dependent density functional theory study
The role of πσ* excited states in electron-induced DNA strand break formation:: A time-dependent density functional theory study
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DOI：
10.1021/ja077331x
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发表时间：
2008-02-20
影响因子：
15
通讯作者：
Sevilla, Michael D.
中科院分区：
文献类型：
--
作者：
Kumar, Anil;Sevilla, Michael D.
低能电子附着在DNA上并随后形成单链断裂（SSB）的机制对于理解DNA损伤至关重要。本研究采用含时密度泛函理论（TD-BH&HLYP/6- 31 G *），以DNA为模型，通过计算5 '-dTMPH自由基阴离子的最低激发态，详细探讨了SSB的机理。5 ′-dTMPH自由基阴离子的C-5-O-5键解离被认为是沿着5 ′-dTMPH势能面上的反应配位。主要位于5 '-dTMPH自由基阴离子的磷酸根上的解离σ * 态被认为是DNA中SSB形成的原因。我们的工作预测，在这个DNA模型系统中，有可用的π * 和西格玛 * 激发态，近2 eV，它可以耦合振动，并导致DNA单链断裂通过解离西格玛 * 表面。
Mechanisms of low-energy electron attachment to the DNA and subsequent single-strand break (SSB) formation are of crucial importance to understand the DNA damage. In the present study, we used time-dependent density functional theory (TD-BH&HLYP/6-31G*) to explore the mechanism of SSB, in detail, by calculating the lowest excited states of 5'-dTMPH radical anion considered as a model of DNA. The C-5-O-5, bond dissociation of 5'-dTMPH radical anion was considered as the reaction coordinate along the potential energy surface of 5'-dTMPH. The dissociative sigma* state, mainly localized on the phosphate of the 5'-dTMPH radical anion, is considered responsible for the SSB formation in DNA. Our work predicts that in this DNA model system there are available pi* and sigma* excited states, near 2 eV, which can couple vibronically and lead to a DNA single strand break via the dissociative sigma* surface.