Complete-active-space second-order perturbation theory (CASPT2//CASSCF) study of the dissociative electron attachment in canonical DNA nucleobases caused by low-energy electrons (0-3 eV)
Complete-active-space second-order perturbation theory (CASPT2//CASSCF) study of the dissociative electron attachment in canonical DNA nucleobases caused by low-energy electrons (0-3 eV)
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DOI：
10.1063/1.4936574
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发表时间：
2015-12-07
影响因子：
4.4
通讯作者：
Roca-Sanjuan, Daniel
中科院分区：
文献类型：
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作者：
Frances-Monerris, Antonio;Segarra-Marti, Javier;Roca-Sanjuan, Daniel
在生物材料辐照过程中产生的低能（0-3 eV）弹道电子可以与DNA/RNA核碱基相互作用，产生分解的瞬态阴离子物质。自从发现这些反应最终会导致DNA链断裂以来，人们一直在努力研究它们。在0-3 eV能量范围内，主要的分裂是一个氢原子从特定的氮位置喷出。在本研究中，采用了先前关于尿嘧啶的研究方法[1]。Gonzalez-Ramirez et al.， J. Chem。理论计算，8,2769-2776(2012)]研究了低能电子诱导的DNA典型核碱基N-H键断裂。该方法基于最小能量路径和沿N-H解离通道的内部坐标线性插值，在完全有效空间自洽场//完全有效空间二阶摄动理论水平上进行计算。在计算理论量的基础上，给出了腺嘌呤和胞嘧啶阴离子产率曲线的新定义。此外，嘧啶核碱基的π(-)(1)和π(-)(2)态预计会产生电子能分别接近1和2 eV的临时阴离子。最后，目前的理论结果不允许丢弃在所探索的能量范围内的偶极束缚机制和价键束缚机制，这表明这两种可能性在用孤立的核碱基进行的实验中可能共存。(C) 2015 AIP出版有限责任公司
Low-energy (0-3 eV) ballistic electrons originated during the irradiation of biological material can interact with DNA/RNA nucleobases yielding transient-anion species which undergo decompositions. Since the discovery that these reactions can eventually lead to strand breaking of the DNA chains, great efforts have been dedicated to their study. The main fragmentation at the 0-3 eV energy range is the ejection of a hydrogen atom from the specific nitrogen positions. In the present study, the methodological approach introduced in a previous work on uracil [I. Gonzalez-Ramirez et al., J. Chem. Theory Comput. 8, 2769-2776 (2012)] is employed to study the DNA canonical nucleobases fragmentations of N-H bonds induced by low-energy electrons. The approach is based on minimum energy path and linear interpolation of internal coordinates computations along the N-H dissociation channels carried out at the complete-active-space self-consistent field//complete-active-space second-order perturbation theory level. On the basis of the calculated theoretical quantities, new assignations for the adenine and cytosine anion yield curves are provided. In addition, the pi(-)(1) and pi(-)(2) states of the pyrimidine nucleobases are expected to produce the temporary anions at electron energies close to 1 and 2 eV, respectively. Finally, the present theoretical results do not allow to discard neither the dipole-bound nor the valence-bound mechanisms in the range of energies explored, suggesting that both possibilities may coexist in the experiments carried out with the isolated nucleobases. (C) 2015 AIP Publishing LLC.