Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, San Rafael Atlixco 186, Col. Vicentina, Iztapalapa, C. P. 09340, México DF, México.
Phys Chem Chem Phys. 2012 Sep 28;14(36):12476-84. doi: 10.1039/c2cp40799j. Epub 2012 May 29.
Different deprotonation paths of the radical cation formed by one-electron oxidation of 2'-deoxyguanosine (2dG) sites in DNA have been studied using Density Functional Theory (M05-2X/6-31+G(d,p)) and ONIOM methodology (M05-2X/6-31+G(d,p):PM6) in conjunction with the SMD model to include the solvent effects. Models of increased complexity have been used ranging from the isolated nucleoside to a three unit double-stranded oligomer including the sugar units, the base pairing with cytidine, and the phosphate linkage. The reported results correspond to aqueous solution, at room temperature, and pH = 7.4. Under such conditions it was found that the proton transfer (PT) within the base pair is a minor path compared to the PT between the base pair and the surrounding water. It was also found that the deprotonation of ground-state 2dG˙(+) sites mainly yields C centered radicals in the sugar unit, with the largest populations corresponding to C4'˙ and C5'˙, followed by C3'˙. The different aspects of the presented theoretical study have been validated with experimental results.
使用密度泛函理论（M05-2X/6-31+G(d,p)）和 ONIOM 方法（M05-2X/6-31+G(d,p):PM6）结合 SMD 模型来包含溶剂效应，研究了 DNA 中 2'-脱氧鸟苷（2dG）位点单电子氧化形成的自由基阳离子的不同去质子化途径。使用了从孤立核苷到包括糖单元、与胞嘧啶碱基配对和磷酸键的三个单元双链寡聚物的增加复杂性的模型。报告的结果对应于水溶液，在室温下，pH = 7.4。在这种条件下，发现碱基对内部的质子转移（PT）与碱基对与周围水之间的 PT 相比是次要途径。还发现，处于基态的 2dG˙(+)位点的去质子化主要在糖单元中生成 C 中心自由基，其中最大的部分对应于 C4'˙和 C5'˙，其次是 C3'˙。所提出的理论研究的不同方面已经通过实验结果得到了验证。
