Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, CAS, Shanghai 201203, P. R. China.
J Phys Chem B. 2012 Feb 2;116(4):1458-66. doi: 10.1021/jp211386x. Epub 2012 Jan 25.
Electron attachment to the trimer of nucleotide, dGpdCpdG, has been investigated by a quantum mechanical approach at a reliable level of theory. The study of the electron attached dGpdCpdG species demonstrates that cytosine contained DNA single strands have a strong tendency to capture low-energy electrons and to form electronically stable cytosine-centered radical anions. The comparative study of the model molecules pdCpdG and dGpdCp reveals that base stacking has little contribution to the adiabatic electron affinity (AEA) of cytosine in DNA single strands. Additionally, the base-base stacking does not affect the vertical detachment energy (VDE) of the cytosine-centered radicals. Intrastrand H-bonding is found to be critical in increasing the values of the AEA and VDE. However, base-base stacking is revealed to be important in enlarging the vertical electron affinity (VEA) of cytosine. The electron attachment to the cytosine moiety intensifies the intrastrand H-bonding between the neighboring G and C bases. This process disrupts the base-base stacking interaction in the radical anion of dGpdCpdG.
采用量子力学方法在可靠的理论水平上研究了核苷酸三聚体 dGpdCpdG 的电子附加。对电子附加的 dGpdCpdG 物种的研究表明，含有胞嘧啶的 DNA 单链具有强烈的捕获低能电子并形成电子稳定的胞嘧啶中心自由基阴离子的趋势。模型分子 pdCpdG 和 dGpdCp 的比较研究表明，碱基堆积对 DNA 单链中胞嘧啶的绝热电子亲和能（AEA）几乎没有贡献。此外，碱基-碱基堆积不影响胞嘧啶中心自由基的垂直离解能（VDE）。发现链内氢键对于增加 AEA 和 VDE 的值至关重要。然而，碱基-碱基堆积对于增大胞嘧啶的垂直电子亲和能（VEA）很重要。电子附加到胞嘧啶部分会加剧相邻 G 和 C 碱基之间的链内氢键。这个过程会破坏 dGpdCpdG 自由基阴离子中的碱基-碱基堆积相互作用。
