论文标题
电子附着DNA：氨基酸的保护作用
Electron Attachment to DNA: The Protective Role of Amino Acids
论文作者
论文摘要
我们已经研究了氨基酸对DNA核碱基电子附着特性的影响，以胞嘧啶为模型系统。具有扩展基集的运动耦合群集理论方程已用于模拟DNA模型系统的电子附件状态。考虑了组成组蛋白的主要成分的四种选定的氨基酸，精氨酸，丙氨酸，赖氨酸和甘氨酸，以研究其在电子与DNA核苷酸酶的附着中的作用。在所有胞质 - 氨基酸二聚体复合物中的电子附着在胞质上，遵循门口机制，在该机构中，电子通过电子和核自由度的混合，将电子从初始偶极子结合的门口态转移到最终的核碱基结合状态。在较高的氨基酸浓度中，结合氨基酸的状态充当门口状态，其中初始电子密度位于氨基酸，远离核碱基。这导致核酶从传入的额外电子中产生物理屏蔽。同时，氨基酸的存在可以提高核碱基结合的阴离子状态的稳定性，从而抑制解离电子附着会诱导糖磷酸键断裂。
We have studied the effect of amino acids on electron attachment properties of DNA nucleobases, taking cytosine as a model system. The equation of motion coupled cluster theory with an extended basis set has been used to simulate the electron-attached state of the DNA model system. Four selected amino acids, Arginine, Alanine, Lysine, and Glycine which form a major component of histone proteins are considered to investigate their role in electron attachment to DNA nucleobase. The electron attachment to cytosine in all the cytosine-amino acid dimer complexes follows a doorway mechanism, where the electron gets transferred from initial dipole-bound doorway state to the final nucleobase-bound state through the mixing of electronic and nuclear degrees of freedom. In higher amino acid concentration, amino acid-bound state acts as the doorway state, where the initial electron density is localized on the amino acid, away from the nucleobase. This leads to the physical shielding of nucleobase from the incoming extra electron. At the same time, the presence of amino acids can increase the stability of nucleobase-bound anionic state, which can suppress the dissociative electron attachment induced sugar-phosphate bond breaking.
