电子附着于DNA：氨基酸的保护作用
Electron Attachment to DNA: The Protective Role of Amino Acids
AI总结：
本文以胞嘧啶为模型，利用运动方程耦合簇理论揭示组蛋白氨基酸通过门户态与物理屏蔽机制保护DNA核碱基、抑制糖—磷酸键断裂。
摘要：
我们以胞嘧啶作为模型体系，研究了氨基酸对DNA核碱基电子附着性质的影响。研究采用扩展基组的运动方程耦合簇理论，模拟该DNA模型体系的电子附着态。文中考察了四种选定的氨基酸——精氨酸、丙氨酸、赖氨酸和甘氨酸，它们是组蛋白的主要组成部分，用以探究其在电子附着到DNA核碱基过程中的作用。在所有胞嘧啶—氨基酸二聚体复合物中，电子对胞嘧啶的附着都遵循“门户”机制：电子通过电子自由度与核自由度的混合，从最初的偶极束缚门户态转移到最终的核碱基束缚态。在较高氨基酸浓度下，氨基酸束缚态充当门户态，初始电子密度定域在氨基酸上、远离核碱基。这使核碱基对入射的额外电子形成物理屏蔽。同时，氨基酸的存在能够提高核碱基束缚阴离子态的稳定性，从而抑制由解离性电子附着诱发的糖—磷酸键断裂。
英文摘要：
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.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
