Proton-coupled electron transfer in DNA-acrylamide complexes
Proton-coupled electron transfer in DNA-acrylamide complexes
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DOI：
10.1021/jp0209392
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发表时间：
2002-08-22
影响因子：
3.3
通讯作者：
Hammes-Schiffer, S
中科院分区：
文献类型：
--
作者：
Carra, C;Iordanova, N;Hammes-Schiffer, S
提出了自由基阴离子胸腺嘧啶-丙烯酰胺复合物中质子耦合电子转移（PCET）的理论研究。本研究基于多态连续体理论，其中溶质由多态价键模型表示，溶剂由介电连续体描述，转移的氢核由量子力学波函数表示。在该应用中，基态和激发电子态用完全活性空间自洽场（CASSCF）方法计算，电子转移反应的电子耦合用广义Mulliken-Hush方法计算，溶剂化性质用频率分辨腔模型计算。除了溶剂化胸腺嘧啶-丙烯酰胺复合物之外，还通过研究溶剂化 DNA-丙烯酰胺模型来确定相邻 DNA 碱基对的影响。计算表明，最终产物对应于溶剂化胸腺嘧啶-丙烯酰胺复合物的单电子转移(ET)，但对应于溶剂化DNA-丙烯酰胺复合物的净PCET反应。这种差异是由于 DNA 存在时溶剂可及性降低，从而改变了 ET 和 PCET 产物状态的相对自由能。因此，DNA-丙烯酰胺系统中ET和PCET之间的平衡对系统的溶剂化特性高度敏感。
A theoretical study of proton-coupled electron transfer (PCET) in the radical anionic thymine-acrylamide complex is presented. This study is based on a multistate continuum theory, in which the solute is represented by a multistate valence bond model, the solvent is described by a dielectric continuum, and the transferring hydrogen nucleus is represented by a quantum mechanical wave function. In this application, the ground and excited electronic states are calculated with the complete active space self-consistent-field (CASSCF) method, the electronic coupling for the electron transfer reaction is calculated with the generalized Mulliken-Hush method, and the solvation properties are calculated with the frequency-resolved cavity model. The influence of neighboring DNA base pairs is determined by studying solvated DNA-acrylamide models in addition to the solvated thymine-acrylamide complex. The calculations indicate that the final product corresponds to single electron transfer (ET) for the solvated thymine-acrylamide complex but to a net PCET reaction for the solvated DNA-acrylamide complex. This difference is due to a decrease in solvent accessibility in the presence of DNA, which alters the relative free energies of the ET and PCET product states. Thus, the balance between ET and PCET in the DNA-acrylamide system is highly sensitive to the solvation properties of the system.