环丁烷嘧啶二聚体损伤修复过程中初始电子转移的核动力学研究
Nuclear dynamics investigation of the initial electron transfer in the cyclobutane pyrimidine dimer lesion repair process by photolyases
摘要：
光解酶是能够收集阳光以修复由紫外线引起的DNA损伤的蛋白质。在这项工作中，我们专注于在修复过程中的第一步环丁烷嘧啶二聚体光产物（CPD）的病变，这是一个电子转移（ET）从黄素辅因子CPD，并研究在这一步中的各种核自由度（DOF）的作用。利用瞬态光谱对ET阶跃进行了实验研究，得到的数据为检验量子动力学模型的质量提供了很好的依据。基于以前的理论研究的电子结构和构象的蛋白质活性位点，我们提出了一个程序来建立一个非绝热哈密顿模拟ET反应的分子复合物模仿酶的活性位点。我们生成一个减少核维模型，提供了第一个非经验的量子动力学描述的结构特征影响ET率。通过改变模型中的核自由度参数化来评估不同核运动的作用，我们证明了低频黄素蝴蝶弯曲模式通过减少供体和受体状态之间的Franck-Condon重叠来减缓ET，并且还诱导退相干。
英文摘要：
Photolyases are proteins capable of harvesting the sunlight to repair DNA damages caused by UV light. In this work we focus on the first step in the repair process of the cyclobutane pyrimidine dimer photoproduct (CPD) lesion, which is an electron transfer (ET) from a flavine cofactor to CPD, and study the role of various nuclear degrees of freedom (DOF) in this step. The ET step has been experimentally studied using transient spectroscopy and the corresponding data provide excellent basis for testing the quality of quantum dynamical models. Based on previous theoretical studies of electronic structure and conformations of the protein active site, we present a procedure to build a diabatic Hamiltonian for simulating the ET reaction in a molecular complex mimicking the enzyme's active site. We generate a reduced nuclear dimensional model that provides a first non-empirical quantum dynamical description of the structural features influencing the ET rate. By varying the nuclear DOF parametrization in the model to assess the role of different nuclear motions, we demonstrate that the low frequency flavin butterfly bending mode slows ET by reducing Franck-Condon overlaps between donor and acceptor states and also induces decoherence.
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