Protein electron transfer reorganization energy spectrum from normal mode analysis. 1. Theory
Protein electron transfer reorganization energy spectrum from normal mode analysis. 1. Theory
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DOI：
10.1021/jp9728464
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发表时间：
1998-03-12
影响因子：
3.3
通讯作者：
Go, N
中科院分区：
文献类型：
--
作者：
Basu, G;Kitao, A;Go, N
我们提出了一个描述蛋白质波动与电子转移耦合的分析模型，该模型将蛋白质和本体溶剂都处理为电子转移耦合，蛋白质由包含显式蛋白质原子的低介电腔表示，而本体溶剂由围绕腔的高介电连续体表示。蛋白质波动由集体正态模式模拟，通过显式反应场能纳入溶剂化能。假设在法模矢量空间中的超平面上电子转移前后势能面之差，计算了电子转移时平衡态法模变量与特定模式耦合和重组能相关的位移。这种线性耦合假设只允许一组法向模向量跨越反应物和生成物的平衡构象。该模型等效于简化的自旋玻色子形式（仅限蛋白质）；然而，与之前在这种形式主义中的工作不同，在我们的处理中，浴模不是空间匿名的。它们与明确的频率和空间特征相关联，允许蛋白质重组能量的光谱分析与实际蛋白质波动的一对一联系。我们的模型的这一方面是非常重要的，因为它第一次允许在实际的蛋白质运动和电子转移之间建立直接联系，正如在随附的论文中提出的模拟所证明的那样(J. Phys。化学，1998,102，XXX)。
We present an analytical model that describes the coupling of protein fluctuations to electron transfer, The model treats both the protein and the bulk solvent to couple to electron transfer, The protein is represented by a low-dielectric cavity containing explicit protein atoms, and the bulk solvent is represented by a high-dielectric continuum surrounding the cavity. Protein fluctuations are modeled by collective normal modes with solvation energies incorporated through explicit reaction field energies. The shifts of the equilibrium normal mode variables upon electron transfer, related to the mode-specific couplings and reorganization energies, are calculated assuming the difference of the potential energy surfaces before and after electron transfer by a hyper plane in the normal mode vector space. This linear coupling assumption allows only one set of normal mode vectors to span both the reactant and product equilibrium conformations. The model is equivalent to a reduced spin-boson formalism (protein only); however, unlike previous work within this formalism, the bath modes are not spatially anonymous in our treatment. They are associated with unambiguous frequency and spatial signatures allowing a spectral analysis of protein reorganization energy with one-to-one connection with actual protein fluctuation. This aspect of our model is very crucial since it allows, for the first time, to make a direct connection between actual protein motion and electron transfer, as demonstrated by a simulation presented in an accompanying paper (J. Phys. Chem. 1998, 102, XXX).