膜环境中捕光天线蛋白的构型稳定性对仿生光电器件性能影响的理论模拟研究

Light-harvesting complexes 1 and 2 (LH1, LH2) absorb solar energy effectively and transfer exciton energy to reaction center (RC) very quickly to provide sufficient energy for the primary charge separation reaction; so, when used in the photoelectric conversion-relevant research, LH1 and LH2 can help to effectively improve the photocurrent electron density. The very recent experiments reported when the LH2-LH1-RC complexes are put in natural-lipid,they show highly extended photocurrent occurance time span but still keep high photoelectron-density. This is the new hope of the improvement of the efficiency of photoelectric conversion. Considering the existing experimental methods cannot explain the phonomena above, rational design of new photoelectric devices are, therefore, tethered.The current project will be initiated from precisely construct the 3D structure of LH2-LH1-RC complex. The stabilization of the conformation and properties of the complex by different of membranes will be analyzed and the influences of the properties of the membranes on the conformational changes of the protein complexes will be explianed. Furthermore, the mechanisms of the generation of the high photo-electron density and the elongation of the photo-current occurrence time span will be disclosed. Ideal membrane candidates that can help to improve photoelectric conversion efficiency will be suggested, which can be used to guide the rational design of noval photoelectric conversion experiments. Addtionally, the theoretical models in the current project could provide basic structural information for deep investigations of the excition energy transfer in LH1/2 and for the mechnism studies of the photoelectric conversion in RC.

捕光天线蛋白1，2（LH1，LH2）可高效收集太阳光能，并迅速将能量传至反应中心（RC），为原初电荷反应提供充足的能量。将LH1和LH2用于以RC为主体的光电转化研究中，可有效提高光电流密度。进一步实验表明，将LH2-LH1-RC置于天然膜中，可在维持高光电流密度的同时有效延长电流发生时间。这为有效提高器件的光电转化效率研究提供了新思路。但目前实验尚无法解释上述现象的机理，进一步合理设计光电器件因而受到限制。本项目拟从准确模建LH2-LH1-RC结构出发，通过分析不同类型的膜对蛋白的构像和性质稳定性作用，阐明膜对蛋白构型和构像变化的影响规律，进而揭示影响光电流密度的机理，并在此基础上提出有利于提高光电效率的理想膜类型，用于指导合理设计光电转化实验。此外，本项目的理论模型可为深入研究捕光天线内的能量传递和反应中心内部的光电转化机理提供初始结构信息。

捕光天线蛋白复合物II可高效收集太阳能，并迅速将能量相继传至捕光天线蛋白复合物I和反应中心，为原初电荷反应提供充足的能量。实验表明，紫细菌LH2蛋白的椭圆畸变会降低光电转化过程中的能量传递效率。本项目针对LH2-LH1-RC置于天然膜环境中有利于提高光电转化过程中的光电流密度机理尚不明确的具体问题，从准确模建捕光天线蛋白体系入手，以分子动力学为主要研究手段分析不同类型、不同厚度的膜对蛋白构象和性质稳定性影响规律。首先以拉伸动力学模拟捕光天线蛋白II由圆形到椭圆形的完整椭圆畸变过程，最终得到了离心率为0.45~0.68的合理椭圆构象；同时获得了在LH2发生椭圆畸变期间B850色素空间排列方式的变化过程；其次研究不同厚度膜环境和去污剂环境中LH2的椭圆型畸变构象变化，重点探讨椭圆形畸变过程中蛋白离心率的变化规律。从而揭示LH2椭圆畸变实验中存在问题以及定性描述了椭圆形畸变的内在原因。本项目对于指导合理设计光电转化实验和为深入研究捕光天线内的能量传递和反应中心内部的光电转化机理提供初始结构信息。