膜蛋白光系统I（Photosystem I）的超滤分离过程研究

光合膜蛋白是整合于光合膜上的色素蛋白复合物，在光合作用的电子传递中发挥着重要作用。因此，在分子水平上揭示各种光合膜蛋白的结构与功能及其相互关系，对揭示光合作用光能转化的机理具有重要意义。但由于光合膜蛋白的传统提取工艺耗时较长、制备量有限，且光合膜蛋白的稳定性较差，这使得光合膜蛋白的提取技术已成为研究其结构与功能的主要瓶颈之一。.本研究拟选择光系统I（PSI）作为光合膜蛋白的代表，在初步实现其超滤分离的基础上，利用原子力显微镜、圆二色光谱仪等现代分析手段，系统研究超滤工艺对目标蛋白PSI和杂蛋白PSII（光系统II）结构性质的影响；分析超滤膜的孔径分布及表面带电性质等；探讨影响PSI膜分离过程的主要机理；建立膜蛋白结构特性与超滤工艺参数选择之间的关系；通过对PSI膜分离过程的放大研究，实现其规模化制备，为PSI结构生物学及相关应用研究提供物质基础，并为其他种类膜蛋白的超滤提取提供科学依据。

The thylakoid membrane proteins belong to the photosynthetic pigment-protein complexes, which play a central role in the electron transfer during the course of photosynthesis. Therefore, it is of great importance for us to explore the mechanisms of photosynthesis by studying the structures and functions of the membrane proteins at the molecular level. However, the conventional techniques to isolate the thylakoid membrane proteins suffer from long time-consuming and low-yield rate. Thus, the isolation process has become one of the bottle-neck problems to study the structures and functions of the thylakoid membrane proteins..In the present project, photosystem I (PSI) is chosen as the target thylakoid membrane protein. After being isolated from spinach using ultrafiltration, it will be characterized by using modern analysis methods (such as atomic force microscopy imaging, circular dichroism, etc.) to study the effects of ultrafiltration operating parameters on the properties of PSI. In addition, the properties of membranes (such as pore size distribution, isoeletric point, etc.) and photosystem II (impurity protein) will be also examined. On the basis of all the anaysis results, the mechanisms of PSI isolation using ultrafiltration will be explored. Further work on PSI production on a large scale will be also studied. The performance of this project will not only provide sufficient PSI samples for the biological research, but also offer an novel opportunity in theory for the isoaltion of other kinds of membrane proteins using ultrafiltration.