CRYSTALLOGRAPHIC STUDY OF PHOTOSYNTHETIC REACTION CENTER

这个项目的目的是确定详细的分子结构 光合细菌的光合反应中心 球形红细菌通过研究这种蛋白质的单晶 通过X-射线衍射测定复合物。 反应中心是内在的 进行光合作用初始步骤的膜蛋白 电荷分离 Rb。类球形反应中心（Mr = 约100，000）含有三个蛋白质亚基，四个 细菌叶绿素，两种细菌表叶绿素，两种泛醌，一种 类胡萝卜素和一种非血红素铁 我们将继续完善 从R-26反应中心的结构，并将它与其他 反应中心结构 我们将开始确定结构， 反应中心已经通过位点特异性 诱变 我们计划用常规的 晶体学方法 Rb。sphaeroides反应中心是一个研究的模型系统 跨膜电子传递是如何与 膜电位 这个反应中心已经被广泛研究 通过光谱学和生物化学的方法。 反应中心 复合物在晶体中起作用;因此，我们有一个独特的 有机会将光谱结果与三维 复杂的结构。 这一研究将有助于了解 膜蛋白 Rb。sphaeroides反应中心只是一个 一些膜蛋白，其中高度有序的可用性 晶体使得确定详细结构成为可能。 的 其氨基酸序列与三维结构的相关性 结构将增加膜蛋白的数据库，从而 显著增强了这些类型的结构预测工作， proteins.

The aim of this project is to determine the detailed molecular structure of the photosynthetic reaction center from the photosynthetic bacterium Rhodobacter sphaeroides by studying single crystals of this protein complex through x-ray diffraction. Reaction centers are intrinsic membrane proteins that carry out the initial steps in photosynthetic charge separations. The Rb. sphaeroides reaction center (Mr equals approximately 100,000) contains three protein subunits, four bacteriochlorophylls, two bacteriophenophytins, two ubiquinones, one carotenoid, and one nonheme iron. We will continue to refine the structure of the reaction center from R-26 and will compare it to other reaction center structures. We will start structure determinations on reaction centers that have been altered through site-specific mutagenesis. We plan to determine structures by using conventional crystallographic methods. The Rb. sphaeroides reaction center serves a model system to study how transmembrane electron transport is coupled to the production of membrane potential. This reaction center has been studied extensively through both spectroscopic and biochemical methods. The reaction center complex is functional in the crystal; therefore, we have a unique opportunity to correlate spectroscopic results with the three-dimensional structure of the complex. This study will contribute to the understanding of the structure of membrane proteins. The Rb. sphaeroides reaction center is only one of a few membrane proteins for which the availability of highly ordered crystals makes the determination of detailed structure possible. The correlation of its amino acid sequence with the three-dimensional structure will increase the database for membrane proteins, thereby markedly enhancing structure prediction efforts for these types of proteins.