CRYSTALLOGRAPHIC STUDY OF PHOTOSYNTHETIC REACTION CENTER

该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 Rhodoptera sphaeroides R-26的单晶研究， 蛋白质复合物通过X射线衍射。 反应中心是内在的 进行光合作用初始步骤的膜蛋白 分居 中华民国类球形反应中心（Mr约100，000） 含有三种蛋白质亚基，四种细菌叶绿素， bacteriophenophytins，两个泛醌，和一个nonheme铁。 我们已经成长 反应中心的单晶，其反应速率超过3 埃分辨率，从而使结构的测定在原子 解决可能。 我们计划用常规的 晶体学方法 中华民国spheroides反应中心将作为一个模型系统，研究如何 跨膜电子传递耦合到膜的产生 潜力 这一反应中心已被广泛研究，通过两个 光谱和生物化学方法。 反应中心络合物是 因此，我们将有一个独特的机会， 关联光谱结果与三维结构的 复杂. 这一研究将有助于了解 膜蛋白 中华民国spharoides反应中心只是三个反应中心之一 高度有序晶体的可用性 使详细结构的确定成为可能。 的相关性 其氨基酸序列的三维结构会增加 膜蛋白的数据库，从而显著增强结构 这些类型的蛋白质的预测工作。

The aim of this project is to determine the detailed molecular structure of the photosynthetic reaction center from the photosynthetic bacterium Rhodopseudomonas sphaeroides R-26 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 R. sphaeroides reaction center (Mr about 100,000) contains three protein subunits, four bacteriochlorophylls, two bacteriophenophytins, two ubiquinones, and one nonheme iron. We have grown single crystals of the reaction center, which diffract to beyond 3 angstroms resolution, thus making the determination of structure at atomic resolution possible. We plan to determine structure by using conventional crystallographic methods. The R. spheroides reaction center will serve as 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 will 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 R. spharoides reaction center is only one of three 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 data base for membrane proteins, thereby markedly enhancing structure prediction efforts for these types of proteins.