CRYSTALLOGRAPHIC STUDY OF PHOTOSYNTHETIC REACTION CENTER

这个项目的目的是确定详细的分子结构 来自光合细菌的光合作用反应中心 球形红假单胞菌R-26单晶的研究 通过X-射线衍射法分析蛋白质复合体。反应中心是内在的 执行光合作用电荷初始步骤的膜蛋白 分居。球形R.sphaeroides反应中心(Mr约10万) 含有三个蛋白质亚基，四个细菌叶绿素，两个 细菌酚类、两种泛醌和一种非血红素铁。我们已经成长了 反应中心的单晶，衍射率超过3 埃分辨率，从而使原子结构的测定 可能会有解决办法。我们计划通过使用常规方法来确定结构 结晶学方法。 球状杆菌反应中心将作为一个模型系统来研究 跨膜电子传递与膜的产生是耦合的 潜力。这个反应中心已经被广泛地研究过了 光谱和生化方法。反应中心复合体是 因此，我们将有一个独特的机会来 将光谱结果与分子的三维结构联系起来 很复杂。 这一研究将有助于对汉语句式结构的理解 膜蛋白。斯氏杆菌反应中心只是三个中心之一 膜蛋白的高度有序晶体的可用性 使详细结构的确定成为可能。的关联性。 其具有三维结构的氨基酸序列将增加 膜蛋白数据库，从而显著增强结构 对这些类型的蛋白质的预测努力。

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.