Electron Flow in Photosynthetic Bacteria

本项目的具体目标是：(1)利用共振拉曼光谱对光合作用的紫色非硫细菌的细胞色素bc1配合物进行表征，并对配合物上醌的结合位点进行表征；(2)比较紫色硫菌与紫色非硫菌中细胞色素bc1复合物及其可溶性细胞色素c电子受体。还比较了这些细胞色素bc1复合物与功能类似的叶绿体细胞色素b6f复合物的光谱特性。重点放在这些细菌中生物能量学的独特方面或与线粒体呼吸类似的细菌相比，这些细菌过程的简单性。若干光谱学（如共振拉曼光谱和电子顺磁共振光谱）、生化(如将利用特定氨基酸的化学修饰和光亲和标记和遗传技术，试图在分子水平上提供这些电子转移反应的细节，这些电子转移反应是光合细菌能量转导的核心。细胞代谢所需的能量是通过几种不同的机制产生的。在这项研究中，电子传递与电化学梯度将研究光合细菌。这是一个方便的实验系统，因为电子转移可以通过打开或关闭灯来启动和停止。

The specific objectives of this project are (1) to characterizethe cytochrome bc1 complex of a photosynthetic purple non-sulfur bacterium by resonance Raman spectroscopy and to characterize the binding sites on the complex for quinone, cytochrome c2 and the inhibitor antimycin A and (2) to compare the cytochrome bc1 complex and its soluble cytochrome c electron acceptor in apurple sulfur bacterium with those of purple non-sulfur bacteria. Also to compare the spectroscopic properties of these cytochrome bc1 complexes with the functionally analogous chloroplast cytochrome b6f complex. Emphasis is placed on unique aspects of bioenergetics in these bacteria or on the simplicity of processes in these bacteria compared to the analogous one in mitochondrial respiration. A number of spectroscopic (e.g., resonance Raman and electron paramagnetic resonance spectroscopy), biochemical (e.g., chemical modification of specific amino acids and photoaffinity labeling) and genetic techniques will be utilized in an attempt to provide details at the molecular level about these electron transfer reactions that are central to energy transduction in photosynthetic bacteria. %%% The energy needed for cell metabolism is generated through several different mechanisms. In this study, electron transport linked to an electrochemical gradient will be studied in a photosynthetic bacterium. This is a convenient experimental system because electron transfer can be started and stopped by turning light on or off.