Structure and Function of Type I Reaction Centers: Photosystem I and Green Bacteria

要求提供支助，以调查 光合反应中心在光系统1和密切 相关的绿色硫细菌。 该项目将侧重于 FeS中心和醌类作为过渡中间体的作用 电子转移 闪光动力学光度法和EPR 光谱学将用作主要分析方法。 在 在绿色细菌的情况下，我们将重组受体侧 与已经表达的含有22 kDa FeS的多肽 在大肠杆菌 阐明了抑制的机制， 光系统1中的醌结合位点是重要的，因为 潜在的使用这个网站的一类新的除草剂。 一个关于光系统1的新项目已经启动， 核心异源二聚体的分子模拟研究。 劳顾会 已经测试了一个由模型产生的假设， 关于亚基PsaC与Fx结构域的相互作用 在核心异源二聚体中。 这将继续与一个 直接实验测试亮氨酸拉链基序的作用。 这将涉及含有基序的肽的合成， 研究它们的物理特性。 未来的实验将 通过合成设计的蛋白质来创建光系统1的模型 折叠成4-螺旋束和安装氧化还原中心 与螺旋间环中的光系统1相关。 这 该倡议将为今后的模型研究提供立足点 含有光敏成分的物质 %%% 植物和某些细菌的光合作用是通过 光与特殊色素的相互作用 金属蛋白复合物 复杂的组成部分和 金属，色素和蛋白质的定量分析将在 通过复杂的分析方法。 此外， 某些化合物与复合物的相互作用 作为设计除草剂的模型， 干扰光合作用。

Support is requested to investigate the structure and function of photosynthetic reaction centers in photosystem 1 and the closely related green sulfur bacteria. The project will focus on the role of FeS centers and quinones as transient intermediates in electron transfer. Flash kinetic spectrophotometry and EPR spectroscopy will be used as principle analytical methods. In the case of green bacteria we will reconstitute the acceptor side with a 22 kDa FeS containing polypeptide that has been expressed in E. coli. Elucidation of the mechanism of inhibition of the quinone binding site in Photosystem 1 is important because of the potential of using this site for a new class of herbicides. A new project has been initiated on Photosystem 1 following a molecular modeling study of the core heterodimer. The lab has already tested one hypothesis generated by the modeling concerning the interaction of the subunit PsaC with the Fx domain in the core heterodimer. This will be continued together with a direct experimental test of the role of the leucine zipper motif. This will involve synthesis of peptides containing the motif and studying their physical properties. Future experiments will create models of Photosystem 1 by synthesizing designed proteins that fold into 4-.-helical bundles and installing redox centers of relevance to Photosystem 1 in the interhelical loops. This initiative will provide footholds for future studies of models that would contain photoactive components. %%% Photosynthesis is accomplished in plant and certain bacteria by the interaction of light with specialized pigment containing metal-protein complexes. The components of the complex and the ration of metal, pigment, and protein are to be analyzed in the proposal by sophisticated analytical methods. Also, the nature of the interaction of certain chemical compounds with the complex is important as a model for the design of herbicides that can interfere with photosynthesis.