TIME RESOLVED X-RAY SPECTROSCOPY OF PHOTOSYSTEM II

光系统 II 的时间分辨 X 射线光谱

• 批准号: 8362328
• 负责人: VITTAL YACHANDRA
• 金额: $ 1.87万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8362328
• 关键词: Binding Proteins; Biochemical; Charge; Chlorophyll; Complex; Coupled; Cyanobacterium; Detection; Electrons; Evolution; Funding; Grant; Label; Ligands; Membrane; Methods; National Center for Research Resources; Optics; Oxygen; Plants; Principal Investigator; Radiation; Reaction; Research; Research Infrastructure; Resources; Scanning; Source; Structure; Time; United States National Institutes of Health; Water; X ray spectroscopy; cost; density; insight; oxidation; photosystem II; protein complex; research study; structural biology

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Photosystem II (PS II) is a membrane-bound protein complex found in green plants and cyanobacteria, which catalyzes photosynthetic water oxidation and oxygen evolution. Single-electron photo-oxidations of a specialized chlorophyll molecule in the reaction center of PSII are coupled to the four-electron oxidation of water by the water-oxidizing complex (WOC). This complex is composed of four Mn and one Ca bridged by a number of oxygens (Mn4OXCa), and advances through five intermediate states labeled S0-S4 where each transition is completed in about 100 to 1400 ms. Although the WOC has been the subject of numerous biochemical and spectroscopic studies and the static structure has become more clearly resolved, the dynamic changes within the complex during the catalytic turnover and the mechanism of water oxidation remain largely unknown. Although some spectroscopic evidence for the existence of intermediate states, between the S3 and S0 states in the catalytic cycle, have been provided by UV/VIS and x-ray spectroscopic methods, no detailed x-ray spectroscopic characterization of the dynamics during each S-state transition has been undertaken yet. In this proposal we describe experiments for acquisition of time resolved spectra on PS II in the Mn K edge region (XANES) using a step scan approach and in the region of the K x-ray emission lines (XES), using a dispersive optics detection approach to collect the entire spectral information in one shot. We expect the present study will provide important insights into the changes of the charge density distribution and the Mn-ligand interactions within the Mn4OXCa complex during its catalytic cycle, providing conclusions about the possible mechanism of water oxidation and oxygen evolution.

这个子项目是许多利用资源的研究子项目之一 由NIH/NCRR资助的中心拨款提供。子项目的主要支持 而子项目的主要调查员可能是由其他来源提供的， 包括其他NIH来源。 列出的子项目总成本可能 代表子项目使用的中心基础设施的估计数量， NCRR赠款不直接向子项目或子项目工作人员提供资金。 光系统II（PS II）是存在于绿色植物和蓝藻中的一种膜结合蛋白复合物，它催化光合作用中的水氧化和放氧。在PSII的反应中心的一个专门的叶绿素分子的单电子光氧化耦合到水的四电子氧化的水氧化复合物（WOC）。这种复合物由四个Mn和一个Ca组成，由许多氧（Mn 4 OXCa）桥接，并通过五个标记为S 0-S4的中间状态，其中每个跃迁在约100至1400 ms内完成。在催化转换过程中络合物内的动态变化和水氧化的机理在很大程度上仍然未知。虽然一些光谱证据的存在的中间状态，S3和S 0状态之间的催化循环，已提供了UV/维斯和X-射线光谱方法，没有详细的X-射线光谱表征的动力学在每个S-状态的过渡尚未进行。在本提案中，我们描述了使用步进扫描方法在PS II上在Mn K边缘区域（XANES）中采集时间分辨光谱的实验，以及在K条x射线发射线（XES）区域中使用色散光学检测方法采集时间分辨光谱的实验。一次拍摄整个光谱信息。我们预计本研究将为了解Mn 4 OXCa复合物在催化循环过程中电荷密度分布和锰与配体相互作用的变化提供重要见解，并提供有关水氧化和析氧可能机制的结论。