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: 8170332
• 负责人: VITTAL YACHANDRA
• 金额: $ 0.34万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8170332
• 关键词: Binding Proteins; Biochemical; Charge; Chlorophyll; Complex; Computer Retrieval of Information on Scientific Projects Database; Coupled; Cyanobacterium; Detection; Electrons; Evolution; Funding; Grant; Institution; Label; Ligands; Membrane; Methods; Optics; Oxygen; Plants; Reaction; Research; Research Personnel; Resources; Scanning; Source; Spectrum Analysis; Structure; Time; United States National Institutes of Health; Water; density; insight; oxidation; photosystem; photosystem II; protein complex; research study

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. 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.

该副本是利用众多研究子项目之一 由NIH/NCRR资助的中心赠款提供的资源。子弹和 调查员（PI）可能已经从其他NIH来源获得了主要资金， 因此可以在其他清晰的条目中代表。列出的机构是 对于中心，这不一定是调查员的机构。 光系统II（PS II）是一种在绿色植物和蓝细菌中发现的膜结合的蛋白质复合物，可催化光合水氧化和氧气进化。 PSII反应中心中专门的叶绿素分子的单电子光氧化与水氧化复合物（WOC）耦合到水对水的四电子氧化。该复合物由多个氧气（MN4OXCA）桥接的四个MN和一个CA组成，并通过标记为S0-S4的五个中间状态进行进展，其中每个过渡在大约100至1400毫秒内完成。尽管WOC已成为众多生化和光谱研究的主题，并且静态结构已经更加清晰地解决了，但是在催化转移期间复合物内部的动态变化以及水氧化的机制仍然在很大程度上未知。尽管通过UV/VIS/VIS和X射线光谱方法提供了一些中间状态存在的光谱证据，但在催化周期中的S3和S0状态之间存在一些详细的X射线光谱表征，但在每个S状态过渡过程中尚无详细的X射线光谱表征。在此提案中，我们使用分散光学检测方法在此提案中描述了Mn K边缘区域（XANES）在Mn K边缘区域（XANES）中获取时间分辨光谱的实验。我们预计，本研究将为MN4OXCA复合物在其催化周期内的电荷密度分布的变化以及MN配体相互作用的变化提供重要的见解，从而得出了有关水氧化和氧气进化的可能机制的结论。