X-RAY EMISSON SPECTROSCOPY OF THE PHOTOSYNTHETIC MN4CA COMPLEX

光合 MN4CA 复合物的 X 射线发射光谱

• 批准号: 8170038
• 负责人: VITTAL YACHANDRA
• 金额: $ 5.29万
• 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/8170038
• 关键词: Address; Aerobic; Algae; Chloride Ion; Chlorides; Complex; Computer Retrieval of Information on Scientific Projects Database; Cyanobacterium; Detection; Development; Electronics; Funding; Future; Grant; Heart; Institution; Life; Ligands; Methods; Natural regeneration; Oxygen; Plants; Process; Raman Spectrum Analysis; Reaction; Research; Research Personnel; Resolution; Resources; Roentgen Rays; Role; Site; Source; Spectrum Analysis; Structure; Techniques; United States National Institutes of Health; Vision; Water; X ray spectroscopy; absorption; catalyst; electronic structure; emission spectroscopy; improved; oxidation; photosystem II; planetary Atmosphere; 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. Oxygen, that supports all aerobic life, is abundant in the atmosphere because of its constant regeneration by photosynthetic water oxidation by green plants, algae and cyanobacteria. This light-requiring reaction is catalyzed by a Mn4Ca cluster associated with photosystem II (PS II). Given the role of PS II in maintaining life on the biosphere and the future visions of a renewable energy economy, it is vital to elucidate the structure and mechanism of the Mn4Ca catalyst, which is sometimes referred to as the ?heart? of the water oxidation process. Although, the electronic and geometric structure of the Mn4Ca water-splitting catalyst has been extensively investigated, the precise structure and mechanism of this catalyst has so far eluded all attempts of determination by x-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) and other spectroscopic techniques. The development of new methods of high resolution absorption and emission x-ray spectroscopy, including x-ray Raman spectroscopy, range-extended EXAFS and site-selective X-ray spectroscopy are critical for providing important new information, that will help in elucidating not only the structure of the complex, but also the mechanism of the photosynthetic water oxidation process. The present proposal builds on the past experiments and addresses some new applications of x-ray emission spectroscopy to the Mn complex in PS II as follows: a) X-ray Raman or RIXS spectroscopy that will address the electronic structure of the Mn complex, b) Kbeta emission and site selective spectroscopy that will selectively probe different Mn sites or different oxidation states in the Mn complex, c) High resolution Mn Kalpha detection of EXAFS that will allow us to collect EXAFS beyond the Fe K-edge thus improving resolution and d) Interatomic Mn Kbeta2,5 spectra that will be a probe for the ligand atoms of Mn, especially to ascertain whether chloride is a ligand of Mn in PS II.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目及 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 支持所有有氧生命的氧气在大气中含量丰富，因为绿色植物、藻类和蓝细菌通过光合水氧化不断再生氧气。这种需光反应由与光系统 II (PS II) 相关的 Mn4Ca 簇催化。鉴于 PS II 在维持生物圈生命方面的作用以及可再生能源经济的未来愿景，阐明 Mn4Ca 催化剂（有时被称为“心脏”）的结构和机制至关重要。水的氧化过程。尽管 Mn4Ca 水分解催化剂的电子和几何结构已被广泛研究，但该催化剂的精确结构和机理迄今为止尚未通过 X 射线衍射（XRD）、扩展 X 射线吸收精细测定来确定。结构（EXAFS）和其他光谱技术。高分辨率吸收和发射 X 射线光谱新方法的开发，包括 X 射线拉曼光谱、增程 EXAFS 和位点选择性 X 射线光谱对于提供重要的新信息至关重要，这不仅有助于阐明该复合物的结构，也是光合水氧化过程的机制。本提案建立在过去的实验基础上，并解决了 X 射线发射光谱在 PS II 中 Mn 配合物中的一些新应用，如下：a) X 射线拉曼或 RIXS 光谱，将解决 Mn 配合物的电子结构，b ) Kbeta 发射和位点选择性光谱，将选择性地探测 Mn 络合物中的不同 Mn 位点或不同氧化态，c) EXAFS 的高分辨率 Mn Kalpha 检测，这将使我们能够收集超出 Fe K 边缘的 EXAFS，从而提高分辨率和 d ）原子间 Mn Kbeta2,5 光谱将作为 Mn 配体原子的探针，特别是确定氯是否是 PS II 中 Mn 的配体。