X-RAY SPECTROSCOPY OF PHOTOSYSTEM II SINGLE CRYSTALS

PHOTOSYSTEM II 单晶的 X 射线光谱

• 批准号: 7954198
• 负责人: VITTAL YACHANDRA
• 金额: $ 2.82万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7954198
• 关键词: Binding Proteins; Biochemical; Charge; Chemistry; Chlorophyll; Complex; Computer Retrieval of Information on Scientific Projects Database; Coupled; Cyanobacterium; Dependence; Electronics; Electrons; Environment; Evolution; Funding; Grant; Institution; Label; Membrane; Methods; Modeling; Mono-S; Nature; Oxygen; Plants; Property; Protein Binding; Reaction; Research; Research Personnel; Resources; Roentgen Rays; Site; Source; Structure; Techniques; United States National Institutes of Health; Water; X ray spectroscopy; dichroism; insight; oxidation; photosystem II; protein complex; research study; structural biology; synchrotron radiation; vector

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 are coupled to the four-electron oxidation of water by the oxygen-evolving complex (OEC) in PS II through five intermediate states labeled SO-S4. A protein-bound complex of four Mn atoms is thought to be the site of water oxidation chemistry and to function in charge accumulation. Although this Mn complex has been the subject of numerous biochemical and spectroscopic studies, the exact structure of the complex and the mechanism of water oxidation remain unknown. Although X-ray spectroscopic methods have been perhaps the most informative technique used to derive detailed information about the oxidation states of and the environment surrounding Mn in the OEC most of the X-ray spectroscopic studies were performed on randomly oriented PS II membranes; thus, no angle dependence of EXAFS features was observed. The ability to exploit the plane-polarized nature of synchrotron radiation has made possible the study of dichroism in oriented PS II membranes, mostly, in terms of the orientation dependence of the Mn-Mn vectors in the di-¿-oxo and mono-¿-oxo bridged Mn2 motifs that have been shown to be present in the OEC. In this proposal we describe experiments with single crystals of Mn model compounds and photosystem II. We expect the present study will provide important insights to the structure of the Mn complex and its electronic properties that are critical for understanding the mechanism of water oxidation and oxygen evolution.

该副本是使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，这是调查员的机构。 光系统II（PS II）是在绿色植物和蓝细菌中发现的一种膜结合的蛋白质复合物，可催化光合水的氧化物和氧气进化。反应中心中专门的叶绿素分子的单电子光氧化与PS II中的氧气进化复合物（OEC）偶联，直到五个标记为SO-S4的中间状态。尽管这种MN复合物已成为许多生化和光谱研究的主题，但据认为，蛋白质结合的四个原子的蛋白质结合复合物仍然未知。尽管X射线光谱方法可能是用于获取OEC中MN氧化态和周围环境的详细信息的最有用的技术，大多数X射线光谱研究是在随机定向的PS II机制上进行的；因此，未观察到EXAFS特征的角度依赖性。探索同步子辐射的平面偏振性质的能力使得在定向PS II机制中研究了二科运动，主要是根据Mn-Mn向量在di-oxo和mono-oxo-oxo-oxo-oxo-oxo-oxo-oxo-ox bridged的MN2基序中的方向依赖性而言。在此提案中，我们描述了MN模型化合物和光系统II的单晶实验。我们预计本研究将为MN复合物的结构及其电子特性提供重要的见解，这对于理解水氧化和氧气的机理至关重要。