HALIDE XAS STUDIES OF PHOTOSYNTHETIC WATER OXIDATION COMPLEX

光合水氧化复合物的卤化物XAS研究

• 批准号: 6119601
• 负责人: MELVIN P KLEIN
• 金额: --
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-01 至 2000-04-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6119601
• 关键词: Fungi; biomaterials; plants; proteins; structural biology

Photosynthetic water oxidation is catalyzed by a cluster of 4 Mn atoms. Chloride and calcium are essential cofactors for oxygen evolution activity. It has been postulated that halide is a ligand to Mn, but the evidence at present is not conclusive. Cl K-edge studies by Hedman et al have shown that there is a distinctive pre-edge feature in the K-edge spectrum of Cl when it is a ligand to transition metals. The feature was assigned to a Cl 1s to metal 3d transition, which becomes allowed due to mixing with empty d-orbitals. Such a pre-edge feature is present only when Cl- is ligated to a metal with empty d-orbitals. We propose to collect Cl K-edge spectra of photosystem II samples containing only the minimal amount of Cl-required (1Cl/4Mn) for activity to determine whether Cl is ligated to Mn.

光合水氧化由 4 Mn 簇催化 原子。 氯和钙是氧气的重要辅助因子 进化活动。 据推测，卤化物是配体 嗯，但目前的证据还不是决定性的。 Cl K 边缘研究 Hedman 等人的研究表明，存在独特的前边缘 当 Cl 作为过渡配体时，其 K 边光谱中的特征 金属。 该特征被分配给 Cl 1s 到金属 3d 的转变， 由于与空 d 轨道混合，这变得被允许。 这样一个 仅当 Cl- 连接至金属时，才会出现前边缘特征 空 d 轨道。 我们建议收集 Cl K 边缘光谱 光系统 II 样品仅含有最少量的 确定 Cl 是否连接的活性需要 Cl (1Cl/4Mn) 至锰。