SINGLE CRYSTAL XAS STUDIES ON O2 ACTIVATING HEME PROTEINS

O2 激活血红素蛋白的单晶 XAS 研究

• 批准号: 8362248
• 负责人: BRITT HEDMAN
• 金额: $ 2.19万
• 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/8362248
• 关键词: Binding; Complex; Coupled; Cytochrome c Peroxidase; Data; Electronics; Electrons; Funding; Grant; Heme; Hemeproteins; Hydrogen Peroxide; Light; Methemoglobin; Modeling; National Center for Research Resources; Oxyhemoglobin; Principal Investigator; Radiation; Research; Research Infrastructure; Resources; Signal Transduction; Solutions; Source; Spectrum Analysis; Superoxides; Sushi Domain; Time; Triplet Multiple Birth; United States National Institutes of Health; Water; cost; density; deoxyhemoglobin; electronic structure; structural biology; theories

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. We propose to investigate two heme proteins involved in O2 binding using solution and single crystal XAS spectroscopy. The first study will be on cytochrome c peroxidase, which catalyzes the two-electron reduction of H2O2 to water. The reduction of H2O2 proceeds via the formation of two high-valent heme intermediates; compound I and compound II. We plan to study compound I using single crystal Fe K-edge XAS and EXAFS to determine the rate of photoreduction and the concomitant change in the EXAFS signal (specifically the Fe-O bond). These studies will be extended to compound II of CCP to understand differences in the geometric and electronic structure between the two high-valent states. The XAS data will be coupled to DFT (density functional theory) and Fe K-pre-edge time dependent-DFT calculations, which will help shed light on the intermediates formed in the catalytic mechanism of H2O2 reduction by CCP. In the second study we propose to investigate the electronic structure of oxyhemoglobin using a combination of Fe K-pre-edge analysis and time-dependent DFT calculations. The data will be correlated to deoxyhemoglobin, methemoglobin and heme model complexes to accurately distinguish between the following possible electronic configurations of the [(heme)Fe-O2] species present in oxyhemoglobin: i) low-spin S=0 FeII + singlet S=0 O2, ii) an intermediate-spin S=1 FeII + triplet S=1 O2 (antiferromagnetically (AF) coupled) and iii) a lowspin S=1/2 FeIII + S=1/2 O2 - (superoxide).

该副本是利用资源的众多研究子项目之一 由NIH/NCRR资助的中心赠款提供。对该子弹的主要支持 而且，副投影的主要研究员可能是其他来源提供的 包括其他NIH来源。 列出的总费用可能 代表subproject使用的中心基础架构的估计量， NCRR赠款不直接向子弹或副本人员提供的直接资金。 我们建议使用溶液和单晶XAS光谱研究参与O2结合的两种血红素蛋白。第一项研究将是关于细胞色素C过氧化物酶的，该酶将H2O2的两电子还原催化为水。 H2O2的还原通过形成两个高价值血红素中间体而进行。化合物I和化合物II。我们计划使用单晶Fe K-gede XAS和EXAFS研究化合物I，以确定光元的速率和EXAFS信号（特别是Fe-O键）的伴随变化。这些研究将扩展到CCP的化合物II，以了解两个高价值状态之间几何和电子结构的差异。 XAS数据将与DFT（密度功能理论）和Fe K-Pre-gre-Edge时间相关的DFT计算耦合，这将有助于阐明CCP减少H2O2催化机理中的中间体。在第二项研究中，我们建议使用Fe K-Pre-Edge分析和时间依赖性的DFT计算的组合研究氧蛋白的电子结构。该数据将与脱氧血红蛋白，非母球蛋白和血红素模型复合物相关，以准确区分[（heme）Fe-o2]种类的以下可能的电子构型：oxyhemoglobin：i）低旋转s = 0 feii + Singlet S = 0 O2，II） （抗磁性（AF）耦合）和iii）lowspin s = 1/2 feIII + s = 1/2 O2-（超氧化物）。