EXAFS SPECTROSCOPIC STUDIES OF THE NIFE 'C-CLUSTER' IN CARBON MONOXIDE DEHYDROGE

一氧化碳脱氢中 NIFE“C 簇”的 EXAFS 光谱研究

• 批准号: 7598020
• 负责人: SIMON J GEORGE
• 金额: $ 0.56万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-03-01 至 2008-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7598020
• 关键词: Active Sites; Bacteria; Binding; Bioinorganic Chemistry; Carbon; Carbon Dioxide; Carbon Monoxide; Carbon monoxide dehydrogenase; Chemistry; Computer Retrieval of Information on Scientific Projects Database; Data; Development; Enzymes; Funding; Grant; Heterogeneity; Institution; Lead; Process; Research; Research Personnel; Resources; Sampling; Site; Source; Spectrum Analysis; Structure; System; Transition Elements; United States National Institutes of Health; Variant; X-Ray Crystallography; catalyst; novel; oxidation

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. The bacteria R. rubrum (Rr) and C. hydrogenoformans (Ch) contain a Ni carbon monoxide dehydrogenase (CODH) that enables them to grow on CO as their sole carbon source. The active site of Ni CODH is the so-called 'C-cluster' a novel Ni-Fe-S center that catalyzes the oxidation of CO to CO2. Recent X-ray crystallography has shown the 'C-cluster' to comprise a Ni coordinated to a FeS4 unit, bridged to an external Fe site. This was a surprise, as prior EXAFS analysis had excluded a symmetric NiFeS4 unit. However, the various 'C-cluster' crystal structures show significant differences with each other, and, they also show evidence of cluster heterogeneity within a given crystal. We have recent EXAFS data that shows evidence of cluster re-arrangement on reduction and/or CO binding. The implication is that the cluster structure dynamically rearranges, either as part of an "activation" process, or as part of its catalytic mechanism. We propose to use EXAFS to investigate the structural changes of the 'C-cluster' sites for Rr and Ch CODH. This is part of a comprehensive spectroscopic study on the C-cluster. We plan to study enzyme that has been: reductively poised; CO-bound and inhibited. We have available variants of Rr CODH where active site residues have been modified, one where the external Fe is deleted. We also have Co-CODH and Zn-CODH, where the Ni has been replaced by another transition metal. We are confident that, using other spectroscopies such as EPR, FT-IR and resonance Raman as controls, we can prepare homogeneous C-cluster samples for EXAFS analysis. This should enable us to parameterize the C-cluster structural dynamics and from there understand the underpinning cluster chemistry and eventually the catalytic cycle of this biologically important enzyme system. In addition, the novel bioinorganic chemistry uncovered could well lead to the development of novel catalysts.

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。子项目和 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。 细菌 R. rubrum (Rr) 和 C. Hydronoformans (Ch) 含有 Ni 一氧化碳脱氢酶 (CODH)，使它们能够以 CO 作为唯一碳源生长。 Ni CODH 的活性位点是所谓的“C 簇”，是一种新型 Ni-Fe-S 中心，可催化 CO 氧化为 CO2。最近的 X 射线晶体学显示“C 簇”包含与 FeS4 单元配位的 Ni，桥接至外部 Fe 位点。这是一个惊喜，因为之前的 EXAFS 分析已排除对称 NiFeS4 单元。然而，各种“C 簇”晶体结构彼此之间表现出显着差异，并且它们还显示出给定晶体内簇异质性的证据。我们最近的 EXAFS 数据显示了还原和/或 CO 结合的簇重新排列的证据。这意味着簇结构动态地重新排列，或者作为“激活”过程的一部分，或者作为其催化机制的一部分。我们建议使用 EXAFS 研究 Rr 和 Ch CODH 的“C 簇”位点的结构变化。这是 C 星团综合光谱研究的一部分。我们计划研究具有以下特征的酶： 还原平衡； CO 结合并受到抑制。我们有可用的 Rr CODH 变体，其中活性位点残基已被修饰，其中外部 Fe 被删除。我们还有 Co-CODH 和 Zn-CODH，其中 Ni 已被另一种过渡金属取代。我们相信，使用 EPR、FT-IR 和共振拉曼等其他光谱作为对照，我们可以制备均匀的 C 簇样品用于 EXAFS 分析。这应该使我们能够参数化 C 簇结构动力学，并从那里了解基础簇化学，并最终了解这个生物学上重要的酶系统的催化循环。此外，所发现的新型生物无机化学很可能导致新型催化剂的开发。