SITE SELECTIVE EXAFS AND RIXS OF FE-ONLY HYDROGENASE AND RELATED MODELS

纯铁加氢酶的位点选择性 EXAFS 和 RIX 及相关模型

• 批准号: 7369147
• 负责人: Stephen P. Cramer
• 金额: $ 2.81万
• 依托单位: ILLINOIS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2007-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7369147
• 关键词: SITE; SELECTIVE; EXAFS; RIXS; FE

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. This proposal is part of our study on the critical metalloenzyme FeFe hydrogenase, and its mechanism of catalytic dihydrogen activation: 2H+ + 2e- = H2. We propose to use our high-resolution emission spectrometer on BioCAT to measure both site-selective EXAFS on purified enzyme as well as XES on simple inorganic "model" compounds. FeFe] H2ases are among the most efficient H2 catalysts known, with Kcat values up to 6000 H2 s-1 Despite the availability of excellent crystal structures and extensive spectroscopic study many questions about the molecular and electronic structure are still poorly understood. (1) What are the structural and conformational changes in the cluster during activation and catalysis?. (2) What are the oxidation states and spin-states of the dimeric Fe sub-sites. this more favorable towards hydrogen binding? If so how, and why? XES should allow us to resolve the oxidation state problem. Our previous on H-cluster models showed their low-spin Fe(I) nature, and that the valance region is sensitive to cluster oxidation state and/or the presence of a bridging CO. We propose to study further model compounds and extend the studies to purified protein, thus resolving the oxidation state issue. Site-selective EXAFS on purified protein should also help resolve the structural and conformational issues. As the cubane 4Fe are almost certainly high-spin, and the 2Fe subsite is low-spin, site-selective EXAFS should structurally characterize the expected dynamic changes of the low-spin 2Fe subsite separately from the 4Fe cubane.

该子项目是利用 NIH/NCRR 资助的中心拨款提供的资源的众多研究子项目之一。子项目和研究者 (PI) 可能已从另一个 NIH 来源获得主要资金，因此可以在其他 CRISP 条目中得到体现。列出的机构是中心的机构，不一定是研究者的机构。该提案是我们对关键金属酶 FeFe 氢化酶及其催化二氢活化机制：2H+ + 2e- = H2 研究的一部分。 我们建议使用 BioCAT 上的高分辨率发射光谱仪来测量纯化酶上的位点选择性 EXAFS 以及简单无机“模型”化合物上的 XES。 FeFe] H2ase 是已知最有效的 H2 催化剂之一，Kcat 值高达 6000 H2 s-1。尽管具有出色的晶体结构和广泛的光谱研究，但有关分子和电子结构的许多问题仍然知之甚少。 (1)簇在活化和催化过程中发生了哪些结构和构象变化？ (2) 二聚 Fe 子位点的氧化态和自旋态是什么？这更有利于氢结合？如果是的话，如何，为什么？ XES 应该能让我们解决氧化态问题。我们之前的 H 簇模型显示了它们的低自旋 Fe(I) 性质，并且价区对簇氧化态和/或桥接 CO 的存在敏感。我们建议进一步研究模型化合物并将研究扩展到纯化的蛋白质，从而解决氧化态问题。 对纯化蛋白质进行位点选择性 EXAFS 也应该有助于解决结构和构象问题。由于立方烷 4Fe 几乎肯定是高自旋的，而 2Fe 子位点是低自旋的，位点选择性 EXAFS 应该在结构上表征低自旋 2Fe 子位点与 4Fe 立方烷的预期动态变化。