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资助的中心赠款提供的资源的许多研究子项目之一。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。列出的机构适用于该中心，这不一定是调查员的机构。该建议是我们关于临界金属酶FEFE氢化酶的研究的一部分，以及其催化二氢激活的机理：2H + + 2e- = H2。 我们建议使用BioCat上的高分辨率发射光谱仪在纯化的酶以及简单无机“模型”化合物上的XES上测量两个位点选择性EXAF。 FEFE] H2ase是已知的最有效的H2催化剂之一，尽管具有出色的晶体结构和广泛的光谱研究，但KCAT值高达6000 H2 S-1，但许多有关分子和电子结构的问题仍然知之甚少。 （1）激活和催化过程中簇的结构和构象变化是什么？ （2）二聚体Fe子站点的氧化态和自旋态是什么。这对氢结合更有利吗？如果是这样，为什么？ XES应该使我们能够解决氧化状态问题。我们先前在H群集模型上显示了其低旋转Fe（I）性质，并且Valance区域对簇氧化态和/或桥接CO的存在敏感。我们建议研究进一步的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。 对纯化蛋白质的现场选择性EXAF也应有助于解决结构和构象问题。由于古巴4FE几乎可以肯定是高旋转的，并且2FE亚铁矿是低旋转的，因此现场选择性EXAF在结构上应表征与4FE Cubane分开的低旋转2FE子站点的预期动态变化。