ELECTRONIC STRUCTURE OF IRON ENZYME INTERMEDIATES FROM HIGH-RESOLUTION RIXS

高分辨率 RIX 中铁酶中间体的电子结构

• 批准号: 8362322
• 负责人: EDWARD I SOLOMON
• 金额: $ 2.66万
• 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/8362322
• 关键词: Chemistry; Energy Transfer; Enzymes; Funding; Goals; Grant; Heme; Hydrogen Bonding; In Situ; Iron; Life; Ligands; Metals; Methane hydroxylase; Methods; Modeling; Monitor; National Center for Research Resources; Photons; Principal Investigator; Process; Radiation; Research; Research Infrastructure; Resolution; Resources; Shapes; Source; Spectrum Analysis; Theoretical model; Time; United States National Institutes of Health; Vacuum; cost; electronic structure; multiplet; research study; structural biology; tool

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. The goal of the proposed research is to develop 1s2p resonant inelastic x-ray scattering (RIXS) as a general and quantitative tool for studying enzyme intermediates. We have previously used metal L-edge spectroscopy at SSRL to extend the concept of metal-ligand covalency by showing that the L-edge band shape can be used to quantify interactions between ligands and metal d-orbitals of different symmetry, i.e., differential orbital covalency (DOC). The DOC method allows for experimental determination of basic concepts in chemistry. However, metal L-edge spectroscopy is performed with soft x-rays in ultra-high vacuum and cannot in general be used for enzyme intermediates. 1s2p RIXS involves excitation from 1s 3d (h ~ 7.1 keV) and monitoring of the subsequent 2p 1s photon emission (h2 ~ 6.4 keV). The final state in this resonance process is 2p53dn+1, the same final state as for the L-edge experiment. 1s2p RIXS uses hard x-rays and does not require ultra-high vacuum, and can therefore be used to obtain L-edge-like spectra under in situ conditions. Our new contribution is a quantitative analysis of RIXS spectra in the energy transfer (h - h2) direction using the DOC analysis. The long life time of the 2p hole results in a sharp and feature-rich spectrum that can be accurately fitted using a parameterized multiplet model that includes configuration interaction. The electronic structure, including the DOC, is subsequently extracted from the theoretical model. The method will be used to study high-valent enzyme intermediates that activate inert C?H bonds; heme compounds I and II, the non-heme ferrryl-oxo intermediate in SyrB2 and intermediate Q in the binuclear iron enzyme methane monooxygenase. RIXS provides a new tool to investigate the requirements for C?H bond activation, but also to explain differences in reactivity between heme and non-heme enzymes.

该子项目是利用资源的众多研究子项目之一 由 NIH/NCRR 资助的中心拨款提供。子项目的主要支持 并且子项目的主要研究者可能是由其他来源提供的， 包括其他 NIH 来源。 子项目可能列出的总成本 代表子项目使用的中心基础设施的估计数量， NCRR 赠款不直接向子项目或子项目工作人员提供资金。 本研究的目标是开发 1s2p 共振非弹性 X 射线散射 (RIXS) 作为研究酶中间体的通用定量工具。我们之前在 SSRL 使用金属 L 边光谱来扩展金属-配体共价性的概念，表明 L 边带形状可用于量化配体和不同对称性金属 d 轨道之间的相互作用，即微分轨道共价键（DOC）。 DOC 方法允许通过实验确定化学中的基本概念。然而，金属 L 边光谱是在超高真空下使用软 X 射线进行的，通常不能用于酶中间体。 1s2p RIXS 涉及从 1s 3d (h ~ 7.1 keV) 激发并监测随后的 2p 1s 光子发射 (h2 ~ 6.4 keV)。该共振过程的最终状态是 2p53dn+1，与 L 边缘实验的最终状态相同。 1s2p RIXS使用硬X射线，不需要超高真空，因此可以用于在原位条件下获得类L边光谱。我们的新贡献是使用 DOC 分析对能量转移 (h - h2) 方向的 RIXS 谱进行定量分析。 2p 孔的长寿命导致了清晰且特征丰富的光谱，可以使用包括构型相互作用的参数化多重态模型精确拟合。随后从理论模型中提取包括 DOC 在内的电子结构。该方法将用于研究激活惰性C?H键的高价酶中间体；血红素化合物 I 和 II、SyrB2 中的非血红素亚铁基氧化中间体和双核铁酶甲烷单加氧酶中的中间体 Q。 RIXS 提供了一种新工具来研究 C?H 键激活的要求，同时也解释了血红素酶和非血红素酶之间的反应性差异。