IRON L-EDGE XAS OF HEME, HIGH-VALENT OXYGEN INTERMEDIATES, AND BINUCLEAR MODELS

血红素、高价氧中间体和双核模型的铁 L 边缘 XAS

• 批准号: 8170325
• 负责人: KEITH O HODGSON
• 金额: $ 0.03万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2011-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8170325
• 关键词: Active Sites; Back; Binding; Complex; Computer Retrieval of Information on Scientific Projects Database; Enzymes; Foundations; Funding; Goals; Grant; Heme; Heme Iron; Hemoglobin; Individual; Institution; Iron; Methane hydroxylase; Methodology; Modeling; Nature; Oxygen; Reaction; Research; Research Personnel; Resources; Series; Source; Structure; United States National Institutes of Health; Work; cytochrome c oxidase; electronic structure; enzyme model; insight; multiplet

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. In studies performed during our previous proposals, a new methodology was developed for analyzing and interpreting iron Ledge transition intensity distributions in terms of the total and differential orbital covalency (DOC). It was found that the integrated iron L-edge intensity could be used to obtain the total covalency of the complex. Furthermore, a projection methodology was developed which allows the covalency of the individual symmetry-related sets of orbitals and the DOC to be experimentally determined from the L-edge multiplet intensity distribution. The previous study serves as a foundation for the series of studies proposed here. Building on previous studies of back-bonding in low-spin heme complexes, a series of high-spin heme complexes will be understood in terms of the L-edge multiplet structure. This work, combined with the L-edge of low-spin heme, will be used to help spectroscopally resolve long-standing issues involving the binding of O2 to hemoglobin. These heme studies will then be applied to determining the electronic structure in a series of complexes that serve as models of the enzyme cytochrome c oxidase. The determination of covalency and DOC of these models will provide insight into the electronic structure of this enzyme and differences related to the O-O bond cleavage. Next, because the enzymatic turnover in many non-heme iron enzymes is thought to involve a highvalent Fe(IV)=O intermediate, our understanding of the iron L-edge will be use to look at a series of S=1 and S=2 Fe(IV)=O model complexes known to perform H-atom abstraction. We will then extend these studies to series of high-valent binuclear model complexes with the goal of obtaining mechanistic insight into the active site methane monooxygenase. Finally we will use iron Ledge XAS to understand the nature of the Fe-NO bond as NO in relation to reactions with O2.

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 在我们以前的建议中进行的研究中，开发了一种新的方法来分析和解释铁利奇跃迁强度分布的总和微分轨道共价（DOC）。结果表明，积分铁的L边强度可以用来获得配合物的总共价。此外，开发了一种投影方法，该方法允许从L-边多重峰强度分布实验确定各个与轨道和DOC相关的组的共价性。前面的研究是本文提出的一系列研究的基础。基于先前对低自旋血红素复合物中的背键的研究，一系列高自旋血红素复合物将被理解为L-边多重态结构。这项工作，结合低自旋血红素的L-边缘，将用于帮助光谱解决长期存在的问题，涉及O2与血红蛋白的结合。这些血红素的研究，然后将被应用到确定的电子结构的一系列配合物，作为模型的酶细胞色素c氧化酶。这些模型的共价性和DOC的测定将提供洞察这种酶的电子结构和O-O键断裂相关的差异。接下来，由于许多非血红素铁酶的酶促周转被认为涉及高价Fe（IV）=O中间体，我们对铁L-边的理解将用于研究一系列S=1和S=2 Fe（IV）=O模型络合物，这些络合物已知执行H-原子提取。然后，我们将这些研究扩展到一系列的高价双核模型配合物的目的是获得机械洞察到活性位点甲烷单加氧酶。最后，我们将使用铁凸缘XAS理解的性质的Fe-NO键作为NO与O2的反应。