XES AND XAS STUDIES OF SOLUBLE METHANE MONOOXYGENASE

可溶性甲烷单加氧酶的 XES 和 XAS 研究

• 批准号: 8170364
• 负责人: SERENA D DE BEER GEORGE
• 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/8170364
• 关键词: Active Sites; Bacteria; Binding; Biological Process; Complement; Complex; Computer Retrieval of Information on Scientific Projects Database; Data; Diamond; Dioxygen; Funding; Grant; Hydroxylation; Institution; Measures; Methane; Methane hydroxylase; Methods; Modeling; Nature; Oxygen; Research; Research Personnel; Resources; Source; Structure; Theoretical Studies; United States National Institutes of Health; computer studies; electronic structure; emission spectroscopy; insight

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. Biologically, the hydroxylation of methane is carried out by methane monoxygenases(MMO) found in methantrophic bacteria. The soluble form of MMO utilizes a diiron active site, which reacts with dioxygen to generate a -peroxo-Fe(III)Fe(III) species (MMO-P) and then an Fe(IV)Fe(IV) species (MMO-Q), which is responsible for oxidizing methane. The intermediates of the MMO catalytic cycle have been the subject of intense experimental and theoretical studies. However, MMO-Q and MMO-P have eluded structural characterization, and many questions about the nature of these intermediates remain. The experimental data for MMO-P have been used to argue for a cis-mu-1,2-peroxo bridging mode, while computational studies favor a mu-2:2-O2 core. For MMO-Q the 2.5 ¿ Fe-Fe distance from EXAFS favors a bis-mu-oxo Fe(IV)-Fe(IV) diamond core structure. However, no vibrational data exist to support any of the postulated core structures and the mechanism for conversion of MMO-P to MMO-Q is unknown. The proposed research is aimed at elucidating the electronic structure of these key intermediates in methane hydroxylation by utilizing new spectroscopic methods. K-Beta x-ray emission spectroscopy is proposed as a selective probe of the Fe2O2 upper valence region, which should provide a sensitive measure of the oxygen bond strength and the binding mode. These data will be complemented by conventional XAS data and correlated to DFT calculations of the spectra. Our initial studies will focus on well characterized model complexes and will then be extended to the enzymatic intermediates. The results of these studies should provide fundamental insights into the biological process of methane hydroxylation.

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。 在生物学上，甲烷的羟基化是由甲烷营养细菌中发现的甲烷单加氧酶（MMO）进行的。MMO的可溶形式利用二铁活性位点，其与分子氧反应以生成α-过氧-Fe（III）Fe（III）物质（MMO-P），然后生成Fe（IV）Fe（IV）物质（MMO-Q），其负责氧化甲烷。MMO催化循环的中间体一直是实验和理论研究的主题。然而，MMO-Q和MMO-P的结构表征，以及这些中间体的性质的许多问题仍然存在。MMO-P的实验数据已被用于论证顺式-mu-1，2-过氧桥接模式，而计算研究有利于mu-2：2-O2核心。对于MMO-Q，EXAFS的2.5 <$Fe-Fe距离有利于双-mu-氧代Fe（IV）-Fe（IV）金刚石核结构。然而，不存在振动数据来支持任何假定的核心结构，并且MMO-P转化为MMO-Q的机制是未知的。本研究的目的是利用新的光谱方法来阐明甲烷羟基化反应中这些关键中间体的电子结构。K-β X射线发射光谱提出作为一个选择性的探头的Fe 2 O2的上价区域，这应该提供一个灵敏的测量的氧键强度和结合模式。这些数据将补充传统的XAS数据和相关的DFT计算的光谱。我们的初步研究将集中在良好的特点模型复合物，然后将扩展到酶的中间体。这些研究的结果应该提供基本的见解甲烷羟基化的生物过程。