Polynuclear iron complexes as functional mimics of the nitrogenase FeMo-cofactor

多核铁配合物作为固氮酶 FeMo 辅因子的功能模拟物

基本信息

批准号：
9982407
负责人：
Theodore A Betley
金额：
$ 31.45万
依托单位：
HARVARD UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-15 至 2022-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9982407
关键词：
Active Sites Address Alkanes Behavior Binding Biological Biological Process Chemical Actions Chemistry Cluster Analysis Coenzymes Complex Coupling Cysteine Dependence Development Electrons Enzymes Face Fluorescence Funding Goals Homo Individual Ions Iron Laboratories Life Ligands Light Measures Mediating Metal Binding Site Metals Methane Methodology Mind Modeling Molecular Molybdenum Molybdoferredoxin Mononuclear Multinuclear NMR Mutagenesis Nature Nitrogen Nitrogen Fixation Nitrogenase Nylons Oxidation-Reduction Pair Bond Pathway interactions Process Reaction Research Roentgen Rays Role Series Site Structural Models Structure Study models Sulfides Surface Surveys System Techniques Testing Theoretical model Variant X ray diffraction analysis absorption adduct analog base cofactor diazene electronic structure flexibility functional mimics interstitial metalloenzyme oxidation sample fixation small molecule uptake

项目摘要

Project Summary: Functional models of the polynuclear nitrogen-fixing enzyme cofactors Nitrogen entry into the biosphere is the rate-limiting step for all biological processes, and therefore, life itself. Dinitrogen reduction occurs at polynuclear metalloenzymes called nitrogenase. The reaction center of the Molybdenum-containing enzyme consists of a cysteine ligated MoFe7S7 cofactor (FeMoco) where dinitrogen fixation takes place. Despite good structural information about the cofactor, many questions regarding substrate uptake and the overall chemical action of the cofactor during turnover remain. Specifically, the redox flexibility of Mo point to its likely involvement in substrate activation, which has been vetted by functional model studies. However, site-mutagenesis studies and theoretical models indicate a polynuclear Fe-face of FeMoco to participate in substrate activation. Synthetic structural analogues have been fashioned to reproduce the cofactor composition and elucidate structural details that mimic the cofactor. However, no synthetic models exist that would permit probing of the interaction between nitrogenase substrates and a polynuclear reaction site reminiscent of those present in FeMo/FeV/Feco. Using synthetic methodology developed in our laboratories to reliably synthesize polynuclear clusters, the goal of the proposed research is to both functionally and structurally model the active site of FeMoco. Polyamide and polyamide/sulfide ligand systems permit the isolation and study of well-defined tri- and hexanuclear iron complexes. The molecular tri-iron units will allow systematic examination of the reaction chemistry of nitrogenase substrates with an iron-only reaction site. Furthermore, bimolecular coupling of tri-iron units will permit the synthesis and characterization of various structural mimics of the cofactor featuring different interstitial atom components (e.g., C, N, O, S). The proposed research will permit the testing of several hypotheses concerning interaction of nitrogenase substrates with polynuclear reaction sites prevalent in the native enzyme: how do substrates bind; how is redox distributed throughout the cluster reaction site; how do surface hydrides gate dinitrogen or substrate binding; can we authenticate mechanistic proposal for the enzyme by observation of abiological models? The viability of the synthetic analogues to mimic nitrogenase activity will be probed by profiling the reactivity of the synthetic clusters towards nitrogenase substrates.

项目摘要：多核氮固定酶辅因子的功能模型氮进入生物圈是所有生物过程的限制步骤，因此是生命本身。减少二氮的发生在称为氮酶的多核金属酶。反应中心含钼的酶由半胱氨酸连接的mofe7s7辅因子（femoco）组成，其中dinitrogen 固定发生。尽管有关辅助因子的良好结构信息，但有关基材的许多问题在周转期间，辅助因子的吸收和整体化学作用仍然存在。具体而言，氧化还原的灵活性 MO指出了它可能参与底物激活，该激活已通过功能模型研究审查。然而，现场 - 毒素研究和理论模型表明Femoco的多核Fe面参与底物激活。合成结构类似物已被造成复制辅助因子组成和阐明模仿辅助因子的结构细节。但是，尚无合成模型将允许探测氮酶底物与多核反应位点之间的相互作用让人联想到Femo/FEV/FECO中存在的人。使用在我们的实验室中开发的合成方法论可靠地合成多核簇，该研究的目的是在功能和结构上均可建模Femoco的主动部位。聚酰胺和聚酰胺/硫化物配体系统允许分离和研究定义明确的三 - 六核铁络合物。分子三铁单元将允许系统检查氮酶底物与仅铁反应位点的反应化学。此外，双分子三铁单元的耦合将允许综合和表征辅因子的各种结构模仿具有不同的间质原子成分（例如C，N，O，S）。拟议的研究将允许测试关于氮酶底物与多核反应位点相互作用的几种假设在天然酶中：底物如何结合；氧化还原如何在整个簇反应部位分布；如何进行表面氢化物栅极二氮或底物结合；我们可以对机械提案进行身份验证酶通过观察物种模型？合成类似物对模拟氮酶的生存能力通过分析合成簇对氮酶底物的反应性来探测活性。