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

• 批准号: 9383904
• 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
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9383904
• 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; Formaldehyde; 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; Study models; Sulfides; Surface; Surveys; System; Techniques; Testing; Theoretical model; Variant; X ray diffraction analysis; X-Ray Diffraction; absorption; adduct; analog; base; cofactor; diazene; electronic structure; flexibility; functional mimics; interstitial; metalloenzyme; oxidation; sample fixation; small molecule; uptake

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：多核固氮酶辅因子的功能模型 氮进入生物圈是所有生物过程的限速步骤，因此也是生命本身的限速步骤。 二氮还原发生在称为固氮酶的多核金属酶上。反应中心为 含钼酶由半胱氨酸连接的 MoFe7S7 辅因子 (FeMoco) 组成，其中二氮 发生固定。尽管有关辅因子的结构信息良好，但有关底物的许多问题 周转过程中辅助因子的吸收和整体化学作用仍然存在。具体来说，氧化还原灵活性 Mo 指出它可能参与底物激活，这已经通过功能模型研究进行了审查。 然而，位点诱变研究和理论模型表明 FeMoco 的多核 Fe 面可以 参与底物活化。合成的结构类似物已被用来复制辅因子 组成并阐明模仿辅因子的结构细节。然而，不存在综合模型 将允许探测固氮酶底物和多核反应位点之间的相互作用 让人想起 FeMo/FeV/Feco 中的那些。使用我们实验室开发的合成方法 可靠地合成多核簇，拟议研究的目标是在功能和结构上 对 FeMoco 的活性位点进行建模。聚酰胺和聚酰胺/硫化物配体系统允许分离和研究 明确的三核和六核铁络合物。分子三铁单元将允许系统检查 具有仅铁反应位点的固氮酶底物的反应化学。此外，双分子 三铁单元的偶联将允许辅因子的各种结构模拟物的合成和表征 具有不同的间隙原子成分（例如，C、N、O、S）。拟议的研究将允许进行测试 关于固氮酶底物与普遍的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；氧化还原如何分布在整个簇反应位点；如何 进行表面氢化物门二氮或底物结合；我们可以验证机械提案吗 通过观察非生物模型来酶？合成类似物模拟固氮酶的可行性 通过分析合成簇对固氮酶底物的反应性来探测活性。