Reactivity-Activation of O(2) or NO in Copper and Heme-Cu Coordination Complexes

项目摘要 拟议的调查来自两个正在进行的R 01转基因研究计划。研究目的 包括合成模型的设计，合成和研究，这将有助于阐明 与铜和血红素相关的结构、M-连接、光谱学和反应性的基本方面/M （M = Cu，Fe）处理分子氧（O2（g））和一氧化氮（NO（g））。关注的铜蛋白 包括溶解性多糖单加氧酶（LPMO）、颗粒甲烷单加氧酶 （pMMO），包括多巴胺β-单加氧酶（DBM）和肽基甘氨酸的酶家族 单加氧酶（PHM）和偶联的双核铜蛋白NspF。最近的生物化学研究 提出了关于其活性部位的性质和涉及的作用机制的问题 O2（g）活化和C-H羟基化。LPMO可能是过氧合酶（H2 O2共底物），新的pMMO 研究表明一个单铜活性位点，现在质疑DBM和PHM是否激活 O2与Cu对Cu 2中心过程。与这些问题相关的是， 并表征了迄今为止难以捉摸的铜（II）-氧（CuII-O·）物种;它具有所需的氧化能力 对于困难的LPMO或pMMO基板。我们还计划阐明对OO至关重要的基本原理 在所有单加氧酶（和氧化酶）中发生的还原裂解过程。此外，我们将生成和 表征了新型高价双核Cu（II）-O-Cu（III）的结构、物理性质和反应活性 或相关的复合物。否则，建议的研究将集中在血红素铜活性位点存在 在细胞色素c氧化酶中，其中O2-结合并被还原裂解以产生两摩尔当量的水。的 合成模型的研究可以帮助阐明细节，并有助于理解结构，O2-结合， 质子或氢键促进O-O断裂，活性位点苯酚（在His-Tyr 辅因子）作为质子-电子供体。建议进行调查，以进一步调查的机制 在血红素-过氧-铜结构中的O-O断裂，其中卟啉，Fe轴向配体和 特别是铜离子的配体，是系统地变化的。计划采取各种办法， 包括研究具有三个N-供体和附加的苯酚的铜的新螯合物。NO（g） 还将开展铜和血红素-M的合成模拟化学次级项目。与铜 复合物，重点将是NO（g）还原偶联，和有关机制的调查 NO（g）与金属离子结合，形成N-N键，得到推定的次硝酸根N2 O22- 中间体，以及质子和/或氢键对N-O裂解和N2 O形成的贡献。 血红素/Fe（或Cu）介导的NO（g）还原偶联在NO还原酶和化学中是关键的， 将研究该过程的合成模型。金属过氧亚硝酸盐（PN，来自金属离子+ O2（g）+ NO（g））反应性，特别是对CO2，也将研究相关的生物活性。

Project Summary Proposed investigations derive from two on-going R01 GM research programs. The study objectives include the design, synthesis & investigation of synthetic models which will aid the elucidation of fundamental aspects of structure, M-ligation, spectroscopy and reactivity relevant to copper and heme/M (M = Cu, Fe) processing of molecular oxygen (O2(g)) and nitric oxide (NO(g)). Copper proteins of concern include lytic polysaccharide monooxygenases (LPMOs), particulate methane monooxygenases (pMMOs), the enzyme family which includes dopamine beta-monooxygenase (DBM) and peptidylglycine monooxygenase (PHM), and a coupled binuclear copper protein, NspF. Recent biochemical research has raised questions concerning the nature of their active sites and the mechanism(s) of action involving O2(g) activation and C-H hydroxylation. LPMOs may be peroxygenases (H2O2 co-substrate), new pMMO studies suggest a mono-Cu active site, and it is now questioned as to whether DBM and PHM activate O2 with a Cu versus a Cu2 center process. Relevant to these issues, there are clear needs to synthesize and characterize the thus-far elusive copper(II)-oxyl (CuII-O·) species; it has the oxidizing ability needed for the difficult LPMO or pMMO substrates. We also plan to elucidate fundamentals critical to the O-O reductive cleavage process occurring in all monooxygenases (& oxidases). Also, we will generate and characterize the structures, physical properties and reactivity of new high-valent binuclear Cu(II)-O-Cu(III) or related complexes. Otherwise, proposed research will focus on the heme-copper active site present in cytochrome c oxidases, where O2-binds and is reductively cleaved to give two mole-equiv water. The study of synthetic models can help elucidate details and aid an understanding of structure, O2-binding, proton or H-bonding facilitated O-O cleavage, and the role of the active-site phenol (in the His-Tyr cofactor) as a proton-electron donor. Investigations are proposed to further investigate the mechanisms of O-O cleavage in heme-peroxo-copper constructs, where the porphyrinate, the Fe axial ligand and especially the ligand for copper ion, are systematically varied. A variety of approaches are planned, including study of new chelates for copper which possess three N-donors and an appended phenol. NO(g) synthetic model chemistry sub-projects with copper and heme-M will also be carried out. With copper complexes, the focus will be on NO(g) reductive coupling, and investigation of mechanisms pertaining to the NO(g) binding to metal ion(s), formation of the N–N bond giving putative hyponitrite N2O22– intermediates, and proton and/or H-bonding contributions to N–O cleavage and formation of N2O. Heme/Fe (or Cu) mediated NO(g) reductive coupling is critical in NO-Reductases and chemistry and synthetic models for this process will be investigated. Metal-peroxynitrite (PN, from metal ion + O2(g) + NO(g)) reactivity, especially toward CO2, will also be studied in relation to the relevant biological activity.