Materials Approaches for Understanding Biological Energy Transduction and Bifurcation

理解生物能量转换和分叉的材料方法

• 批准号: 9611832
• 负责人: Michael Pegis
• 金额: $ 5.83万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-10 至 2021-09-09
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9611832
• 关键词: Active Sites; Ammonia; Attenuated; Binding; Biological; Biology; Carbon; Catalysis; Chemistry; Complex; Coupled; Coupling; Cytochrome P450; Dioxygen; Disease; Down Syndrome; Electrodes; Electron Transport; Electrons; Environment; Enzymes; Fast Electron; Free Radicals; Goals; Human; Hydrogen Peroxide; In Situ; Investigation; Iron; Kinetics; Lead; Length; Life; Link; Malignant Neoplasms; Metalloporphyrins; Metals; Methods; Mitochondria; Mixed Function Oxygenases; Modeling; Molecular; Multiple Sclerosis; Nitrogenase; Oxidases; Oxidation-Reduction; Phenazines; Play; Porphyrins; Prevention; Proteins; Protons; Reaction; Reactive Oxygen Species; Role; Series; Side; Site; Solid; Source; Spectrum Analysis; Surface; System; Water; biological systems; cofactor; cytochrome c oxidase; disorder prevention; driving force; electron donor; insight; interfacial; metal oxide; metalloenzyme; small molecule

PROJECT SUMMARY/ABSTRACT Metalloenzymes orchestrate complex multiproton/multielectron reactions critical to human life, such as the 6H+/6e- reduction of dinitrogen to ammonia by nitrogenase and the 4H+/4e- reduction of dioxygen to water by monooxygenase enzymes. To accomplish these reactions with minimal loss of partially reduced species (PRS), many metalloenzymes have redox-active cofactors located in close proximity to the active site. These cofactors are often loaded with several electron and proton equivalents prior to substrate binding, enabling selective conversion of the substrate to product with minimal PRS loss. Often, PRSs are highly reactive and lead to cellular damage. For enzymes such as Cytochrome P450 (CYP) and Cytochrome c Oxidase (CcO), loss of PRSs, such as H2O2, is linked to various diseases such as down syndrome, multiple sclerosis and cancer. Therefore, understanding the influence that local electron reservoirs have on the selectivity of multiproton/multielectron transformations may aid the treatment of the aforementioned diseases. In order to fundamentally understand the influence that local electron reservoirs have on the selectivity of multielectron/multiproton transformations, we propose to study the activity and selectivity for O2 reduction using iron porphyrins covalently attached to conductive electrodes as artificial models of O2 reducing enzymes. Rather than using a molecular electron reservoir, we will covalently attach metalloporphyrins to carbon and metal oxide electrode surfaces. We hypothesize that metalloenzymes utilize these redox-loaded cofactors to provide the active site with a highly coupled source of electrons, and that changes to the electron coupling between the donor (electrode) and acceptor (metalloporphyrin) will influence the kinetics of the bifurcating steps leading to the desired product (H2O) or the undesired PRS (H2O2). By using an electrode as a tunable surrogate for a redox cofactor, these interfacial constructs will allow a multidimensional control of the distance, coupling and electron transfer driving force between the electrode and iron porphyrin active site, enabling a fundamental study of the steps that lead to bifurcation and loss of PRS in enzymes such as CcO and CYP. These studies will provide insights into how redox-active cofactors influence product bifurcation in metalloenzymes, which may lead to new methods of treatment or prevention of diseases induced by H2O2 loss in biological systems.

项目概要/摘要 金属酶协调对人类生命至关重要的复杂多质子/多电子反应，例如 固氮酶将二氮还原为氨的 6H+/6e- 以及氮酶将二氧还原为水的 4H+/4e- 单加氧酶。为了在部分还原物质 (PRS) 损失最小的情况下完成这些反应， 许多金属酶具有位于活性位点附近的氧化还原活性辅因子。这些辅助因子 通常在底物结合之前加载多个电子和质子当量，从而实现选择性 以最小的 PRS 损失将底物转化为产物。通常，PRS 具有高度反应性并导致细胞 损害。对于细胞色素 P450 (CYP) 和细胞色素 c 氧化酶 (CcO) 等酶，PRS 丢失，例如 H2O2 与多种疾病有关，如唐氏综合症、多发性硬化症和癌症。所以， 了解局部电子库对多质子/多电子选择性的影响 转化可能有助于治疗上述疾病。 为了从根本上理解局域电子库对选择性的影响 多电子/多质子转化，我们建议研究 O2 还原的活性和选择性 使用共价连接到导电电极的铁卟啉作为 O2 还原酶的人工模型。 我们不使用分子电子库，而是将金属卟啉共价连接到碳和金属上 氧化物电极表面。我们假设金属酶利用这些氧化还原负载的辅因子来提供 具有高度耦合的电子源的活性位点，并且这改变了 供体（电极）和受体（金属卟啉）将影响分叉步骤的动力学，导致 所需产物 (H2O) 或不需要的 PRS (H2O2)。通过使用电极作为可调替代品 氧化还原辅因子，这些界面结构将允许对距离、耦合和 电极和铁卟啉活性位点之间的电子转移驱动力，使基础研究成为可能 导致 CcO 和 CYP 等酶中 PRS 分叉和丢失的步骤。这些研究将 提供有关氧化还原活性辅因子如何影响金属酶中产物分叉的见解，这可能导致 治疗或预防生物系统中 H2O2 损失引起的疾病的新方法。