Proton-Coupled Electron Transfer with Biomimetic Models of the [2Fe-2S] Rieske Cl

质子耦合电子转移与 [2Fe-2S] Rieske Cl 仿生模型

• 批准号: 8326445
• 负责人: Caroline Thalia Saouma
• 金额: $ 4.92万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-16 至 2014-08-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8326445
• 关键词: 2,4-thiazolidinedione; ATP Synthesis Pathway; Active Sites; Affect; Attention; Biochemical Process; Biological; Biological Models; Biological Process; Biomimetics; Carbon Dioxide; Carbon monoxide dehydrogenase; Chemicals; Complex; Coupled; Coupling; Crystallography; Disease; Drug Delivery Systems; Electron Transport; Electronics; Electrons; Enzymes; Excision; Family; Foundations; Future; Glutathione; Goals; Histidine; Hydrogenase; Imidazole; Iron; Kinetics; Knowledge; Lead; Life; Ligands; Magnetism; Magnetometries; Measurement; Measures; Mediating; Mediator of activation protein; Membrane; Metals; Mitochondria; Mitochondrial Myopathies; Modeling; Molybdoferredoxin; Nature; Nitrogenase; Non-Insulin-Dependent Diabetes Mellitus; Oxidation-Reduction; Oxidative Stress; Pharmaceutical Preparations; Play; Process; Property; Proteins; Protons; Quinones; Reaction; Reactive Oxygen Species; Regulation; Research; Role; Side; Site; Source; Spectrum Analysis; Stroke; Study models; Sulfur; System; Techniques; Therapeutic; Thiazolidinediones; Tissues; Wolfram Syndrome; Work; analog; biological systems; cofactor; design; electronic structure; enzyme mechanism; insight; interest; metalloenzyme; oxidation; protonation; research study; semiquinone; trend

DESCRIPTION (provided by applicant): Iron sulfur clusters are viewed as the prototypical electron transfer cofactors, but there is increasing evidence in a number of systems that such clusters undergo proton-coupled electron transfer (PCET). In the mitochondria, for instance, several [2Fe-2S] clusters mediate PCET reactions, including Rieske clusters, which are involved with ATP synthesis, and mitoNEET clusters, which help regulate this process. Both of these clusters facilitate PCET, and proposed here are model studies to develop a detailed understanding of such processes. As part of the Q-cycle of the bc1 complex, Rieske clusters are involved in the redox cycling of quinones, a process that requires tight regulation to avoid formation of semiquinone intermediates which ultimately leads to oxidative stress and tissue damage. The mitoNEET protein has been identified as the target of the thiazolidinedione (TZD) family of drugs, which are used to treat type 2 diabetes, and this protein is a SRWHQWLDO WDUJHW IRU $O]KHLPHU6V 3DUNLQVRQ6V DQG VWURNH GUXJV Knowledge of how these and related clusters mediate PCET is key to understanding their biological function and could lay the foundation for new treatments. Owing to the complexity of the biological systems, this understanding is best developed with well- characterized model systems. The goals of the proposed experimental studies are: i) to prepare and study the PCET reactivity of synthetic [2Fe-2S] clusters that are models for Rieske and mitoNEET clusters, and ii) to establish factors that affect the rate and mechanism of PCET to/from [Fe-S] clusters. Biomimetic [2Fe-2S] clusters will be prepared in both biologically relevant oxidation states, FeIII/III and FeII/III, and in both their protonated and deprotonated states. These congeners will be thoroughly characterized by a variety of techniques, including NMR, IR, EPR, and UV-vis spectroscopy, SQUID magnetometry, and x-ray crystallography. The thermochemical properties of these clusters - their redox potentials and pKa values 1 will also be measured. Kinetic and mechanistic studies of PCET and ET reactions will then be undertaken, with an emphasis on biologically relevant reactions. Combining all these various measurements will lead to a detailed description of the PCET reactivity of such clusters, including, for example, how the extent of magnetic coupling between the two iron centers affects PCET. These systems will then be compared with other model [Fe-S] systems that do not contain an imidazole or imidazolate ligand. Protonation of these congeners will likely occur at the sulfur, providing an understanding of how the site of protonation affects PCET at [Fe-S] clusters. Collectively, these studies will provide a fundamental description of PCET at [Fe-S] clusters, and the results of these studies may provide insights to the above-mentioned diseases. Additionally, these results will guide future mechanistic proposals for enzymes that feature [Fe-S] clusters, and will further our understanding of PCET at sulfur and at multi-metallic sites, both of which are prevalent in biological systems.

描述（由申请人提供）：铁硫簇被视为原型电子转移辅因子，但在许多系统中有越来越多的证据表明，这种簇进行质子耦合电子转移（PCET）。例如，在线粒体中，几个[2Fe-2S]簇介导PCET反应，包括参与ATP合成的Rieske簇和帮助调节该过程的mitoNEET簇。这两个集群促进PCET，并提出了在这里的模型研究，以发展这样的过程的详细了解。作为bc 1复合物的Q-循环的一部分，Rieske簇参与醌的氧化还原循环，这是一个需要严格调节以避免形成半醌中间体的过程，最终导致氧化应激和组织损伤。mitoNEET蛋白已被鉴定为噻唑烷二酮（TZD）家族药物的靶点，TZD家族药物用于治疗2型糖尿病，该蛋白质是一种[SRWHQWLDO WDUJHW IRU $O] KHLPHU 6V 3DUNLQVRQ 6V DQG VWURNH GUXJV]了解这些和相关簇如何介导PCET是理解其生物学功能的关键，可以为新的治疗方法奠定基础。由于生物系统的复杂性，这种理解是最好的发展与良好的特征化模型系统。 所提出的实验研究的目标是：i）制备和研究合成的[2Fe-2S]簇的PCET反应性，所述簇是Rieske和mitoNEET簇的模型，以及ii）建立影响PCET到[Fe-S]簇/从[Fe-S]簇的速率和机制的因素。仿生[2Fe-2S]簇将在生物相关的氧化态，Fe III/III和Fe II/III，并在其质子化和去质子化状态。这些同源物将通过各种技术，包括核磁共振、红外、电子顺磁共振和紫外-可见光谱、超导量子干涉仪磁力测量和X射线晶体学进行彻底的表征。还将测量这些簇的热化学性质-它们的氧化还原电位和pKa值1。然后将进行PCET和ET反应的动力学和机理研究，重点是生物相关反应。结合所有这些不同的测量将导致这样的集群的PCET反应的详细描述，包括，例如，两个铁中心之间的磁耦合的程度如何影响PCET。然后将这些系统与不含咪唑或咪唑酯配体的其他模型[Fe-S]系统进行比较。质子化的这些同源物可能会发生在硫，质子化的网站如何影响PCET在[Fe-S]集群的理解。总的来说，这些研究将提供一个基本的描述PCET在[Fe-S]集群，这些研究的结果可能会提供上述疾病的见解。此外，这些结果将指导未来的机制建议的酶功能[Fe-S]集群，并将进一步我们的理解PCET在硫和多金属网站，这两者都是普遍存在于生物系统。