Understanding protein radicals

了解蛋白质自由基

• 批准号: 8889378
• 负责人: Cecilia Tommos
• 金额: $ 28.88万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-04 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8889378
• 关键词: 3-nitrotyrosine; Address; Aerobic; Amino Acids; Anti-Inflammatory Agents; Anti-inflammatory; Antineoplastic Agents; Aspirin; Biochemical; Biological Models; Biology; Buffers; Chemicals; Chemistry; Complement; Computer Simulation; Coupled; Data Set; Dimerization; Dissociation; Electron Transport; Elements; Environment; Enzymes; Escherichia coli; Family; Foundations; Generations; Glutamates; Goals; Hydrogen; Hydrogen Bonding; Ibuprofen; Induced Mutation; Kinetics; Lasers; Libraries; Life; Measurement; Measures; Methods; Modeling; Modification; Mutation; NMR Spectroscopy; Nature; Organism; Outcome; Oxidation-Reduction; Oxidative Stress; Oxygen; Pathway interactions; Pharmaceutical Preparations; Phenols; Photosensitizing Agents; Positioning Attribute; Process; Production; Property; Protein Chemistry; Protein Dynamics; Proteins; Protons; Reaction; Ribonucleotide Reductase; Role; Ruthenium; Side; Solar Energy; Solutions; Solvents; Sorting - Cell Movement; Spectrum Analysis; Structure; System; Temperature; Thermodynamics; Time; Tyrosine; Variant; Work; base; chemical property; chemical reaction; insight; interest; novel; oxidation; protein E; protein structure; public health relevance; quantum; scaffold; small molecule; tyrosine radical

 DESCRIPTION (provided by applicant): The long-term goal of this proposal is to delineate the mechanisms by which amino-acid radicals participate in both productive and destructive redox reactions in living organisms. Controlled radical chemistry occurs in enzymes that use amino acids in catalytic and multistep electron-transfer reactions. Amino-acid radical enzymes are involved in a range of chemical transformations some of which are fundamental to aerobic life on Earth. It is of vital interest to delineate these chemical reactions in great detail for a numbe of reasons. These include, for example, developing anticancer drugs, understanding the interactions of non-steroidal anti- inflammatory drugs (NSAIDs) such as aspirin and ibuprofen with their protein targets, and laying the foundation for sustainable solar energy production. Importantly, there is also a sinister side to amino-acid radicals as these species are generated during oxidative stress conditions and can cause significant cellular damage. Despite the biochemical importance of amino-acid radicals, surprisingly little is known about their fundamental thermodynamic and kinetic properties. It is very challenging to study these species due to their highly oxidizing and reactive nature. As a result, no guide is currently available for comparing the formal reduction potentials of amino-acid radicals and correlating these values with the properties of the surrounding protein. Studies aimed at characterizing the proton-coupled electron transfer (PCET) reactions associated with tyrosine oxidation-reduction are currently of high interest but are largely conducted on small-molecule models free in solution. The correlation between the solution chemistry and the protein chemistry is not straightforward. Furthermore, it is well known that the protein matrix can modulate the lifetime of the amino- acid radical by many orders of magnitude but there is little information on how this occurs. We have developed a protein system that can provide novel and important information about these issues. The a3X constructs are well-structured proteins supporting reversible amino-acid oxidation-reduction and major radical stabilization. Protein reengineering, solution NMR spectroscopy, (very) high potential protein voltammetry, quantum chemical methods, time-resolved laser spectroscopy, and protein hydrogen exchange (HX) methods will be employed to characterize and refine the redox properties of the a3X proteins. This system will be developed along three connected paths. First, the a3X proteins will be used to generate a unique protein-based "thermodynamic ladder" for interpreting the thermodynamic and kinetic effects of mutations and chemical modifications of amino-acid radicals in natural systems. Second, this project seeks to complement and significantly extend prior solution studies by characterizing tyrosine/phenol-based proton-coupled electron transfer in a structured protein environment. Third, we will investigate how the dynamic properties of the protein ensemble may influence tyrosine radical formation, stabilization and decay.

 描述（由申请人提供）：该提案的长期目标是描述氨基酸自由基参与活生物体中生产性和破坏性氧化还原反应的机制，这些机制在使用氨基酸进行催化的酶中发生。和多步电子转移反应涉及一系列化学转化，其中一些化学转化是地球上有氧生命的基础，描述这些化学反应至关重要。出于多种原因，其中包括开发抗癌药物、了解阿司匹林和布洛芬等非甾体抗炎药 (NSAID) 与其蛋白质靶点的相互作用，以及为可持续太阳能奠定基础。重要的是，氨基酸自由基也有一个险恶的一面，因为这些物质是在氧化应激条件下产生的，尽管氨基酸自由基具有重要的生化作用，但其影响却很小。由于它们的高氧化性和反应性，研究它们的基本热力学和动力学特性非常具有挑战性。 比较氨基酸自由基的形式还原电位，并将这些值与周围蛋白质的特性相关联，旨在表征与酪氨酸氧化还原相关的质子耦合电子转移（PCET）反应的研究目前引起了人们的高度关注。大部分是在溶液中游离的小分子模型上进行的。溶液化学和蛋白质化学之间的相关性并不简单。此外，众所周知，蛋白质基质可以通过多个数量级调节氨基酸自由基的寿命。震级但关于这是如何发生的信息很少。a3X 构建体是支持可逆氨基酸氧化还原和主要自由基稳定性的蛋白质系统。 、溶液核磁共振波谱、（非常）高电位蛋白质伏安法、量子化学方法、时间分辨激光光谱和蛋白质氢交换（HX）方法将用于表征和完善氧化还原性质该系统将沿着三个相互关联的路径进行开发，首先，a3X 蛋白将用于生成基于蛋白质的独特“热力学阶梯”，用于解释氨基酸突变和化学修饰的热力学和动力学效应。其次，该项目旨在通过表征结构化蛋白质环境中基于酪氨酸/酚的质子耦合电子转移来补充和显着扩展先前的解决方案研究。第三，我们将研究蛋白质整体的动态特性。可能影响酪氨酸自由基的形成、稳定和衰变。