Structure Function & Biosynthesis of Respiratory Enzymes

结构 功能

• 批准号: 8618284
• 负责人: VICTOR L DAVIDSON
• 金额: $ 36.5万
• 依托单位: UNIVERSITY OF CENTRAL FLORIDA
• 依托单位国家: 美国
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8618284
• 关键词: Aging; Amino Acids; Anabolism; Binding; Biochemical; Biogenesis; Biological; Biological Products; Catalytic Domain; Cells; Cellular Structures; Development; Disease; Electron Transport; Electrons; Enzymes; Free Radicals; Health; Heme; Hydroquinones; Instruction; Kinetics; Metabolism; Modification; Molecular; Mono-S; Oxidative Stress; Oxygen; Post-Translational Protein Processing; Process; Production; Protein Precursors; Proteins; Reaction; Reactive Oxygen Species; Respiration; Site-Directed Mutagenesis; Structure; Structure-Activity Relationship; Tryptophan; cofactor; crosslink; cytochrome c; insight; methylamine dehydrogenase; novel; oxidation; oxidative damage; protein complex; protein protein interaction; protein structure function; respiratory enzyme

This proposal describes how specific enzymes control the transfer of electrons and activation of molecular oxygen, while minimizing oxidative damage. This is central to cell development, health and survival. This project includes studies of enzyme reaction mechanisms, protein structure-function relationships, protein- protein interactions, protein post-translational modification, and mechanisms of long range biological electron transfer. Kinetic, biochemical, spectroscopic and structural studies together with site-directed mutagenesis will be used in these studies. This proposal focuses on the mechanism of biosynthesis ofthe protein-derived cofactor, tryptophan tryptophylquinone (TTQ), and the structure and function of a novel di-heme enzyme MauG which catalyzes the oxygenation and cross-linking of specific tryptophan residues during TTQ biogenesis in methylamine dehydrogenase (MADH). The substrate for MauG is a 119-kDa precursor protein of MADH with mono-hydroxylated Trp57 and no cross-link. MauG catalyzes the 6-electron oxidation ofthe substrate that results in the second oxygenation of Trp57, cross-linking of Trp57 and Trp108, and oxidation ofthe quinol product ofthe first two reactions to form oxidized TTQ. These studies will describe a new biological mechanism for oxygen activation and factors that make specific amino acid residues in proteins susceptible to oxidative modification.The results will provide insight for development of strategies to introduce novel catalytic sites into proteins and manipulate the functions of enzyme-bound hemes, as well as provide clues as to how one might mitigate naturally occurring oxidative damage to proteins. Ongoing mechanistic studies of biological electron transfer (ET) in the MADH-amicyanin-cytochrome c-551 i protein complex will be extended and ET studies will be initiated with MauG. Defining mechanisms of long range ET reactions will enhance our understanding ofthe fundamental processes of respiration and intermediary metabolism at the molecular level. A fundamental understanding ofthe mechanisms of control of biological ET reactions will provide insight into how defective protein ET leads to production of reactive oxygen species and free radicals both of which are associated with many disease states, oxidative stress and aging. RELEVANCE (See instructions): Reactive oxygen species and free radicals produced as by-products of biological electron transfer and oxygen metabolism damage cell components that cause many disease states, oxidative stress and aging. However, free radicals and reactive oxygen species are also used productively in biosynthetic processes. These studies describe how specific enzymes control the transfer of electrons and activate oxygen, while m i n i m i z i n g o x i d a t i v e d a m a g e : . '. ^

该提议描述了特定的酶如何控制电子的转移和分子的活化。 氧气，同时最大限度地减少氧化损伤。这是细胞发育、健康和生存的核心。这 项目包括酶反应机制，蛋白质结构-功能关系，蛋白质- 蛋白质相互作用、蛋白质翻译后修饰和远程生物电子机制 转移动力学、生物化学、光谱和结构研究以及定点突变 将用于这些研究。该建议的重点是蛋白质衍生的生物合成的机制 辅助因子，色氨酸醌（TTQ），和一种新的双血红素酶的结构和功能 MauG在TTQ期间催化特定色氨酸残基的氧化和交联 甲胺脱氢酶（MADH）的生物合成。MauG的底物是一种119 kDa的前体蛋白 具有单羟基化Trp 57且无交联的MADH。MauG催化6-电子氧化 导致Trp 57的第二次氧化、Trp 57和Trp 108的交联和氧化的底物 前两个反应的醌醇产物形成氧化的TTQ。这些研究将描述一种新的 氧活化的生物学机制和蛋白质中产生特定氨基酸残基的因素 易受氧化修饰的影响。研究结果将为开发 在蛋白质中引入新的催化位点，操纵酶结合血红素的功能，以及 提供了如何减轻自然发生的蛋白质氧化损伤的线索。正在进行 MADH-amicyanin-cytochrome c-551 i蛋白生物电子传递机制的研究 将扩展复杂性，并将使用MauG启动ET研究。确定远程ET的机制 反应将增强我们对呼吸和中介的基本过程的理解 在分子水平上的代谢。对生物控制机制的基本认识 ET反应将提供深入了解如何有缺陷的蛋白质ET导致生产的活性氧 和自由基，两者都与许多疾病状态、氧化应激和衰老有关。 相关性（参见说明）： 作为生物电子转移的副产物产生的活性氧和自由基， 氧代谢损害导致许多疾病状态、氧化应激和衰老的细胞成分。 然而，自由基和活性氧也被有效地用于生物合成过程。 这些研究描述了特定的酶如何控制电子的转移和激活氧气， m i n i m i z i n g o x i d a t i v e d a m a g e：. '. ^