Structure Function & Biosynthesis of Respiratory Enzymes

这项建议描述了特定的酶如何控制电子的转移和分子的激活。 氧气，同时将氧化损伤降至最低。这对细胞发育、健康和生存至关重要。这 该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长程生物电子机制 调职。结合定点突变的动力学、生化、光谱和结构研究 将在这些研究中使用。这一建议侧重于蛋白质来源的生物合成的机制。 辅因子色氨酸-色氨酸-苯二酚(TTQ)和一种新的双血红素酶的结构和功能 在TTQ过程中催化特定色氨酸残基氧化和交联的MAUG 甲胺脱氢酶(MADH)的生物发生MAUG的底物是119 kDa的前体蛋白。 单羟基Trp57，无交联物的MADH。MAUG催化6电子氧化 导致Trp57的二次氧化、Trp57和Trp108的交联以及氧化的底物 前两个反应生成的苯二酚产物生成氧化的TTQ。这些研究将描述一种新的 氧激活的生物学机制和蛋白质中特定氨基酸残基的形成因素 易受氧化修饰。研究结果将为制定战略提供洞察力 将新的催化位点引入蛋白质，操纵酶结合的血红素的功能，以及 提供关于如何减轻对蛋白质的自然氧化损伤的线索。正在进行中 MADH-氨基花青素-细胞色素c-551I蛋白生物电子传递机制的研究 综合体将被延长，ET研究将与MAUG一起启动。定义远程ET的机制 反应将加强我们对呼吸和中介的基本过程的理解 分子水平的新陈代谢。对生物防治机制的基本认识 ET反应将深入了解有缺陷的蛋白质ET如何导致活性氧物种的产生 和自由基，这两者都与许多疾病状态、氧化应激和衰老有关。 相关性(请参阅说明)： 作为生物电子转移的副产物产生的活性氧物种和自由基 氧代谢破坏细胞成分，导致许多疾病、氧化应激和衰老。 然而，在生物合成过程中，自由基和活性氧物种也被大量使用。 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，而 我是我是ZI和GO，我是说这是最好的办法。‘。^

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 : . '. ^