STRUCTURE-FUNCTION & BIOSYNTHESIS OF RESPIRATORY ENZYMES

结构-功能

• 批准号: 3299786
• 负责人: VICTOR L DAVIDSON
• 金额: $ 19.32万
• 依托单位: UNIVERSITY OF MISSISSIPPI MED CTR
• 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 1997-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3299786
• 关键词: X ray crystallography; biophysics; cellular respiration; chemical binding; chemical kinetics; cofactor; cytochromes; electron transport; enzyme biosynthesis; enzyme inhibitors; enzyme mechanism; enzyme structure; enzyme substrate; high performance liquid chromatography; oxidoreductase; protein purification; protein sequence; quinones; respiratory enzyme; semiquinone; site directed mutagenesis; thermodynamics

The objectives of this proposal are (i) to define the mechanisms of catalysis and electron transfer by selected quinoprotein dehydrogenases and their quinone prosthetic groups, (ii) to define the mechanisms of long range electron transfer from these dehydrogenases to soluble redox proteins which subsequently transfer electrons to the respiratory chain and (iii) to define the factors which stabilize the specific interactions between these soluble weakly-associating proteins that facilitate inter- molecular electron transfer. These processes will be examined by steady- state and rapid kinetics, direct binding assays, thermodynamic analysis and collaborative biophysical and x-ray crystallographic studies. Quinoproteins are a class of bacterial and eukaryotic enzymes which possess novel quinones as prosthetic groups and which catalyze the oxidation of biologically relevant amines, alcohols, sugars and aldehydes. Quinoprotein dehydrogenases are distinct from most other oxidoreductases in that their immediate electron acceptors are not oxygen or soluble cofactors, such as NAD+, but are electron transferring proteins, such as cytochromes and copper proteins. Quinone cofactors, such as pyrroloquinoline quinone [PQQ], have been shown to be essential nutrients for mammals and have been implicated as possible therapeutic agents for a variety of disorders related to oxidative stress. As such, an understanding of the role of such quinones in catalysis and electron transfer will be of broad significance. The proposed studies will describe the roles of the enzyme-bound quinones in the oxidation of amines and alcohols by selected quinoprotein dehydrogenases. This will be of general interest as we have previously shown that the mechanism used by methylamine dehydrogenases to oxidize amines is very similar to that used by the mammalian amine oxidizing quinoproteins, plasma amine oxidase and lysyl oxidase. Elucidation of the factors which influence the specific protein-protein interactions between quinoproteins and their electron acceptor proteins, and facilitate intermolecular electron transfer, will further our understanding of the process of protein- protein recognition which is common to a wide range of biological phenomena. Characterization of the mechanisms and pathways of long range intermolecular electron transfer will allow us to better understand the fundamental process of respiration at the molecular level.

这项提案的目标是：(一)界定 部分藜麦蛋白脱氢酶的催化作用和电子传递 和它们的苯醌假体基团，(Ii)确定其作用机制 这些脱氢酶向可溶性氧化还原的长程电子转移 随后将电子转移到呼吸链的蛋白质 以及(Iii)确定稳定特定交互作用的因素 在这些可溶的弱结合蛋白之间，促进相互作用 分子电子转移。这些过程将由STRATE- 状态和快速动力学、直接结合分析、热力学分析 以及合作的生物物理和X射线结晶学研究。 藜麦蛋白是一类细菌和真核生物的酶 具有新的苯二酚作为假体基团，它催化 生物相关的胺、醇、糖和 醛。藜麦蛋白脱氢酶与大多数其他酶不同 氧化还原酶，其直接电子受体不是氧 或可溶性辅因子，如NAD+，但正在进行电子转移 蛋白质，如细胞色素和铜蛋白。对苯二酚辅助因子， 如吡咯喹啉醌[PQQ]，已被证明是必需 用于哺乳动物的营养素，并被认为是可能的治疗方法 治疗与氧化应激有关的各种疾病的药物。因此， 对这些对苯二酚在催化和电子中的作用的认识 转移将具有广泛的意义。拟议的研究将 描述酶结合的苯二酚在氧化过程中的作用。 由精选的藜麦蛋白脱氢酶产生的胺和醇。这将是 引起普遍关注，因为我们之前已经表明，该机制 甲胺脱氢酶用来氧化胺的物质与 被哺乳动物使用的胺氧化藜麦蛋白，血浆胺 酶和赖氨酸氧化酶。对影响因素的解释 藜麦蛋白与其相互作用的研究进展 电子受体蛋白，促进分子间电子 转移，将进一步加深我们对蛋白质过程的理解- 蛋白质识别是一种广泛的生物识别 现象。长程辐射机制和途径的表征 分子间的电子转移将使我们更好地理解 在分子水平上呼吸的基本过程。