STRUCTURE-FUNCTION & BIOSYNTHESIS OF RESPIRATORY ENZYMES

结构-功能

• 批准号: 2180920
• 负责人: VICTOR L DAVIDSON
• 金额: $ 19.66万
• 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/2180920
• 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.

该提案的目标是 (i) 定义以下机制： 选定的醌蛋白脱氢酶的催化和电子转移 及其醌辅基，（ii）定义其机制 从这些脱氢酶到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 (iii) 定义稳定特定相互作用的因素 这些可溶性弱缔合蛋白之间促进相互作用 分子电子转移。 这些过程将由稳定的检查 状态和快速动力学、直接结合测定、热力学分析 以及合作生物物理和 X 射线晶体学研究。 奎宁蛋白是一类细菌和真核酶， 拥有新的醌作为辅基并催化 生物相关胺、醇、糖和的氧化 醛类。 奎宁蛋白脱氢酶与大多数其他酶不同 氧化还原酶，因为它们的直接电子受体不是氧 或可溶性辅因子，例如 NAD+，但具有电子转移性 蛋白质，例如细胞色素和铜蛋白。 醌辅因子， 例如吡咯并喹啉醌 [PQQ]，已被证明是必需的 哺乳动物的营养物质，并被认为可能具有治疗作用 用于治疗多种与氧化应激相关的疾病的药物。 像这样， 了解此类醌在催化和电子中的作用 转移将具有广泛意义。 拟议的研究将 描述酶结合醌在氧化中的作用 通过选择的醌蛋白脱氢酶分解胺和醇。 这将 具有普遍意义，因为我们之前已经表明该机制 甲胺脱氢酶氧化胺的用途与 哺乳动物胺氧化奎宁蛋白、血浆胺所使用的 氧化酶和赖氨酰氧化酶。 影响因素的阐明 奎宁蛋白及其蛋白质之间的特定蛋白质-蛋白质相互作用 电子受体蛋白，促进分子间电子 转移，将进一步我们对蛋白质过程的理解 蛋白质识别是多种生物所共有的 现象。 长程机制和途径的表征 分子间电子转移将使我们更好地理解 分子水平上呼吸的基本过程。