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.

该提案的目标是（i）定义的机制 通过选定的醌蛋白脱氢酶的催化和电子转移 以及他们的奎因酮假肢，（ii）定义的机制 远程电子从这些脱氢酶转移到可溶性氧化还原 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 在这些可溶性弱缔合蛋白之间，有助于促进 分子电子转移。 这些过程将通过稳定检查 状态和快速动力学，直接结合测定，热力学分析 以及协作生物物理和X射线晶体学研究。 奎诺蛋白是一类细菌和真核酶，这些酶 将新颖的奎因酮作为假肢，并催化 生物学相关胺，醇，糖和氧化 醛。 醌蛋白脱氢酶与大多数其他不同 氧化还原酶是直接电子受体不是氧气 或可溶性辅因子，例如NAD+，但电子转移 蛋白质，例如细胞色素和铜蛋白。 奎因酮辅因子， 例如吡咯喹啉喹酮[PQQ]，已被证明是必不可少的 哺乳动物的营养成分，并已成为可能的治疗 与氧化应激有关的多种疾病的药物。 像这样， 理解这种奎因酮在催化和电子中的作用 转移将具有广泛的意义。 拟议的研究将 描述酶结合的奎因酮在氧化中的作用 胺和醇通过选定的喹蛋白脱氢酶。 这会 正如我们先前所表明的那样，具有普遍兴趣 甲胺脱氢酶用于氧化胺非常相似 哺乳动物胺氧化喹蛋白，血浆胺的使用 氧化酶和赖氨酸氧化酶。 阐明影响因素 喹蛋白及其其特异性蛋白质 - 蛋白质相互作用 电子受体蛋白，并促进分子间电子 转移，将进一步了解蛋白质的过程 蛋白质识别是广泛的生物学 现象。 远程机制和途径的表征 分子间电子转移将使我们能够更好地了解 分子水平的呼吸的基本过程。