STRUCTURE-FUNCTION & BIOSYNTHESIS OF RESPIRATORY ENZYMES

本建议的目标是：（一）确定 通过选择的醌蛋白酶的催化和电子转移 和它们的醌辅基，（ii）以定义 从这些酶到可溶性氧化还原酶的长距离电子转移 随后将电子转移到呼吸链的蛋白质 以及（iii）确定稳定特定相互作用的因素 在这些可溶性弱结合蛋白之间， 分子电子转移 这些过程将通过稳定的- 状态和快速动力学，直接结合分析，热力学分析 以及生物物理学和X射线晶体学的合作研究。 奎宁蛋白是一类细菌和真核生物的酶， 具有新的醌作为辅基，并催化 生物学相关的胺、醇、糖的氧化， 醛类。 Quinoproteinase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，如NAD+，但电子转移 蛋白质，如细胞色素和铜蛋白。 醌辅因子， 例如吡咯并喹啉醌[PQQ]，已经显示是必需 作为哺乳动物的营养素， 用于与氧化应激相关的多种病症的药剂。 因此，在本发明中， 了解这种醌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 描述酶结合醌在氧化中的作用， 胺和醇。 这将 引起普遍兴趣，因为我们之前已经证明该机制 用于氧化胺的甲基胺氧化酶与 哺乳动物的胺氧化醌蛋白，血浆胺 氧化酶和赖氨酰氧化酶。 解释影响因素 quinoproteins之间的特异性蛋白质-蛋白质相互作用及其 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- 蛋白质识别是常见的广泛的生物 现象。 远距离化学反应的机制和途径的表征 分子间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。

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.