Regulation of NADH: ubiquinone oxidoreductase (complex *

NADH：泛醌氧化还原酶（复合体I）是一种能量转导膜结合蛋白复合体，是电子进入线粒体呼吸链的主要入口。哺乳动物的多亚基酶复合体由43个不同的基因编码。哺乳动物酶表现出极其复杂的动力学行为，所有形式的酶都保留了自然的电子转移途径。复杂的动力学行为表明存在两种不同的缓慢平衡形式的酶。活性(A)形式具有还原泛醌的催化能力，而去活性(D)形式不能将电子转移到膜中的泛醌。这两种形式之间的平衡受到许多调节因素（即pH值、二价阳离子、温度、泛醌/亚二甲基醌/泛醇比）的精细控制。这项研究将主要在俄罗斯进行，作为NIH拨款R01 GM61606的延伸。提议的合作工作是通过使用生物化学和分子方法的结合，在分子机制水平上扩展酶的调节特性的研究。研究将在完整的心脏和线粒体等生理相关系统中进行，以及国外合作实验室的动力学和生化方法。的实验室。本文将研究新兴市场转型的两个主要方面。一是阐明红/氧依赖性D到A转变过程中A和D之间缓慢相互转化的分子机制；以及极度依赖温度的A到D转变。自然配体和修饰剂影响的速度和平衡的ND转移的体外鉴定。第二个目的是关注与langendorff灌注大鼠心脏缺血/再灌注实验模型相关的完整线粒体中复合物I A/D转换。这些研究的重点是确定复合体I的A/D转换在响应细胞代谢变化时可能的生理重要性。复合体I的催化活性对细胞生理学很重要，许多疾病（糖尿病、心肌病）都与复合体I的缺陷有关。即将进行的研究将阐明这种重要呼吸复合体酶活性的调节。

DESCRIPTION (provided by applicant) NADH:ubiquinone oxidoreductase (complex I) is an energy-transducing membrane-bound protein complex that serves as a major entry point for electrons to the mitochondrial respiratory chain. The multisubunit enzyme complex is encoded by 43 separate genes in mammals. The mammalian enzyme shows extremely complex kinetic behavior, in all forms that retain natural electron transfer pathways. The complex kinetic behavior suggests that two distinct slowly equilibrating forms of the enzyme exist. The active (A) form is catalytically capable to reduce ubiquinone, whereas, the de-active (D) form is not able to transfer electrons to ubiquinone in the membrane. The equilibrium between these two forms is under a refined control by a number of regulatory factors (i.e., pH, divalent cations, temperature, the ubiquinone/ubisemiquinone/ubiquinol ratio). This research will primarily be done in Russia as an extension of NIH grant R01 GM61606. The proposed collaborative work is to extend studies of the regulatory characteristics of the enzyme at the molecular mechanistic level by using a combination of biochemical and molecular approaches. The studies will be done in physiologically relevant systems such as intact hearts and mitochondria, as well as, the kinetic and biochemical approaches in the foreign Co-P.l.'s laboratory. Two major aspects of the ND transition are to be investigated. One is to elucidate the molecular mechanisms of the slow interconversion between the A and D forms involved in the red/ox-dependent D to A transition; and the extremely temperature-dependent A to D transition. Natural ligands and modifiers which affect the rate and equilibrium of the ND transition in vitro will be identified. The second aim focusses on the complex I A/D transition in intact mitochondria in relation to the experimental model of ischemia/reperfusion in Langendorff-pertused rat hearts. The focus of these studies is to determine the possible physiological importance of the A/D transition of complex I as it responds to alterations in cellular metabolism. The catalytic activity of complex I is important for cellular physiology and a number of diseases (diabetes, cardiomyopathy) have been associated with defects in complex I. The research to be undertaken will shed light on the modulation of enzyme activity of this important respiratory complex.