Structural Studies on Membrane-Associate Cytochrome B5 and P450 NMR

描述(申请人提供)：拟议研究的主要目标是确定16.7 kDa膜相关细胞色素-b5的结构，这是一种在各种细胞类型中发现的电子转移蛋白。它在细胞色素P450的催化活性中起着重要作用，目前临床上使用的药物中有50%以上是由细胞色素P450代谢的。它还作为电子传递组分参与生物组织中的许多氧化反应，包括脂肪和类固醇的合成代谢。这对蛋白质结构测定的实验技术提出了重大挑战。然而，核磁共振波谱技术在膜蛋白结构测定方面还处于快速发展阶段，最近对几种膜蛋白的研究结果令人振奋，表明细胞色素b5的结构测定是可行的。细胞色素b5的结构将通过溶液核磁共振技术在胶束中确定，在脂质双层中通过固体核磁共振技术确定。在游离和与细胞色素-P450络合的情况下获得的结构将为深入了解细胞色素-b5影响细胞色素-P450催化的分子机制提供依据。公共卫生相关性：细胞色素-b5的拟议结构研究结果将为细胞色素-b5影响细胞色素-P450氧化的分子机制提供见解，细胞色素-P450代谢目前50%以上的药物。这些研究还将使我们了解细胞色素b5在睾酮和大量不饱和脂肪的生物合成中的作用，这是维持细胞膜完整性所必需的。

DESCRIPTION (provided by applicant): The main objective of the proposed research is to determine the structure of a 16.7 kDa membrane-associated cytochrome-b5, an electron transfer protein found in a variety of cell types. It plays a major role in the catalytic activity of cytochrome-P450, which metabolizes more than 50% of the drugs in clinical use today. It is also involved as an electron transfer component in a number of oxidative reactions in biological tissues, which includes the anabolic metabolism of fats and steroids. It presents significant challenges for experimental techniques of protein structure determination. However, structure determination of membrane proteins by NMR spectroscopy is in a rapid phase of development; recent results on several membrane proteins are promising and indicate that the structure determination of cytochrome-b5 is feasible. The structure of cytochrome-b5 will be determined in micelles by solution NMR and in lipid bilayers by solid state NMR techniques. Structures obtained in free and in complexation with cytochrome-P450 will provide insights into the molecular mechanism by which cytochrome-b5 influences the catalysis of cytochrome-P450. PUBLIC HEALTH RELEVANCE: The outcome of the proposed structural studies on cytochrome-b5 will provide insights into molecular mechanism by which cytochrome-b5 influences oxidation by cytochrome- P450 that metabolizes more than 50% of current-day drugs. These studies will also enable us to understand the role of cytochrome-b5 in the biosynthesis of testosterone and numerous unsaturated lipids, which are necessary for maintaining the integrity of cellular membranes.