Microsomal Cytochromes P450 and their Interactions with their Redox Partners

描述（由申请人提供）：细胞色素P450 （cyt P450）超家族由超过11,000个成员组成。它们无处不在，存在于所有生物和植物的王国中，被称为大自然的喷灯，因为它们能够氧化大量稳定的化学实体。人类拥有56种不同的P450细胞，其中许多对早期发育和生命本身至关重要。其他人类细胞P450决定毒性、作用持续时间和消除绝大多数治疗药物、致癌物和人类暴露的环境因素。外源代谢细胞P450也负责大多数药物-药物相互作用和药物不良反应。第三组细胞P450负责基本内源性化合物的生物合成或代谢。这包括几乎所有的类固醇（胆固醇、胆汁酸、雌激素、睾酮、皮质醇和维生素D）和许多脂质和类二十烷酸。P450细胞几乎存在于人体的每一个器官和组织中。cyts P450不是自给自足的，而是需要与其他蛋白质相互作用才能发挥作用。Cyt P450还原酶和细胞色素b5 （Cyt b5）为Cyt P450提供电子，是支持Cyt P450活性的两种蛋白质。该项目的长期目标是了解膜结合微粒体细胞P450的氧化还原伙伴，cyt P450还原酶和cyt b5调节其活性的结构和机制基础。本提案的短期目标是利用人类和模型cyt P450，了解cyt P450的氧化还原伙伴如何调节其活性、底物特异性和催化机制的生化基础。实验技术，包括定点诱变，通过化学手段快速猝灭细胞P450活性，冷冻，hplc -质谱，量子力学/分子力学计算，将被用来阐明微粒体细胞P450活性是如何被其氧化还原伙伴调节的。了解大自然如何设计cyt P450活性位点是一个基本问题，它对预测和最终改变大量环境污染物（如邻苯二甲酸盐、双酚a、多氯联苯（PCBs））和许多目前使用的药物（包括化疗药物、精神活性化合物和心血管治疗药物）的代谢途径具有重要意义。人类细胞P450活性调控的分子机制知识也将被证明是开发药物和程序的巨大资产，以改变人类细胞P450参与的大量关键生理过程，以及设计毒性更低、特异性更强的治疗药物和前药，特别是化疗药物和环境污染物。

DESCRIPTION (provided by applicant): The cytochrome P450 (cyt P450) superfamily consists of more than 11,000 members. They are ubiquitous, being found in all kingdoms of living organisms and plants and are referred to as Mother Nature's blowtorch, due to their ability to oxidize a vast number of stable chemical entities. Humans possess 56 different cyts P450, many of which are essential for early development and life itself. Other human cyts P450 determine the toxicity, duration of action, and elimination of the vast majority of therapeutic agents, carcinogens, and environmental agents to which humans are exposed. Xenobiotic metabolizing cyts P450 are also responsible for the majority of drug-drug interactions and adverse drug reactions. A third group of cyts P450 are responsible for the biosynthesis or metabolism of essential endogenous compounds. This includes virtually all steroids (cholesterol, bile acids, estrogens, testosterone, cortisol, and vitamin D) and many lipids and eicosanoids. Cyts P450 exists in virtually every organ and tissue of humans. The cyts P450 are not self-sufficient but rather require interactions with other proteins in order to function. Cyt P450 reductase and cytochrome b5 (cyt b5), which provide electrons to cyt P450, are two proteins that support the activity of cyt P450. The long-term goal of this project is to understand the structural and mechanistic basis for the regulation of the activity of the membrane-bound microsomal cyts P450 by its redox partners, cyt P450 reductase and cyt b5. The short-term goals of this proposal, using both human and model cyts P450, are to understand the biochemical basis of how the redox partners of cyt P450 regulate its activity, substrate specificity, and catalytic mechanism. Experimental techniques, including site-directed mutagenesis, rapid quenching of cyt P450 activity by chemical means, and freezing, HPLC-mass spectrometry, and quantum mechanical/molecular mechanical calculations will be employed to elucidate how the activity of microsomal cyts P450 is regulated by its redox partners. Understanding how nature designs cyt P450 active sites is a fundamental question with implications for predicting and eventually modifying the routes of metabolism of a large number of environmental contaminants such as phthalates, bisphenol A, polychlorinated biphenyls (PCBs) and many currently used drugs, including chemotherapeutic agents, psychoactive compounds, and cardiovascular therapies. Knowledge of the molecular mechanism by which the activity of human cyts P450 can be regulated will also prove to be a tremendous asset in developing drugs and procedures to alter the large number of critical physiologic processes in which the human cyts P450 participate, as well as in designing less toxic and more specific therapeutic agents and prodrugs, especially chemotherapeutic agents and environmental contaminants.