Participation in Cytochrome b5 in Anesthetic Metabolism

描述(申请人提供)：细胞色素P450(细胞色素P450)是一个普遍存在的氧化酶超家族，其活性受第二种蛋白质细胞色素b5(Cyt B5)的影响。该项目的长期目标是了解Cytb5修饰人细胞色素P450介导的代谢的结构和机制基础，以便开发和使用策略来修饰这些重要同工酶的活性，以造福于人类。为了了解细胞色素b5在体内影响细胞色素P450氧化的分子机制，必须了解细胞色素b5如何与细胞色素P450相互作用，以及它如何改变细胞色素P450相对于细胞色素P450还原酶的催化循环。中青旅P450超家族有8000多名成员。它们存在于所有生物和植物王国中，被称为大自然的喷灯，因为它们能够氧化大量稳定的化学物质。人类拥有56种不同的细胞色素P450，其中许多对早期发育和生命本身是必不可少的。其他人类细胞色素P450决定了人类接触到的绝大多数治疗剂、致癌物和环境制剂的毒性、作用持续时间和消除。异种生物代谢的细胞色素P450也是大多数药物相互作用和药物不良反应的原因。第三组细胞色素P450负责必需内源性化合物的生物合成或代谢。这几乎包括所有类固醇(胆固醇、胆汁酸、雌激素、睾酮、皮质醇和维生素D)以及许多类脂和二十烷类化合物。细胞色素P450几乎存在于人类的每个器官和组织中。第二种蛋白质，细胞色素b5，调节人类和动物体内选定的细胞色素P450的生化机制和活性。事实上，细胞色素b5对细胞色素p450的睾酮生物合成是必不可少的，细胞色素p450目前是前列腺癌的治疗靶点。从实验中获得的知识将为理解细胞色素P450催化机制的体内调控奠定基础。虽然细胞色素P450与细胞色素b5的相互作用已经被深入研究，但我们的认识仍然存在重大差距。计划中的生化和结构实验的结果还将显著增强我们预测和最终修改大量环境污染物(如邻苯二甲酸酯、双酚A、多氯联苯)以及大量当前使用的药物(包括化疗药物、精神活性化合物和心血管疗法)的代谢途径的能力。人类细胞色素P450活性可以被调节的分子机制的知识也将被证明是开发药物和程序以改变56个人类细胞色素P450参与的大量关键生理过程的巨大财富。拟议的研究结果将被证明在设计毒性更低和更具体的治疗剂和前药，特别是化疗药物和环境污染物方面具有极高的价值。 与公共卫生相关：拟议中的研究将提供关于人类细胞色素P450活性如何受到第二种蛋白质--细胞色素b5的影响的研究，这些信息是人类细胞色素P450的活性如何被调节的，这是任何其他方法都不容易获得的重要新信息。拟议的研究还将提供更好的了解，不仅是药物代谢细胞色素P450的结构和功能，也是细胞色素P450在内源性化合物如睾酮、雌激素和二十烷类化合物代谢中的重要作用。这些关于人类细胞色素P450在其不同氧化还原伙伴在场的情况下的化学反应的信息将有助于新药的设计和开发，并增强研究人员在细菌和其他生物中通过基因工程改造细胞色素P450以产生化合物以改善人类福祉的能力。

DESCRIPTION (provided by applicant): The cytochromes P450 (cyts P450) are a ubiquitous superfamily of oxidases whose activity is influenced by a second protein, cytochrome b5 (cyt b5). The long-term goal of this project is to understand the structural and mechanistic basis of the modification of human cyt P450-mediated metabolism by cyt b5 in order to develop and employ strategies to modify the activity of these essential isozymes for human benefit. In order to understand the molecular mechanism by which cyt b5 influences oxidation by cyt P450 in vivo, one must understand the details of how cyt b5 interacts with cyt P450 and how it modifies the catalytic cycle of cyt P450 relative to cyt P450 reductase. There are more than 8,000 members of the cyts P450 superfamily. They are 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 exist in virtually every organ and tissue of humans. A second protein, cyt b5, modulates the biochemical mechanism and activity of selected cyts P450 in humans as well as animals. In fact, cyt b5 is essential for testosterone biosynthesis by a cyt P450 that is currently a therapeutic target for the treatment of prostate cancer. The knowledge gained from the proposed experiments will serve as the foundation for understanding the in vivo regulation of the catalytic mechanism of cyt P450. Although the cyt P450 interaction with cyt b5 has been intensely studied, significant gaps in our knowledge exist. The findings of the planned biochemical and structural experiments will also significantly enhance our ability to predict and eventually modify the routes of metabolism of a large number of environmental contaminants such as phthalates, bisphenol A, polychlorinated biphenyl (PCBs), and a vast number of 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 modulated 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 56 human cyts P450 participate. The results of the proposed studies will prove to be extremely valuable in designing less toxic and more specific therapeutic agents and prodrugs, especially chemotherapeutic agents and environmental contaminants. PUBLIC HEALTH RELEVANCE: The proposed studies on how the activity of three of the most important human drug metabolizing cytochromes P450 is affected by a second protein, cytochrome b5, will provide significant new information, not readily available by any others means, about how the activity of human cytochromes P450 is regulated. The proposed studies will also provide a better understanding of the structure and function of, not only drug metabolizing cytochromes P450, but also of cytochromes P450 that are important in the metabolism of endogenous compounds such as testosterone, estrogens, and eicosanoids. This information about the chemical reactivity of human cyts P450 in the presence of its different redox partners will facilitate the design and development of new drugs and enhance the ability of investigators to genetically engineer cyts P450 in bacteria and other organisms to produce compounds to enhance human welfare.