SELECTIVE DESTRUCTION OF CYTOCHROME P-450 BY DRUGS

细胞色素P450酶催化生物合成中的关键步骤 胆固醇和所有其他类固醇，大多数药物和 外源物质，以及异源物质向致癌物质的不良转化 和有毒物种。这项计划的长期目标是 定义细胞色素P450酶的活性部位结构，以 阐明它们的催化机制，开发同工酶特异性的， 基于机理的灭活剂，并使用灭活剂 细胞色素P450的生物化学和生理学研究进展 系统。另一个主要目标是发展一个普遍的理论 血球蛋白功能。该项目的直接目标是：(A) 毫不含糊地建立各种类别的结构 可能有一个碳原子与血红素结合的细胞色素P450络合物 铁原子，(B)使用血红素络合物将光标记定位在 纯化的细胞色素P450同工酶的活性部位(特别是P450b，P450e， P450c、P450d和P450Law)以便获得关于蛋白质的信息 定义其活性部位的序列，(C)使用血红素络合物和N- 烷基血红素加合物以定义底物结合的拓扑结构和 单个细胞色素P450同工酶的催化部位，(D)更好地定义 细胞色素P450的催化机制，尤其是细胞色素P450 Pi-键氧化和该酶与 二烷基过氧化物，(E)继续发展同工酶专一性 特别强调脂肪酸的灭活剂， 前列腺素和二十烷类W-羟基酶，以及(F)继续使用 以机理为基础的灭活剂确定其生物学作用 细胞色素P450酶。

Cytochrome P450 enzymes catalyze key steps in the biosynthesis of cholesterol and all other steroids, the metabolism of most drugs and xenobiotics, and the undesirable conversion of xenobiotics to carcinogens and toxic species. The long term objectives of this project are to define the active site structures of cytochrome P450 enzymes, to elucidate their catalytic mechanisms, to develop isozyme-specific, mechanism-based inactivating agents for them, and to use the inactivating agents to explore the biochemistry and physiology of the cytochrome P450 system. A further major goal is to develop a general theory of hemoprotein function. The immediate aims of the project are to (a) unambiguously establish the structures of the various classes of cytochrome P450 complexes that may have a carbon atom bound to the heme iron atom, (b) use the heme complexes to position photolabels in the active sites of purified cytochrome P450 isozymes (notably P450b, P450e, P450c, P450d, and P450LAw) in order to obtain information on the protein sequences that define their active sites, (c) use heme complexes and N- alkyl heme adducts to define the topologies of the substrate binding and catalytic sites of individual cytochrome P450 isozymes, (d) better define the catalytic mechanism of cytochrome P450, in particular the mechanism of pi-bond oxidation and the reaction of the enzyme with dialkylperoxides, (e) continue the development of isozyme-specific inactivating agents with a particular emphasis on fatty acid, prostaglandin, and eicosanoid w-hydroxylases, and (f) continue to use mechanism-based inactivating agents to determine the biological roles of cytochrome P450 enzymes.