SELECTIVE DESTRUCTION OF CYTOCHROME P-450 BY DRUGS

细胞色素P450酶催化生物合成的关键步骤， 胆固醇和所有其他类固醇，大多数药物的代谢， 外源性物质，以及外源性物质转化为致癌物质的不良反应 有毒的物种。 该项目的长期目标是 定义细胞色素P450酶的活性位点结构，以 阐明其催化机制，开发同工酶特异性， 用于它们的基于机理的灭活剂，并且使用灭活剂， 探索细胞色素P450的生物化学和生理学的试剂 系统 另一个主要目标是发展一个通用理论， 血红蛋白功能 该项目的近期目标是：（a） 明确地建立各种类别的结构， 可能具有与血红素结合的碳原子的细胞色素P450复合物 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同工酶的活性位点（特别是P450 b，P450 e， P450 c、P450 d和P450 LAw），以获得关于蛋白质的信息 定义其活性位点的序列，（c）使用血红素复合物和N- 烷基血红素加合物，以限定底物结合的拓扑结构， 单个细胞色素P450同工酶的催化位点，（d）更好地定义 细胞色素P450的催化机制，特别是 π键的氧化和酶与 二烷基过氧化物，（e）继续发展同工酶特异性 灭活剂，特别强调脂肪酸， 前列腺素和类花生酸W-羟化酶，和（f）继续使用 基于机制的灭活剂，以确定生物作用 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.