REACTIVE INTERMEDIATES IN METABOLISM AND DRUG TOXICITY

许多伤害细胞的药物和化学物质需要生物转化来 化学反应的代谢物来表达它们的毒性。一件简单的事 模拟这种行为的化合物是溴苯，它的活性 代谢物与细胞蛋白共价结合，引发 毒性与其结合力成正比。一个关键问题是 仍然没有回答的是，这些被动语态的结构是什么 代谢物及其与蛋白质形成的加合物？环氧芳烃和 已知有对苯二酚的代谢物形成，但都没有显示出来。 决定性地捆绑在一起。拟议研究的一个目标是回答 这个问题。用[C-14]-溴代谢物标记的蛋白质 将被水解、修饰的氨基酸分离出来并进行结构分析 已澄清。将使用加合物配置文件来比较 处理，如酶诱导改变新陈代谢和 溴苯的毒性，并比较直接产生的加合物 溴苯对其酚类二次代谢产生的影响 代谢物。这将有助于确定哪些加合物是最重要的 重要的毒物学。这项研究的第二个目标是 微粒体环氧化物水解酶解毒机制的探讨 溴苯和其他环氧化物。酶的动力学同位素效应 水合氢-，0-18和C-13标记的S-(+)1和R-(-)-p- 对于正在进行的相关模型研究，将 确定并用来推导出过渡态的几何形状 酶反应。相应的亚胺(氮杂环丙烷)类似物将为 作为底物和抑制物被研究以探查是否参与 酸催化成分在酶的作用机理中。与现有的 关于水的一般碱活化的信息作为特定的 总之，拟议的研究应该提供一个全面的图景。 这种重要酶的作用机制。

Many drugs and chemicals which injure cells require biotransformation to chemically reactive metabolites to express their toxicity. One simple compound which models this behavior is bromobenzene, whose reactive metabolites become covalently bound to cellular proteins, eliciting tocixity in direct proportion to their binding. A key question which remains unanswered is "what are the structures of these reactive metabolites and the adducts they form with proteins? Both arene oxide and quinone metabolites are known to form, but neither has been shown conclusively to bind. One objective of the proposed research is to answer this question. Proteins labelled with [C-14]-bromobenzene metabolites will be hydrolyzed, modified amino acids isolated and their structures elucidated. Adduct profiles will be used to compare the effects of treatments such as enzyme induction which alter the metabolism and toxicity of bromobenzene, and to compare adducts arising directly from bromobenzene to those arising from secondary metabolism of its phenolic metabolites. This will help identify those adducts which are most significant toxicologically. A second objective of this research is to probe the mechanism of microsomal epoxide hydrolase, which detoxifies bromobenzene- and other epoxides. Kinetic isotope effects for enzymic hydration of deuterium-, 0-18 and C-13 labelled S-(+)1 and R-(-)-p- nitrostyrene oxide, and for related model studies in progress, will be determined and used to deduce the geometry of the transition state for the enzymic reaction. The corresponding imine (aziridine) analog will be investigated as a substrate and inhibitor to probe for involvement of an acid-catalysis component in the enzyme mechanism. Together with existing information about general base activation of water as a specific cosubstrate, the proposed studies should furnish a comprehensive picture of the mechanism of this important enzyme.