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， 化学反应代谢物，以表达其毒性。一个简单 模拟这种行为的化合物是溴苯，其反应性 代谢物与细胞蛋白质共价结合， 毒性与其结合力成正比。一个关键问题， 仍然没有答案的是"这些反应性的结构是什么？ 代谢物和它们与蛋白质形成的加合物？芳烃氧化物和 已知会形成醌代谢物，但两者都没有显示 最终绑定。这项研究的目的之一是回答 这个问题[C-14]-溴苯代谢物标记的蛋白质 将被水解、修饰的氨基酸分离出来并分析其结构 阐明。加合物谱将用于比较 治疗如酶诱导，其改变代谢， 毒性的溴苯，并比较加合物直接产生 溴苯对那些由其酚的次级代谢所产生的 代谢物。这将有助于确定那些加合物， 毒理学意义重大。本研究的第二个目标是 探讨微粒体环氧化物水解酶的解毒机制 溴苯-和其他环氧化物。酶的动力学同位素效应 氘标记S-（+）1和R-（-）-p-的水合作用 硝基苯乙烯氧化物，以及正在进行的相关模型研究，将是 确定并用于推导过渡态的几何形状， 酶反应。相应的亚胺（氮丙啶）类似物将是 作为底物和抑制剂进行研究，以探测 酶作用机制中的酸催化成分。连同现有 关于水作为特定的一般碱活化的信息 此外，拟议的研究应提供全面的情况， 这种重要酶的机制。

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.