BIOACTIVATION OF HALOGENATED HYDROCARBONS

描述：许多卤代烃是令人感兴趣的，因为它们 高产量和证明的致癌能力， 实验动物卤乙烯三氯乙烯（TCE）可活化 通过氧化或结合;本提案的重点将是氧化 和关键产品TCE氧化物。TCE氧化物水解的机理将是 使用动力学和同位素标记模式建立。反应产物 由蛋白质和DNA形成的，将以工作假设为特征， 酰基卤是反应的主要亲电试剂。二卤甲烷 （CH 2X2）通过酶促谷胱甘肽（GSH）缀合而活化。的 CH 2X2衍生的GSH-DNA加合物的表征将使用质量 光谱法，工作扩展到体外环境与二氯甲烷。大鼠和 人GSH转移酶将与 细菌类似物（DM 11），其允许嗜甲基菌在CH 2Cl 2上生长。这 CH 2X2化合物之间的构效关系， 有助于建立缀合机制，并确定GSCH 2X或HCHO是否是 基因毒性产物（CH 2X2）。其他工作将包括寻找 4-碳双功能亲电试剂衍生的含GSH的DNA加合物 (e.g.丁二烯二环氧化物）作为细菌增强的解释 通过GSH转移酶表达突变。与二溴化乙烯（EDB）的合作将 包括（i）用鸟苷完成细菌定点诱变工作 N2-、N7-和O 6-CH 2CH 2SG加合物，以确定 每个和（ii）分析的基础上O 6-烷基鸟嘌呤转移酶增加 EDB（和CH 2Br 2）的致突变性。这些涉及酶的实验 氧化和共轭反应旨在帮助定义重要的 这些概念可以应用于其他卤代烃和其他 也有致癌的化学物质。

DESCRIPTION: Many halogenated hydrocarbons are of interest because of their high production volume and demonstrated ability to cause cancers in experimental animals. The vinyl halide trichloroethylene (TCE) can be activated via oxidation or conjugation; the focus in this proposal will be on oxidation and the key product TCE oxide. The mechanism of TCE oxide hydrolysis will be established using kinetics and isotope labeling patterns. Reaction products formed with proteins and DNA will be characterized with the working hypothesis that acyl halides are the major electrophiles that react. Dihalomethanes (CH2X2) are activated by enzymatic glutathione (GSH) conjugation. The characterization of CH2X2-derived GSH-DNA adducts will be done using mass spectrometry, with work extended to in vitro settings with CH2Cl2. Rat and human GSH transferases will be compared (in terms of DNA adduction) with a bacterial analog (DM11) that allows for growth of Methylophilus on CH2Cl2. This work and structure-activity relationships among CH2X2 compounds will be done to help establish the conjugation mechanism and to determine if GSCH2X or HCHO is the genotoxic product (of CH2X2). Other work will involve a search for GSH-containing DNA adducts derived from 4-carbon bifunctional electrophiles (e.g. butadiene diepoxide) as an explanation for enhancement of bacterial mutation by GSH transferase expression. Work with ethylene dibromide (EDB) will involve (i) completion of bacterial site-directed mutagenesis work with guanyl N2-, N7-, and O6-CH2CH2SG adducts to determine the relative contributions of each and (ii) analysis of the basis of O6-alkylguanine tranferase-increased mutagenicity of EDB (and CH2Br2). These experiments involving enzymatic oxidation and conjugation reactions are intended to help define important concepts that can be applied to other halogenated hydrocarbons and to other cancer suspect chemicals as well.