PROTEIN THIOLS AND MECHANISMS OF TOXICITY

对1，2-二卤乙烷和亚硫酸氢盐的毒性机理进行了探讨 Mosbaugh博士和Reed博士的主要目的是 阐明大分子的结构和功能改变 包括酶保真度的损失。 两者的特性 为这些研究提出的蛋白质硫醇和烷基化剂， 应该可以确定特定的蛋白质巯基改变 包括生物学功能的丧失， 蛋白质巯基稳态的改变。 根据相对比率， 通过S-（2-氯乙基）谷胱甘肽（CEG）对官能团进行烷基化 与核酸和蛋白质相关，如果蛋白质 分子被认为是一个重要的特点机制， 二氯乙烷的毒性。 烷基化通过形成 CEG非酶分解产生的活性表锍离子 它 提出了CEG对蛋白质烷基化的选择性， 巯基优于其他官能团，甚至在蛋白质中具有选择性 含有硫醇。 此外，建议将大部分的 1，2-二卤乙烷的急性毒性与 由于这些烷基化事件而产生的特定蛋白质功能。 亚硫酸氢盐和亚硫酸盐与特定蛋白质的相互作用可以提供 多卤芳香族化合物或N--所显示的辅致癌性的基础 甲基--N'-硝基--N-亚硝基胍。 在生理条件下， 亚硫酸氢盐作为共诱变剂，需要DNA损伤和DNA修复 来诱导突变 我们建议调查DNA在多大程度上 聚合酶保真度通过形成磺酸盐加合物而改变。 模型蛋白，碳酸酐酶III，白细胞介素3，硫氧还蛋白，和 DNA聚合酶将与CEG或亚硫酸氢盐反应，并且结构 的共价加合物将通过电泳、质谱 光谱法和消化结合肽表征， 定量 将用细胞和体内进行类似的研究。 为了阐明1，2-二卤代乙烷引起的主要蛋白质改变， 亚硫酸氢盐。

The mechanisms of toxicity of 1,2--dihaloethanes and bisulfite will be investigated by Drs. Mosbaugh and Reed with the main objective being the elucidation of the structure and function alterations of macromolecules including loss of enzyme fidelity. The specific properties of both protein thiols and the alkylating agents proposed for these studies, should make it possible to identify specific protein thiol alterations that result from alkylation including loss of biological function and the alteration in protein thiol homeostasis. Based on the relative rates of alkylation by S--(2-chloroethyl)glutathione (CEG) of functional groups associated with nucleic acids and proteins, the alkylation if protein molecules is proposed to be an important feature of the mechanism of toxicity of ethyl dichloride. The alkylation occurs via the formation of a reactive episulfonium ion from CEG nonenzymatic decomposition. It is proposed that protein alkylation by CEG is selective both for protein thiols over other functional groups and even selective amongst proteins containing thiols. Further, it is proposed that a major portion of the acute toxicity of 1,2--dihaloethanes is associated with the loss of specific protein functions due to these alkylation events. Bisulfite and sulfite interaction with specific proteins may provide the basis for the cocarcinogenicity shown with polyhaloaromatics or N-- methyl--N'--nitro--N--nitrosoguanidine. Under physiological conditions, bisulfite acts as a comutagen requiring both DNA damage and DNA repair to induce mutations. We propose to investigate the extent to which DNA polymerase fidelity is altered by the formation of a sulfonate adduct(s). Model proteins, carbonic anhydrase III, interleukin 3, thioredoxin, and DNA polymerases will be reacted with CEG or bisulfite, and the structure of the covalent adducts will be identified by electrophoresis, mass spectrometry, and digestion combined with peptide characterization and quantitation. Similar studies will be conducted with cells and in vivo to elucidate the major protein alterations by the 1,2--dihaloethanes and bisulfite.