PROTEIN THIOLS AND MECHANISMS OF TOXICITY

1，2-二卤代乙烷和亚硫酸氢盐的毒性机理为 由Mosbaugh博士和Reed博士调查，主要目标是 阐明大分子的结构和功能变化 包括酶的保真度的丧失。两者的特定属性 蛋白质硫醇和为这些研究提出的烷化剂， 应该可以识别特定的蛋白质硫醇变化 由烷基化引起的，包括生物功能丧失和 蛋白质硫醇稳态的改变。基于以下因素： S对官能团的烷基化反应--(2-氯乙基)谷胱甘肽 与核酸和蛋白质相关的烷基化IF蛋白 分子被认为是致病机制的一个重要特征。 二氯乙烷的毒性。烷基化反应是通过生成 从CEG非酶分解中得到的一种反应性的表硫离子。它 提出了CEG对蛋白质的烷基化反应具有选择性 硫醇胜过其他官能团，甚至在蛋白质中具有选择性 含有硫醇的。此外，提议将主要部分的 1，2-二卤代乙烷的急性毒性与 由于这些烷基化事件，特定的蛋白质功能。 亚硫酸氢盐和亚硫酸盐与特定蛋白质的相互作用可能提供 多卤代芳烃或N-表现出的致癌性基础 甲基--N‘-硝基-N-亚硝胺。在生理条件下， 亚硫酸氢盐是一种既需要DNA损伤又需要DNA修复的共变剂 来诱导突变。我们建议调查DNA在多大程度上 聚合酶的保真度因形成磺酸盐加合物而改变(S)。 模型蛋白、碳酸氢酶III、白介素3、硫氧还蛋白和 DNA聚合酶将与CEG或亚硫酸氢盐反应，其结构 的共价加合物将通过电泳法、质量法鉴定 光谱，消化结合多肽表征和 量化。类似的研究将在细胞和体内进行 阐明1，2-二卤代乙烷和1，2-二卤代乙烷引起的主要蛋白质变化 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.