Carbamoylation of peptides and proteins in vitro by S-(N-methylcarbamoyl)glutathione and S-(N-methylcarbamoyl)cysteine, two electrophilic S-linked conjugates of methyl isocyanate.
Carbamoylation of peptides and proteins in vitro by S-(N-methylcarbamoyl)glutathione and S-(N-methylcarbamoyl)cysteine, two electrophilic S-linked conjugates of methyl isocyanate.
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S-(N-甲基氨基甲酰基)谷胱甘肽和 S-(N-甲基氨基甲酰基)半胱氨酸（异氰酸甲酯的两种亲电子 S 连接缀合物）在体外对肽和蛋白质进行氨基甲酰化。
DOI：
10.1021/tx00022a007
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发表时间：
1991
影响因子：
4.1
通讯作者：
Baillie,TA
中科院分区：
文献类型：
--
作者：
Pearson,PG;Slatter,JG;Rashed,MS;Han,DH;Baillie,TA
本文用体外模型系统研究了S-（AT-甲基氨基甲酰基）谷胱甘肽（SMG），异氰酸甲酯的谷胱甘肽结合物和相应的半胱氨酸加合物S-（2 V-甲基氨基甲酰基）半胱氨酸（SMC）对肽和蛋白质的反应性。将SMC或SMC的三氘甲基类似物与还原或氧化形式的催产素一起孵育，得到类似的单-、双-和三-N-甲基氨基甲酰化肽的混合物。单和双加合物的结构解析的快速原子轰击串联质谱表明，氨甲酰化的催产素优先发生在Cys-6和Cys-1和/或Tyr-2的二级网站的修改。S-[AT-（[14 C]甲基）氨基甲酰基]谷胱甘肽（14 C-SMG）与天然牛血清白蛋白（BSA）孵育后，放射性以时间和浓度依赖性方式与蛋白共价结合。在将蛋白质暴露于14 C-SMG之前，以二硫化物形式“封闭”BSA的单独Cys-34硫醇基团未能显著降低该共价结合的程度或时间过程。可以得出结论，MIC的氨基甲酸酯硫酯缀合物是反应性的，氨基甲酰化的实体，其可以将MIC的元素捐赠给肽和蛋白质上的亲核官能团。游离硫醇似乎是这种氨甲酰化过程的优选位点，这种现象可能在MIC和相关异氰酸酯诱导的组织病变的病理学中具有重要的毒理学后果。
The reactivity toward peptides and proteins of S-(AT-methylcarbamoyl) glutathione (SMG), the glutathione conjugate of methyl isocyanate, and the corresponding cysteine adduct, S-(2V-methylcarbamoyl) cysteine (SMC), was investigated with the aid of in vitro model systems. Incubation of SMC or a trideuteriomethyl analogue of SMC with eitherthe reduced or oxidized forms of oxytocin afforded similar mixtures of mono-, bis-and tris-jV-methylcarbamoylated peptides. Structure elucidation of the mono and bis adducts by fast atom bombardment tandem mass spectrometry indicated that carbamoylation of oxytocin occurred preferentially at Cys-6 and that Cys-1 and/or Tyr-2 were secondary sites of modification. Upon incubation of S-[AT-([14C] methyl) carbamoyl] glutathione (14C-SMG) with native bovine serum albumin (BSA), radioactivity became bound covalently to the protein in a time-and concentration-dependent fashion.“Blocking” of the lone Cys-34 thiol group of BSA in the form of a disulfide prior to exposure of the protein to 14C-SMG failed to decrease significantly the extent or time course of this covalent binding. It is concluded that carbamate thioester conjugates of MIC are reactive, carbamoylating entities which can donate the elements of MIC to nucleophilic functionalities on peptides and proteins. Free thiols appear to be preferred sites for such carbamoylation processes, a phenomenon that may have important toxicological consequences in the pathology of tissue lesions induced by MIC and related isocyanates.