引用本文:
【打印本页】   【HTML】   【下载PDF全文】   查看/发表评论  【EndNote】   【RefMan】   【BibTex】
←前一篇|后一篇→ 过刊浏览    高级检索
本文已被:浏览 1833次   下载 3760 本文二维码信息
码上扫一扫!
分享到: 微信 更多
多肽合成中半胱氨酸选择性脱硫的反应机理
田燕,王莉,石景*,于海珠*
作者单位E-mail
田燕 安徽农业大学应用化学系合肥230036  
王莉 安徽农业大学应用化学系合肥230036  
石景* 中国科学技术大学化学系合肥230026 shijing@ustc.edu.cn 
于海珠* 安徽大学化学化工学院合肥230601  
摘要:
基于自由基机理的半胱氨酸残基的选择性脱硫方法是多肽合成中实现丙氨酸连接位点的一种有效的策略. 运用密度泛函理论方法对这一脱硫过程的反应机理进行详细的理论研究. 计算结果表明, 硫醇基团的选择性脱硫经历了三个反应步骤:在自由基引发剂VA-044作用下失去巯基H原子;与还原剂三羧甲基磷酸作用脱除S原子;生成RH分子(伴随有RS自由基的产生). 其中,第二步脱除S原子过程为该反应的决速步骤. 同时添加物t-BuSH分子的加入促进了RS 自由基的产生,从而在一定程度上促进了半胱胺残基的选择性脱硫进程.
关键词:  半胱氨酸,脱硫,反应机理,密度泛函
DOI:10.1063/1674-0068/28/cjcp1501009
分类号:
基金项目:
Desulfurization Mechanism of Cysteine in Synthesis of Polypeptides
Yan Tian,Li Wang,Jing Shi*,Hai-zhu Yu*
Abstract:
The free-radical-based selective desulfurization of cysteine residue is an e cient protocol to achieve ligations at alanine sites in the synthesis of polypeptide and proteins. In this work, the mechanism of desulfurization process has been studied using the density functional theory methods. According to the calculation results, the desulfurization of the thiol group occurs via a three-steps mechanism: the abstraction of hydrogen atom on the thiol group with the radical initiator VA-044 (2,2′-azobis[2-(2-imidazolin-2-yl)propane]dihydrochloride), the removal of S atom under the reductant TCEP (tris(2-carboxyethyl)phosphine), and the formation of RH molecule (with the regeneration of RS radical). The second step (desulfurization step) is the rate-determining step, and the adduct t-BuSH facilitates the desulfurization of cysteine via bene ting the formation of the precursor of the desulfurization step.
Key words:  Cysteine, Desulfurization, Reaction mechanism, Density functional theory