Enol-to-keto tautomerism of peptide groups
Enol-to-keto tautomerism of peptide groups
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DOI：
10.1021/jp056250p
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发表时间：
2006-03-09
影响因子：
3.3
通讯作者：
Oshiyama, A
中科院分区：
文献类型：
--
作者：
Kamiya, K;Boero, M;Oshiyama, A
基于密度泛函的模拟，对聚甘氨酸含有烯醇肽基团[-C（OH）N-]，这是一个结构异构体的酮形式[-CONH-]，表明在烯醇-酮互变异构反应，烯醇肽基团是不稳定的比酮形式，烯醇-酮互变异构的特征在于C-N肽键的顺/反异构化。在顺式/反式异构化的限速步骤是从O到N原子的肽基团的氢迁移与过渡态组成的四元环的顺式构型。顺式/反式异构化途径的分析表明，顺式/反式异构化的机制是本质上不同的烯醇和酮的形式。
Density functional based simulations, performed on polyglycine containing an enol peptide group [-C(OH)N-] which is a structural isomer of a keto form [-CONH-], show that in the enol-to-keto tautomeric reaction, the enol peptide group is less stable than the keto form, and that the enol-to-keto tautomerism is characterized by a cis/trans isomerization of the C-N peptide bond. The rate-limiting step in the cis/trans isomerization is a hydrogen migration from O to N atoms in the peptide group with a transition state consisting of a four-membered ring in the cis configuration. An analysis of the cis/trans isomerization pathway shows that the mechanisms for the cis/trans isomerization are essentially different between the enol and keto forms.