环 - L - 胱氨酸二硫键亲核取代反应的理论研究

Theoretical study of nucleophilic substitution at the disulfide bridge of cyclo-l-cystine.

作者信息

Bachrach Steven M, Chamberlin Adam C

机构信息

Department of Chemistry, Trinity University, 715 Stadium Drive, San Antonio, TX 78212, USA.

出版信息

J Org Chem. 2003 Jun 13;68(12):4743-7. doi: 10.1021/jo034046x.

DOI:10.1021/jo034046x

PMID:12790577

Abstract

The reaction of cyclo-l-cystine with thiolate is examined at the B3LYP/6-31+G level. The two isomers of cyclo-l-cystine differ in their dihedral angle about the disulfide bond; the M isomer (with dihedral angle of -90.1 degrees) is found to be slightly lower in energy. The nucleophilic substitution reaction at sulfur follows the addition-elimination mechanism, exemplified by the hypercoordinate sulfur intermediate on the reaction surface. The reaction is exergonic (DeltaG = -6.16 kcal mol(-1)), and both the entrance and exit transition state lie below the reactant energies.

摘要

在B3LYP/6-31+G水平下研究了环-1-胱氨酸与硫醇盐的反应。环-1-胱氨酸的两种异构体在二面角上关于二硫键有所不同；发现M异构体（二面角为-90.1度）能量略低。硫上的亲核取代反应遵循加成-消除机制，反应表面上的超配位硫中间体就是例证。该反应是放能的（ΔG = -6.16千卡摩尔⁻¹），并且入口和出口过渡态都低于反应物能量。