| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Mechanism of Thiolate−Disulfide Interchange Reactions inBiochemistry
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Both density functional theory (DFT) (B3LYP) and CCSD ab initio calculations were employed in atheoretical investigation of the mechanism of thiolate−disulfide exchange reactions. The reaction pathwayfor degenerate thiolate−disulfide exchange reactions with dimethyl disulfide has been shown to proceedthrough a SN2-like transition structure that is very close in energy to the corresponding trisulfur anionicintermediate ([δ-S−S−Sδ-]). When relatively small substituents are involved, the level of theory mustbe increased to CCSD to make this rather subtle mechanistic distinction. With the more sterically hinderedexchange reaction involving t-butyl mercaptide and di-t-butyl disulfide, the potential energy surface exhibitsa distinct preference for the SN2 displacement pathway with an activation barrier of 9.8 kcal/mol. Whencorrections for solvent polarity are included (COSMO), an SN2 mechanism is also implicated in bothpolar and nonpolar solvents. DFT studies on thiolate−disulfide exchange, when the substituent is a modelpeptide, strongly support the intermediacy of a trisulfur intermediate that lies 10.7 kcal/mol below isolatedreactants. A well depth of this magnitude should provide a sufficient lifetime of the intermediate toaccommodate the requisite conformational adjustments that accompanies formation of the new disulfidebond.
|
| article type
| |
| is part of this journal
| |
