Conformational analysis of ethyl mercaptan as a model of glutathione and its oxidation by peroxide: an exploratory first principle molecular computational study

First principle quantum molecular computations were carried out using Restricted Hartree-Fock method utilizing the 3-21G level of theory (RHF/3-21G) on ethyl mercaptan (Et-SH) and diethyl disulfide (Et-SS-Et) to study their full conformational space. The axis chirality associated with the rotation about the S-S linkage has been related to the potential energy hypersurface of diethyl disulfide. The energetics of the redox reaction Et-SH + H2O2 + HS-Et ? 2H2O + Et-S-S-Et was chosen to be a mimic of the biologically important redox reactions of glutathione (G-SH +H2O2 + HS-G ? 2H2O + G-S-S-G). Using first principle molecular computations, the redox reaction of Et-SH ? Et-S-S-Et has been found to be exothermic. Depending on the conformers involved, the exothermicity computed at the RHF/3-21G level of theory ranges from -62.0 kCal mol-1 to -64.2 kCal mol-1.