Conformations of Oxidized Glutathione in Aqueous Urea Solution by All-Atom Molecular Dynamic Simulations and 2D-NOESY Spectrum

All-atom molecular simulations and two-dimensional nuclear overhauser effect spectra have been used to study the conformations and interactions of oxidized glutathione (GSSG) in aqueous urea solution. The simulations were characterized by intramolecular distance, radius of gyration, solvent-accessible surface area, and root-mean-square deviation. Interestingly, the two chains connected by the GSSG disulfide linkage exhibited different flexibilities in the aqueous urea solution. GSSG can convert from “extended” to “folded” states in the simulations. Its preferred conformation in aqueous urea solutions is “extended”, which was confirmed by the 2D nuclear magnetic resonance (NMR) experiment. The two different types of amide hydrogen atoms in cysteine and glycine also showed different capacities to form N–H⋯O hydrogen bonds. The results were confirmed by temperature-dependent NMR experiment.