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All-atom molecular simulations and NMR experiments have been used to study the conformations and interactions of oxidized glutathione (GSSG) in aqueous solution. The simulations are characterized by the radius of gyration, intramolecular distance, root-meansquare deviation and solvent-accessible surface area. The variations in these properties show time dependences. Interestingly, the two chains connected by the disulfide linkage in GSSG show different flexibilities in aqueous solution. The conformations of GSSG can convert from "extended" to "folded" states. Also, the two different kinds of amide hydrogen atoms in cysteine (Cys) and glycin (Gly) show different capabilities in forming N-H· · ·O hydrogen bonds with water molecules. Temperature-dependent NMR results show agreements with the MD simulations.

All-atom molecular dynamics (MD) simulation and the NMR spectra are used to investigate the interactions in N-glycylglycine aqueous solution. Different types of atoms exhibit different capability in forming hydrogen bonds by the radial distribution function analysis. Some typical dominant aggregates are found in different types of hydrogen bonds by the statistical hydrogen-bonding network. Moreover, temperature-dependent NMR are used to compare with the results of the MD simulations. The chemical shifts of the three hydrogen atoms all decrease with the temperature increasing which reveals that the hydrogen bonds are dominant in the glycylglycine aqueous solution. And the NMR results show agreement with the MD simulations. All-atom MD simulations and NMR spectra are successful in revealing the structures and interactions in the N-glycylglycine-water mixtures.