Molecular Dynamics Simulations and NMR Experimental Study of Oxidized Glutathione in Aqueous Solution

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-mean-square 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-Ha <-O hydrogen bonds with water molecules. Temperature-dependent NMR results show agreements with the MD simulations.