Water-protein interactions play an important role in determining protein structure and function. A description at the atomic scale of hydration provides insights on important issues like protein folding and association as well as protein-ligand binding. We have looked at the interaction between water and specific groups of the tripeptide Glutathione (GSH, an important intracellular anti-oxidant), with a NDIS experiment combined with a EPSR simulation. Results indicate an unpredicted difference between the hydration shells of two chemically-identical carboxylate groups of GSH. In addition, a rather weak hydrogen bond between the thiol group of GSH and its first neighbor water molecule has been observed. The extensive hydrogen bond capacity shown by many ionic liquids (IL), raises important issues, such as that related to the possibility for a protic IL to replace water as a solvent.