Deep Eutectic Solvents: interaction with a biologically relevant peptide.

Deep Eutectic Solvents (DESs) are a new class of green solvents made by the complexation of a hydrogen bond-capable salt with a neutral hydrogen bond donor species. The rationale behind the present proposal is to seek to what extent a given DES can replace for water molecules in the salvation shell of a model peptide. To tackle this issue, we propose to investigate the structure of the solvation shell, at an atomistic level, of the tri-peptide Glutathione (GSH), a simple yet biologically-relevant peptide with anti-oxidant properties. Previous studies have highlighted the ability of water to distinguish two chemically identical carboxylate sites on the peptide, with the hydration shells differing both with respect to the number of water molecules and their spatial distribution around these sites. This unpredicted observation suggests different solvent accessibility for the carboxylate sites, a key factor for the early stages of protein folding and protein.ligand interactions. The proposed experiment should provide an answer to the following questions; are the asymmetric hydration shells observed for GSH in water, characteristic of water or their difference is due to the specific peptide sites? Can we alter the reduction/oxidation reaction leading to the oxidized GSH when GSH is in a DES?