Interaction of trehalose and glucose with a peptide beta-turn in aqueous solution

The issue of the interaction of carbohydrates with a peptide beta-turn is tackled by investigating at the atomic scale the interaction of glucose and trehalose with an aqueous solution of Glycyl-L-prolyl-glyci namide center dot HCl. The study, performed by neutron diffraction with isotopic substitution augmented by Monte Carlo simulation analysis, evidences clear differences between the two systems. Indeed, while trehalose confines water within the hydration shell of the solute, glucose enters this shell, in competition with water molecules. As a result, the structure of beta-turns in aqueous solution is stretched in presence of glucose as co-solute. This observations may be the key to distinguish the protection mechanism against drought from that against osmotic pressure. (C) 2022 Elsevier B.V. All rights reserved.