Understanding the screening effect of aqueous DES on the IDPs: A molecular dynamics simulation study using amyloid...

Deep eutectic solvents (DESs) have emerged as the promising replacement to the ionic liquids in solvent engineering for bio-compatibility. We aim to understand the effect of aqueous deep eutectic solvents on the conformation of intrinsically disordered proteins (IDPs). In this context, we have studied the effect on amyloid beta (Aβ₄₂) monomer in the hydrated DES composed of tetrabutylammonium chloride and ethylene glycol in a 3:1 ratio using all-atom molecular dynamics simulations. DES is found to effectively screen the interaction of four zones of the amyloid beta monomer with water. Water molecules and the DES constituents modulate the local protein-solvent interactions, in the solvation shell of the protein. In addition, the aqueous DES medium conserves the secondary structure of the Aβ₄₂ monomer by increasing the intramolecular hydrogen bonding and D23-K28 salt-bridge interactions when compared to the pure water medium. The current study provides insights into the impact of DES in stabilizing an IDP, at molecular level. We envisage the hindered aggregation of the amyloid beta structures in DES medium over the pure water medium due to the screening of hydrophobic intramolecular interactions.