Enhanced Stability of the Model Mini-protein in Amino Acid Ionic Liquids and Their Aqueous Solutions

TL;DR

This study uses molecular dynamics to show that amino acid ionic liquids enhance mini-protein stability and reduce conformational flexibility, potentially protecting proteins from thermal denaturation.

Contribution

It demonstrates that amino acid ionic liquids improve mini-protein stability and alter solvation dynamics, a novel insight into protein preservation in such solvents.

Findings

AAILs increase mini-protein stability.

Complete water replacement with AAILs hinders protein flexibility.

Amino acid anions dominate the protein's first coordination sphere.

Abstract

Using molecular dynamics simulations, the structure of model mini-protein was thoroughly characterized in the imidazolium-based amino acid ionic liquids and their aqueous solutions. We report that the mini-protein is more stable when AAIL is added as a cosolvent. Complete substitution of water by organic cations and anions further results in hindered conformational flexibility of the mini-protein. This observation suggests that AAILs are able to defend proteins from thermally induced denaturation. We show by means of radial distributions that the mini-protein is efficiently solvated by both solvents due to agood mutual miscibility. However, amino acid based anions prevail in the first coordination sphere of the mini-protein.