Protein stability analysis in ionic liquids by 19F NMR

Ionic liquids have been extensively used as environmentally friendly solvents for enzymatic reactions and other biological systems. Understanding the mechanism of how ionic liquids affect protein stability is crucial for the biological reaction processes and protein storage using ionic liquids as solvents. Although effects of ionic liquids on protein stability have been studied, equilibrium thermodynamics of protein stability in ionic liquids has not been quantitatively measured. Herein, we utilized 19 F NMR to measure the equilibrium thermodynamics of protein stability in ionic liquid [C 4 -mim]Br. Our results show that proteins are significantly destabilized in [C 4 -mim]Br ionic liquids. Our results suggest that 19 F NMR provides a simple and effective way to study the thermodynamics of protein stability in ionic liquids. 19 F NMR will be applicable to facilitate the protein–protein interaction study in ionic liquids. Graphical abstract