Urea and guanidine salts as novel components for deep eutectic solvents

Abstract

We present guanidinium salts in combination with urea, used to prepare a new combination of deep eutectic solvents (DES). They have recently attracted much attention as “green” alternatives to conventional organic solvents in various fields including biophysical chemistry. These were subsequently used to test the stability and solubility of proteins in a water-free DES. We performed CD analyses in order to monitor global secondary and tertiary structural changes of cytochrome c in the presence of Guanidine HCl–urea. Formation of the melt form of DES at a room temperature was an effective way to store soluble protein in the denatured form for a long time. Consequent dialysis allows one to recover proteins into their native form.