Protein renaturation by the liquid organic salt ethylammonium nitrate

The room-temperature liquid salt, ethylammonium nitrate (EAN), has been use d to enhance the recovery of denatured-reduced hen egg white lysozyme (HEWL ). Our results show that EAN has the ability to prevent aggregation of the denatured protein. The use of EAN as a refolding additive is advantageous b ecause the renaturation is a one-step process. When HEWL was denatured redu ced using routine procedures and renatured using EAN as an additive, HEWL w as found to regain 75% of its activity. When HEWL was denatured and reduced in near EAN, dilution resulted in over 90% recovery of active protein. An important aspect of this: process is that renaturation of HEWL occurs at co ncentrations of 1.6 mg/mL, whereas other renaturation processes occur at si gnificantly lower protein concentrations. Additionally, the refolded-active protein can be separated from the molten salt by simple desalting methods. Although the use of a low-temperature molten salt in protein renaturation is unconventional, the power of this approach lies in its simplicity and ut ility.