Patterns of protein unfolding and protein aggregation in ionic liquids.

The objective of this study is to characterize the effect of ionic liquids (ILs) on the stability of proteins with regard to denaturation, protein aggregation and the formation of folding intermediates. Ribonuclease A was used as a model protein. A variety of ILs were tested. Detailed results are reported for choline dihydrogenphosphate, which enhances the thermal stability of the native state, and 1-ethyl-3-methylimidazolium dicyanamide, which acts as a strong denaturant. Varied factors include the intrinsic properties of the samples such as the IL concentration and the pH value as well as external factors such as incubation conditions. The time course of the deactivation processes was monitored. ILs can be used to suppress protein aggregation and steer the formation of intermediates.