The recent expanded interest in applications of ionic liquids has developed into variety of investigations on the interactions between ionic liquids and biomolecules. Previous work has shown that ionic liquids, depending on their chemical composition, can affect protein stability. However, little is understood regarding the molecular mechanisms of stabilization or destabilization. We investigated the effects of aqueous solutions of sevral ionic liquids including BMIBF4, EMIAc, and PyrBF4 on the denaturation profile of myoglobin by the anionic detergent sodium dodecyl sulfate (SDS) and the zwitterionic detergent N,N-Dimethyl-N-dodecylglycine betaine (Empigen BB). Detergents traditionally unfold proteins through the disruption of hydrophobic contacts at the interior of the folded structure. The hypothesis was IF ionic liquids, or some component of the ionic liquids, were acting through a similar mechanism, the detergent mediated unfolding would be enhanced. A combination of absorbance, FRET, and circular dichroism spectroscopy were used to monitor unfolding. In all cases examined, the protein denaturation profile remained a traditional, cooperative process. In the case of SDS, we found that some ILs destabilize the protein structure, but the BMIBF4 had the greatest effect. Interestingly, the zwitterionic detergent N,N-Dimethyl-N-dodecylglycine betaine showed a more complex profile. In some cases, such as BMIBF4, ionic liquids that destabilized protein structure to unfolding by SDS became more resistant to unfolding by N,N-Dimethyl-N-dodecylglycine betaine.

Detergent mediated unfolding of proteins in the presence of ionic liquids

252nd National Meeting (2016)

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