Comparative Electrochemical Behavior of Cytochrome c on Aqueous Solutions Containing Choline-Based Room Temperature Ionic Liquids

Ionic liquids have been attracting considerable interest in wide diverse fields, including biotechnology applications. Metalloproteins’ stability in such media is still a controversial subject. Divergent reports on the metalloproteins’ stability have been published, although hydrated ionic liquids seem more beneficial for achieving efficient redox transitions with the proteins’ redox centers. In the present study the electrochemical behavior of Cyt c in three choline-based ionic liquids aqueous solutions, namely choline dehydrogenophosphate ([Ch][DHP]), choline 2-(N-morpholino)ethanesulfonic acid ([Ch][MES]) and choline 3-(cyclohexylamino)-1-propanesulfonic acid ([Ch][CAPS]) was investigated. Cyt c formal potential and its temperature dependence, the diffusion coefficient and heterogeneous electron transfer rate were evaluated by cyclic voltammetry. The results show that Cyt c in aqueous solutions of [Ch][DHP] and [Ch][MES], retain its intrinsic redox properties.