The impact of fluorinated ionic liquids aggregation in the interactions with proteins

Proteins have wide biological activities facilitating their employment in several applications from academia to industry. Their implementation depends on costly downstream processes yielding proteins with high purity, stability, and activity. Ionic liquids (ILs) have emerged in the field of protein extraction and purification as an asset due to the possibility to fine-tune the ILs properties to a specific process. However, there is a lack of information concerning the interactions between ILs and proteins to guide the selection of the best ILs for these bottom-line applications. In this work, fluorinated ionic liquids (FILs) were used to infer the interactions with different proteins. FILs have enhanced solubilization mechanisms as a consequence of their rich aggregation behavior due to their amphiphilic character, which can aid the performance of FILs in protein extraction and purification. In this work, the determination of the FILs diffusion coefficients using NMR experiments has provided new information on the size and structure of the different aggregates in their entire range of concentration with water. Therefore, B1 immunoglobulin binding domain of streptococcal protein G (GB1), Bacillus subtilis lipase A (BSLA), and interferon-alpha 2b (IFN-α 2b) were selected to study the interactions between FILs and proteins. From a broad screening of FILs, it was possible to conclude which structural features are contributing to the interaction with the three proteins. This study constitutes an important first step in guiding the selection of appropriate FILs for protein applications.