Impact of ionic liquids on conformational changes of bovine serum albumin - a fourier transform infrared spectroscopic study

Abstract

Ionic liquids (ILs) are low melting salts composed of an organic cation and an inorganic or organic anion. Ionic liquids are of interest for their wide range of applications and unique properties, such as the negligible vapor pressure of some types of ionic liquids, and the ability to modify ionic liquid properties by selection of the cation or anion. It has been hypothesized that over one million binary ionic liquids (meaning a single cation/anion pair) are possible. Due to the vast number of potential combinations, it should be possible to design ionic liquids specifically for an application of interest. Ionic liquids not only provide a novel and highly competent reaction medium, that is the solvent, but they also serve as efficient participants in a variety of chemical and biological reaction processes. However, there is a little understanding on how ionic liquids affect proteins. Here, we investigated the impact of different ionic liquids as a function of their alkyl chain length of the cationic moiety and concentrations on the conformational changes of the Bovine Serum Albumin (BSA) protein. In this work, we focused on the alternation in the secondary structures of the model protein. Fourier Transform Infrared (FTIR) spectroscopy is used to examine the changes in the secondary structure of BSA on varying concentration of a particular ionic liquid from 0 M to 1.0 M. It is observed that on increasing the concentrations of particular ionic liquid, structured regions are transformed to unstructured regions and thereby, assisting protein unfolding. Similarly, a gradual disruption of the native structure of BSA is observed with increase in the alkyl chain length of ionic liquids.