Does choline-based amino acid ionic liquid behave as a biocompatible solvent for stem bromelain structure?

Abstract

Abstract The potential of ionic liquids (ILs) as green solvent has opened burgeoning new areas of its application in various scientific and engineering fields. However, all ILs cannot be considered as “green solvent” due to toxicity and biodegradability issues associated with them. Therefore, the need of the hour is to synthesize green ILs in which efforts should be made to include cations and anions of the ILs from biological source. In this regard, choline glycine ([Ch][Gly]) has been synthesized in which both the ions belong to the bio-available sources. The stability and activity of stem bromelain (BM) have been studied in presence of choline bromide ([Ch][Br]) and [Ch][Gly]. The comparison of activity and stability of BM in both ILs have been performed using spectroscopic techniques and size parameter has been assessed using dynamic light scattering (DLS). On contrary to our expectation [Ch][Gly] proved to be a poor stabilizer for the BM when compared to [Ch][Br]. This can be due to the fact that in case of [Ch][Gly], Glycinate anions are forming strong H-bonds with the enzyme polypeptide backbone which dissociate the H-bonds that maintain the structural integrity of protein, while no such kind of interaction is present in case of [Ch][Br].