Comprehensive Evaluation of Biomolecular Interactions between Protein and Amino Acid Based-Ionic Liquids: A Comparable Study between [Bmim][Br] and [Bmim][Gly] Ionic Liquids

Protein is one of the most intricate and overriding biological system. Over the past years, there is an increased demand to consider ionic liquids (ILs) as novel biocompatible co-solvents for proteins. The overwhelming attention grabbed by new-generation amino acid ionic liquids (AAILs)'' among various fields of modern chemistry and biology, has been attributed to their unique and designer nature. However, the stability of proteins in such AAILs is still untouched. Therefore, we have synthesized 1-butyl-3-methylimidazolium glycine ([Bmim][Gly]) in which anion is directly derived from natural amino acid and characterized to improve the stability of stem bromelain (BM). Since, it is speculated that replacement of cation/anion with the amino acids (AAs) will improve the stability of protein. Therefore, the main aim of present work is to highlight the influence of [Bmim][Gly] on the conformational stability and activity of BM. Furthermore, enzyme's stability and activity arecompared with the conventional imidazolium-based ionic liquid i.e. 1-butyl-3-methylimidazolium bromide [Bmim][Br] by using spectroscopic techniques, enzyme assay and molecular docking. Our study shows that both studied ILs interact with functional groups of BM. As a result, in contrast to our expectation it appears that [Bmim][Br] stabilizes BM more than [Bmim][Gly]. We believe that present study will provide new insights into the interactions between enzyme and AAILs in the field of protein stabilization.