1University of Delhi, Delhi, India
Ionic Liquids as green solvents for enhanced stability of proteins against multiple stresses
Department of Chemistry, University of Delhi, Delhi-110 007, India
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Ionic liquids (ILs) have evolved as novel solvent systems fulfilling the requirements of biotechnology and bioengineering. In recent years, large numbers of ILs have been synthesized and their effect on protein stability has been illustrated. However, harsh process conditions, such as temperature, pH, and presence of organic solvents, are the major barriers to the effective use of enzymes in biocatalysis. We demonstrate the suitability of ILs as potential media for enzymes, in which remarkable enhanced activity and improved stability of proteins against multiple stresses were obtained. The catalytic activity of the enzyme in presence of ILs was retained against several external stimulus, such as chemical denaturants (H2O2 and GuHCl), and temperatures up to 120 °C. The observed enzyme activity is in agreement with its structural stability, as confirmed by UV–Vis, circular dichroism (CD), and Fourier transform infrared (FT-IR) spectroscopies. Finally, it is demonstrated that protein can be successfully recovered from the aqueous solution of ILs and reused without compromising its yield, structural integrity and catalytic activity, thereby overcoming the major limitations in the use of IL-protein systems in biocatalysis.