Exploring the behavior of Candida antarctica lipase B in aqueous mixtures of an imidazolium ionic liquid and its surfactant analogue

Abstract

The performance of Candida antarctica lipase B (CALB) has been evaluated in 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄)/water mixtures in a wide range of molar fractions (${\chi }_{BMIMBF4}$) with and without 1-dodecyl-3-methylimidazolium tetrafluoroborate (C₁₂-MIMBF₄), a surfactant derived from BMIMBF₄. The main aim of this work is to evaluate the influence of ${\chi }_{BMIMBF4}$ over micellar aggregates to assess the activity of enzymatic reactions. The investigated reaction corresponds to the hydrolysis of the substrate p-nitrophenyl laureate in each ${\chi }_{BMIMBF4}$. The kinetic study for ${\chi }_{BMIMBF4}$ at around 0.2 proved to be a border point in enzymatic activity. At ${\chi }_{BMIMBF4}$ = 0.1, the lipase activity increases in the presence of C₁₂-MIMBF₄. However, at higher concentrations, BMIMBF₄ has a negligible effect over the lipase activity. These results suggest specific interactions between water and BMIMBF₄ molecules in relation to CALB. This research highlights the superactivity phenomenon driven by the reaction media and the micelle interface. In this interfacial interaction, BMIMBF₄ acts directly on the changes induced on the enzyme upon its interaction with the micellar interface. This study opens a green perspective toward the biocatalysis field.

Keywords: catalysis; enzyme; ionic liquids; superactivity; surfactant.