Inhibition mediated stabilization effect of imidazolium based ionic liquids on alcohol dehydrogenase

Ionic liquids (ILs) have gained increasing attention as solvents in chemical and biotechnological applications. Since alcohol dehydrogenases are of prime interest in industrial field, the present study has been conducted to study the influence of imidazolium based ionic liquids on kinetics, structure and stability of the thermophilic Thermoannerobacter brockii (TBADH) alcohol dehydrogenase. Our results exhibited that the ionic liquids could affect kinetic parameters and stability, but not the tertiary structure. Through the determination of inhibition profile, which revealed mixed inhibition, Ki (affinity of IL for the enzyme) and K-1 (affinity of IL for enzyme-substrate complex) values were calculated. Structural analysis using crystallographic data from protein data bank elucidated the structural details responsible for different responses of alcohol dehydrogenases toward ionic liquids. Finally, enhanced stability in [Mlm][Cl] was discussed. (C) 2012 Elsevier B.V. All rights reserved.