Improving the catalytic performance of porcine pancreatic lipase in the presence of [MMIm][MeSO4] with the modification of functional ionic liquids

Porcine pancreatic lipase (PPL) was chemically modified with various functional ionic liquids (ILs) to increase its catalytic performance in water-miscible IL. Catalytic activity and thermostability were tested with a p-nitrophenyl palmitate (pNPP) hydrolysis reaction. The native enzyme lost 18% of its initial activity in 0.4 M [MMIm][MeSO₄], whereas the activities of all the modified enzymes increased. The [HOOCBMIm][Cl] modification led to a 2-fold increase in activity in 0.3 M [MMIm][MeSO₄] than in aqueous. All the modified enzymes exhibited higher thermostability compared with the native enzyme at high temperature. In particular, the [HOOCBMIm][Cl] modification led to a 6-fold increase in thermostability at 60 °C. Conformational changes were confirmed by fluorescence spectroscopy and circular dichroism spectroscopy to elucidate the mechanism of catalytic performance alteration.