Improving Catalytic Performance of Burkholderiacepacia Lipase by Chemical Modification with Functional Ionic Liquids

Various imidazolium and choline-based functional ionic liquids(ILs) comprising different cations and anions were grafted onto Burkholderiacepacia lipase(BCL) through surface amino acids coupling. The catalytic activity, thermostability, organic solvent tolerance and adaptability to temperature and pH changes of the modified BCL were then evaluated in olive oil hydrolysis reaction. The results showed that different combinations of cations and anions in ILs had important influence on the catalytic performance of the modified lipases. BCL modified with IL[Choline] [H₂PO₄] was the most improved lipase, in which increases by 1.2 folds in relative activity, 2.5 folds in typical proton solvent(10% methanol, volume fraction), and 1.4 folds in thermostability(after incubation at 70℃ for 2 h) were achieved in relative toits native form. BCL modified with[HOOCEPEG₃₅₀IM] [BF₄] had higher optimal tempe-rature and pH, and better thermosability compared with the native and other modified BCLs. The conformational changes of BCLs were also confirmed by fluorescence spectroscopy and circular dichroism spectroscopy.