Improvement in extraction and catalytic activity of Mucor javanicus lipase by modification of AOT reverse micelle

Reverse micelles are formed in apolar solvents by spontaneous aggregation of surfactants. Surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT) is most often used for the reverse micellar extraction of enzymes. However, the inactivation of enzyme due to strong interaction with AOT molecules is a severe problem. To overcome this problem, the AOT/water/isooctane reverse micellar system was modified by adding short chain polyethylene glycol 400 (PEG 400). The modified AOT reverse micellar system was used to extract Mucor javanicus lipase from the aqueous phase to the reverse micellar phase. The extraction efficiency (E) increased with the increase in PEG 400 addition and the maximum E in PEG 400 modified system was twofold higher than that in the PEG 400-free system. Upon addition of PEG 400, the water activity (aw) of aqueous phase decreased, whereas aw of reverse micellar phase increased. The circular dichroism spectroscopy analysis revealed that PEG 400 changes the secondary and tertiary structure of lipase. The maximum specific activity of lipase extracted in PEG 400-modified reverse micellar system was threefold higher than that in the PEG-free system.