Enhancement of activity of sol–gel immobilized lipase in organic media by pretreatment with substrate analogues

By performing pretreatment with substrate analogues, an activation of lipase immobilized into organic–inorganic hybrid silicate was attempted in esterification of menthol with butyric acid in organic media. With decreasing water content of immobilized lipase preparations, the activity of immobilized lipases by (−)-menthol pretreatment was enhanced, and the highest activity was obtained at water activity, aw=0.11. However, the pretreatment of immobilized lipases with (−)-menthol could not improve the enantioselectivity. In addition, the activity of pretreated immobilized lipases increased with increasing the chain length of alcohol as a substrate analogue. Consequently, it was found that hydrophobic and bulky alcohol was an effective substrate analogue to activate immobilized lipases.