Improvement of catalytic properties of lipase from Arthrobacter sp. by encapsulation in hydrophobic sol-gel materials.

In this work, lipase from Arthrobacter sp. was immobilized by sol-gel encapsulation to improve its catalytic properties. Various silanizing agents including vinyl-trimethoxy silane, octyl-trimethoxy silane, gamma-(methacryloxypropyl)-trimethoxy silane (MAPTMS) and tetraethoxysilane (TEOS) were chosen as the precursors. Among them, MAPTMS was for the first time utilized to encapsulate lipases, and the prepared enzyme by copolymerization of MAPTMS and TEOS exhibited the highest activity in both the hydrolysis of p-nitrophenyl palmitate and the asymmetric acylation of 4-hydroxy-3-methyl-2-(2-propenyl)-2-cyclopenten-1-one. The effects of various immobilization parameters were investigated. Under the optimum conditions of MAPTMS/TEOS=1/1 (mol/mol), water/silane molar ratio (R value)=20 and lipase loading=0.01 g/mL sol, the total activity of the immobilized enzyme reached up to 13.6-fold of the free form. Moreover, the encapsulated lipase exhibited higher thermal stability than the free form and retained 54% of the original activity after uses for 60 d. Enantioselectivity of enzyme was also improved with an E value of 150 after encapsulation from 85 for the free form.