Immobilization of Candida antarctica lipase B onto Purolite MN102 and its application in solvent-free and organic media esterification.

The aim of this study was to develop simple and efficient method for immobilization of Candida antarctica lipase B onto hydrophobic anion exchange resin Purolite MN102 and to apply immobilized catalyst for the enzymatic synthesis of two valuable esters-isoamyl acetate and L-ascorbyl oleate. At optimized conditions (1 M phosphate buffer pH = 7, 7 h at 25 °C, and 18.75 mg of offered proteins g of support), immobilized lipase with hydrolytic activity of 888.4 p-nitrophenyl butyrate units g was obtained. Afterwards, preparation was applied for the solvent-free synthesis of isoamyl acetate from triacetin and isoamyl alcohol. At 75 °C, 1 M of isoamyl alcohol, and 6 mg ml of enzyme 100 % yield was achieved in 6 h, while at prolonged reaction times, complete conversion was enabled even at lower temperatures, lower lipase loadings, and higher substrate concentrations. After 15 consecutive reuses (60 h), activity of catalyst dropped to 50 % of its initial value and total amount of 1.31 mol (170.55 g) of ester with 1 g of biocatalyst was produced. Even higher operational stability of lipase (25 % loss of activity in 200 h) was observed in the synthesis of L-ascorbyl oleate performed in organic solvent (t-butanol). Multiple use of one batch of immobilized biocatalyst in both cases led to a significant process cost reduction and substantial increment of corresponding productivities.