Abstract: Different carriers such as Sepharose CL-4B and seven kinds of macroporous resins were used to immobilize lipase Palatase 20000L. The lipase showed higher activity and better stablity when immpbilized on macroporous resin type HPD-600 compared with other carriers. Ressponse surface methodolgy was employed to optimize key conditions for the immobilization of lipase Palatase 20000L on macroporous resin type HPD-600 to achieve maximum immobilized lipase activity. The optimal immobilization conditions were found as follows: pH 3.9, enzyme-to-carrier ratio 9.1 mg/g, and adsorption time 1.8 h. Under these conditions, the immobilized lipase achieved its maximum activity, 1440 U/g and a rantivity ecovery above 50%. The optimal reacton temperature of the immobilized lipase was 50 ℃, the optimal reaction pH 8.0, and the Km value 0.130 g/mL, which was higher than that (0.069 g/mL) of the free form. Moreover, the immobilized lipase showed higher thermal stability and maitained over 58% of its original activity after the fifth repeated use.

Key words: lipase Palatase 20000L, immobilization, stability, response surface methodology