Immobilization of Laccase on Large-Sized SiO_2 Macroporous Materials

A large-sized SiO2 macroporous material modified by fixing Cu2+on its surface was employed as the support for the immobilization of laccase.The effects of immobilization time,pH value and the amount of enzyme provided on the immobilization were investigated,and the activity and stability of the immobilized enzyme were also studied.The results show that the adsorption equilibrium is reached after about 5 hours.The optimum conditions for immobilization of laccase were at the immobilization pH of 4.5 and the ratio of enzyme to support of 5 mg·g-1,and in this case,the activity recovery of the immobilized laccase is 100.4%.Comparing with the free laccase,both the optimum working pH and temperature of the immobilized laccase are higher and the ranges are wider.The experiments show that the immobilization improves the pH stability and the thermal stability of laccase significantly.The Km of the immobilized laccase is higher than the free laccase′ s.The immobilized laccase has good operational stability,the remained activity is 72.7% after 10 times of reaction with the substrate.