Immobilization of laccase on epoxy-functionalized macroporous SiO_2 block materials

A novel macroporous silica block material was epoxy-modified via post-grafting method under solvothermal conditions.The epoxy-functionalized macroporous silica were employed as the supports for immobilization of the commercial Novozymes laccase by using covalent binding method.Immobilization conditions were optimized,the properties of immobilized and free laccase were studied.The optimum conditions for immobilization of laccase were at the immobilization time of 4 h,the buffer of pH 4.5 and the initial laccase concentration of 25 mg /mL,under these conditions,the activity of immobilized laccase reaches 101.7 U /g.The optimum pH and temperature of immobilized laccase were 4.0 and 50 ℃,respectively.The experiments show that the immobilization significantly improves the pH stability and thermal stability of laccase.The immobilized laccase can be used repeatedly,and the remained activity was 43.4% after 10 times of reaction with the substrate.