Flexible immobilization of lipase on hydrophilic and comblike polymer support containing epoxy group

A hydrophilic and comblike polymer support PS-acyl-P(acrylamide-co-glycidyl methacrylate) containing epoxy groups for flexible and covalent immobilization of lipase has been prepared by an atom transfer radical polymerization method. The grafting reaction of glycidyl methacylate and hydrophilic acrylamid was initiated from the chloroacetyl groups on the styrene-divinylbenzene copolymer microspheres with CuCl and 2, 2'-bipyridine complex as a catalyst. The apparent activity of lipase immobilized on PS-acyl-P(acrylamide-co-glycidyl methacrylate) was 16.6 U/g, and the optimal temperature and pH were 45-55 ^oC and 8.5 for hydrolysis of p-nitrophenyl palmitate, respectively. The immobilized lipase was stable in the range of pH = 5-10 and at temperature below 80 ^oC. The operational stability for the immobilized lipase was tested for consecutive hydrolysis of p-nitrophenyl palmitate. The result shows that the immobilized lipase has excellent operational stability. The residual activity of immobilized lipase was 73.5% after used 7 cycles. The activity of immobilized lipase remained 86.8% of the origin after storage at 4 ^oC for 60 d. Lipase got improved to varying degrees for organic solvent tolerance through immobilization on PS-acyl-P(acrylamide-co-glycidyl methacrylate).