Reversible immobilization of Candida rugosa lipase on fibrous polymer grafted and sulfonated p(HEMA/EGDMA) beads

Poly(2-hydroxyethyl methacrylate/ethylenglycol dimethacrylate) beads were grafted with poly(glycidylmethacrylate) via surface initiated atom transfer radical polymerization. Epoxy groups of the grafted polymer were modified in to sulfone groups. Sulfonated beads were characterized by swelling studies, FT-IR, SEM and elemental analysis, and were used for reversible immobilization of lipase. Under given experimental conditions, the beads had an adsorption capacity of 44.7 mg protein/g beads. The adsorbed lipase on beads retained up to 67.4% of its initial activity. The immobilized lipase exhibited improved thermal and storage stabilities over those of the free enzyme. The immobilized lipase could desorb 1.0 M NaCl solution at pH 8.0, and the sulfonated beads can be repeatedly charged with fresh enzyme after inactivation upon use.