Covalent immobilization of invertase on microporous pHEMA–GMA membrane

Poly (2-hydroxyethyl methacrylate–glycidyl methacrylate) (pHEMA–GMA) membrane was prepared by UV-initiated photopolymerization. Invertase was immobilized by the condensation reaction of the epoxy groups of glycidyl methacrylate in the membrane structure with amino groups of the enzyme. The Km values were 22 mM and 58 mM for free and immobilized enzyme, respectively. Immobilization improved the pH stability and temperature stability of the enzyme. Thermal stability was found to increase with immobilization. The half times for the activity decay at 70 °C were found to be 11 and 38 min for the free and immobilized enzyme, respectively. The immobilized enzyme activity was found to be quite stable in later experiments.