Immobilization of catalase via adsorption onto L-histidine grafted functional pHEMA based membrane

Poly(2-hydroxyethylmethacrylate) (pHEMA) based flat sheet membrane was prep ared by UV-initiated photopolymerization technique. The membrane was then g rafted with L-histidine. Catalase immobilization onto the membrane from aqu eous solutions containing different amounts of catalase at different pH was investigated in a batch system. The maximum catalase immobilization capaci ty of the pHEMA-histidine membrane was 86 mug cm(-2). The activity yield wa s decreased with the increase of the enzyme loading. It was observed that t here was a significant change between V-max value of the free catalase and V-max value of the adsorbed catalase on the pHEMA-histidine membrane. The K -m value of the immobilized enzyme was higher 1.5 times than that of the fr ee enzyme. Optimum operational temperature was 5 degreesC higher than that of the free enzyme and was significantly broader. It was observed that enzy me could be repeatedly adsorbed and desorbed without loss of adsorption cap acity or enzyme activity. (C) 2001 Elsevier Science B.V. All rights reserve d.