Immobilization of catalase in poly(isopropylacrylamide-co-hydroxyethylmethacrylate) thermally reversible hydrogels

✍ Scribed by Arıca, M Yakup; Öktem, H Avni; Öktem, Zeki; Tuncel, S Ali

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 113 KB
• Volume: 48
• Category: Article
• ISSN: 0959-8103
• DOI: 10.1002/(sici)1097-0126(199909)48:9<879::aid-pi237>3.0.co;2-n

✦ Synopsis

Catalase was entrapped in thermally reversible poly(isopropylacrylamide-co-hydroxyethylmethacrylate) (pNIPAM/HEMA) copolymer hydrogels. The thermoresponsive hydrogels, in cylindrical geometry, were prepared in an aqueous buffer by redox polymerization. It was observed that upon entrapment, the activity retention of catalase was decreased between 47 and 14%, and that increasing the catalase loading of hydrogel adversely affected the activity. The kinetic behaviour of the entrapped enzyme was investigated in a batch reactor. The apparent kinetic constant of the entrapped enzyme was determined by the application of Michaelis±Menten model and indicated that the overall reaction rate was controlled by the substrate diffusion rate through the hydrogel matrix. Due to the thermoresponsive character of the hydrogel matrix, the maximum activity was achieved at 25 °C with the immobilized enzyme. The K m value for immobilized catalase (28.6 mM) was higher than that of free enzyme (16.5 mM). Optimum pH was the same for both free and immobilized enzyme. Operational, thermal and storage stabilities of the enzyme were found to increase with immobilization.