Covalent immobilization of catalase onto eupergit, florisil and glass carriers and characterization of immobilized catalases

Covalent immobilizations of bovine liver catalase onto activated florisil, nonporous glass beads (NPG), controlled pore glass beads (CPG) and Eupergit C and Eupergit C 250L were investigated. The immobilization of catalase onto florisil and CPG via spacer arms, 1,4 buthanediol diglycidyl ether (1,4 BDDGE), polyethylene glycol diglycidyl ether (PEGDGE), 5-aminopentanoic acid (5-APA) and 6-amino hexanoic acid (6-AHA), were also investigated. The optimum immobilization conditions (pH, buffer concentration, initial catalase concentration, temperature and immobilization time) and the conditions in which immobilized catalases showed their maximum activities (pH, buffer concentration, temperature) and the kinetic parameters (Km, Vmax, kcat/Km, Ea) were determined for all immobilized catalase preparations. The images of all immobilized catalase preparations were investigated at scanning electron microscope. The thermal stabilities, storage stabilities and usages in plug flow type and batch type reactors of all immobilized catalase preparations were determined.Catalase directly immobilized onto CPG with pore diameter of 70 nm showed the highest catalytic efficiency (kcat/Km) as 1.7x106 s-1M-1 among the others. Among all immobilized catalase preparations, the best three preparations which have the longer half lives (t1/2) than the others were catalase directly immobilized onto florisil (6.2 h), onto CPG (5.2 h) and immobilized catalase onto Eupergit C (4.8 h) at 50ºC, respectively. Immobilized catalase onto CPG and onto Eupergit C showed higher storage stabilities than the other catalase preparations at 5ºC. The highest total productivity (69.7×105 U g immobilized catalase-1) obtained in plug flow reactor was about 11 fold higher than the highest productivity (6.2×105 U g immobilized catalase-1) obtained in batch type reactor when the remaining activity of catalase directly immobilized onto CPG was about 50 % of its original activity.As a result of this study, the most suitable carrier for the catalase immobilization is CPG among all tested carriers; the best preparation is the catalase directly immobilized onto CPG and also the usage of the plug flow type reactor seems to be more suitable for the catalase directly immobilized onto CPG.