Immobilization of catalase via adsorption onto metal-chelated affinity cryogels

A poly (acrylamide-allylglycidyl ether) [p(AAm-AGE)] cryogel was prepared by radical polymerization of acrylamide (AAm) and allylglycidyl ether (AGE). Cibacron Blue F3GA (CB) was covalently attached to the p(AAm-AGE) cryogel via the reaction between the chloride groups of the reactive dyes and the epoxide groups of the AGE. The CB-attached p(AAm-AGE) cryogel was chelated with Fe3+ ions. This immobilized metal ion affinity chromatography (IMAC) cryogel carrying 25.8 ± 2.0 μmol Fe3+ ions was used in adsorption studies to interrogate the effects of pH, protein initial concentration, flow rate, temperature and ionic strength on enzyme activity. Maximum adsorption capacities were found to be 75.7 ± 1.2 mg/g for p(AAm-AGE)–CB–Fe3+ cryogels and 60.6 ± 1.0 mg/g for p(AAm-AGE)–CB cryogels, respectively. The adsorbed amounts of catalase per unit mass of cryogel reached a plateau value at about 1.5 mg/mL at pH 6.0. The Km values were found to be 0.73 ± 0.02 g/L for the free catalase and 0.18 ± 0.02 g/L for the immobilized catalase. The Vmax value of free catalase (2.0 × 103 U/mg enzyme) was found to be lower than that of the immobilized catalase (2.5 × 103 U/mg enzyme). It was also observed that the enzyme could be repeatedly adsorbed and desorbed onto the p(AAm-AGE)–CB–Fe3+ cryogel.

► A novel adsorbent for the metal-chelated affinity immobilization of catalase was produced in this study.
► Incorporation of Fe3+ ions increased the adsorption capacity of the cryogel at about 1.2-fold. Approximately a 4-fold decrease in the Km value for the immobilized catalase was observed.
► The pH and temperature profiles of the immobilized catalase were much broader than that of the free enzyme.
► The enzyme could be repeatedly adsorbed and desorbed onto the p(AAm-AGE)–CB–Fe3+ cryogel.