Chitosan‐Based metal-organic framework for Stabilization of β-glucosidase: Reusability and storage stability

Enzyme immobilization is a powerful tool for protecting enzymes from harsh reaction conditions and improving enzyme activity, stability, and reusability. In this study, metal organic frameworks (MIL-Fe composites) were synthesized via solvothermal reactions and then modified with chitosan (CS). β-Glucosidase was immobilized on the chitosan-metal organic framework (CS-MIL-Fe), and the resulting composites were characterized with various analytical techniques. The β-glucosidase immobilized on a CS-MIL-Fe composite had an immobilization yield of 85 % and a recovered activity of 74 %. The immobilized enzyme retained 81 % of its initial activity after ten successive cycles and preserved 69 % of its original activity after 30 days of storage at 4 °C. In contrast, the free enzyme had only preserved 32 % of its original activity after 30 days. Under various temperature and pH conditions, the immobilized enzyme showed greater stability than the free enzyme, and the optimal temperature and pH were 60 °C and 6.0 for the immobilized enzyme and 50 °C and 5.0 for the free enzyme. The kinetic parameters were also determined, with the Km values of 13.4 and 6.98 mM for the immobilized and free β-glucosidase, respectively, and Vmax values of 3.96 and 1.72 U/mL, respectively. Overall, these results demonstrate that the CS-MIL-Fe@β-glucosidase is a promising matrix showing high catalytic efficiency and enhanced stability.