Cu-trimesic acid-based metal organic frameworks for improved ß-galactosidase immobilization: Enhanced stability, reusability and lactose hydrolysis

The immobilization of beta-galactosidase on Cu-trimesic acid-based metal organic frameworks (Cu-TMAs) was studied. The results showed that the immobilization yield was 79 %, and the activity yield was 86 %, indicating that a significant amount of the enzyme activity was retained after immobilization. The morphological structures of Cu-TMA and beta-galactosidase@Cu-TMA were studied with SEM, and the chemical changes in Cu-TMA after immobilization were monitored with FTIR spectroscopy. The immobilized enzyme retained 83 % of its activity after it was used for six consecutive batches and showed good storage stability, retaining 78 % of its initial activity after it was stored at 4 degrees C for two months. Additionally, the optimum pH for the immobilized beta-galactosidase was shifted to pH 7.0, and the optimal temperature was 60 degrees C, 10 degrees C higher than that of the free enzyme. The immobilized enzyme demonstrated better lactose hydrolysis activity than the free enzyme; it exhibited 83 % hydrolysis after 4 h at 60 degrees C and continued to hydrolyse the lactose, and 85 % hydrolysis was achieved after 5 h. Overall, this study demonstrated the potential of Cu-trimesic acid-based metal organic frameworks as supports for immobilizing beta-galactosidase. The results of this study suggest that the immobilized enzyme may have practical applications in various industrial processes.