Immobilization and characterization of cellulase enzyme on epoxy metacrylate and epoxy butyl metacrylate by covalent binding method

In recent years, immobilization studies with nanopolymeric materials have become widespread. The surface properties of these nanopolymeric materials are the most important factors in which method of immobilization is performed. In this study, the covalent immobilization of cellulase enzyme obtained from aspergillus strain with epoxy methacrylate and epoxy butyl methacrylate polymers was investigated. In addition, thermal and storage stability of free and immobilized cellulases and re-use stability of immobilized cellulases were investigated. The activity measurements of free and immobilized enzymes were measured and the reusability of immobilized cellulases with optimum temperature, optimum pH, thermal and storage stability and kinetic parameters were determined. The optimum pH for free cellulase was 5.5, the optimum temperature was 60⁰C, for the immobilized enzymes the optimum pH was 6.5 and the optimum temperature was 50⁰C. The thermal stability of the free and immobilized cellulases was determined by standing at a certain temperature for a period of time and it was observed that the immobilized enzymes were more resistant than the free enzyme. Storage stability of free and immobilized enzymes at 5⁰C and 25⁰C were observed for 35 days. It was observed that the activity of free cellulase which was kept at 5ºC on the 15th day was 4.07% and the free cellulase, which was kept at 25⁰C, was denatured after 3 days and did not show any activity. The enzyme immobilized with epoxy methacrylate is retained 37.5% of its activity at day 30 at 5⁰C, 22.5% at day 25 at 25⁰C and did not show activity at day 30. The enzyme immobilized with epoxy butyl methacrylate is maintained 44.7% of its activity at 5⁰C 30th day, 32% at 25⁰C at 25⁰C, and showed an activity of approximately 6% at 30th day. Km and Vmax values under the optimum conditions determined for free cellulase Km 0,626 mg/mL, Vmax 0,964 U/g ; for immobilized cellulases, Km 1,703 mg/mL (EMA), 4,454 mg/mL (EBMA), Vmax 4,019 U/g (EMA), 0,507 U/g (EBMA) respectively.