Immobilization of l-asparaginase used for cancer treatment to magnetic nanoparticles

In this thesis, anti-leukemic enzyme L-asparaginase (E.C. 3.5.1.1.) from E. coli was immobilized on the magnetic poly(HEMA-GMA) nanoparticles. Characterization studies revealed that, the average size of the magnetic nanoparticles was 117.5 nm and asparaginase was covalently immobilized to the synthesized magnetic nanoparticles. Immobilized enzyme was calculated to be 66.43 mg asparaginase/g nanoparticles. The effects of pH, temperature and substrate concentration on the activity of the immobilized asparaginase were investigated. Optimum pH of free asparaginase was found to be 7.5, while optimum pH of the immobilized asparaginase was found to be 6.5. Optimum temperature of the immobilized asparaginase increased 10 °C, and was observed to be 55°C. kcat value of free asparaginase (47356 dak-1) was found to be higher than that of immobilized asparaginase (497 dak-1). Additionally, thermal and storage stabilities of free and immobilized asparaginase were investigated, and operational stability of immobilized asparaginase was determined. In this presented thesis, in order to detect the efficiency of the immobilized asparaginase in artificial human serum, activities of free and immobilized asparaginase were measured, and it was observed that, immobilized asparaginase carried 74.74 % of its initial activity. These results showed that, asparaginase immobilization process in this work was successful.