A Positive Effect of Magnetic Field on the Catalytic Activity of Immobilized L-Asparaginase: Evaluation of its Feasibility

Enzyme immobilization is an attractive strategy to improve enzyme stability, however, the activity significantly reduces after immobilization. To solve this issue, we designed a novel magnetic carrier that both enhanced enzyme activity and improved its stability. For this purpose, the magnetic nanoparticles were synthesized and L-asparaginase was immobilized physically. All materials were structurally and morphologically characterized. Besides, the biochemical properties of the immobilized enzyme were investigated and compared with the free one. Moreover, the activity of the immobilized enzyme was investigated under a weak magnetic field. The optimum pH and optimum temperature of the free and immobilized enzyme were found to be 8.5 and 45 degrees C, 7.5 and 40 degrees C, respectively. Moreover, even after 10 cycles of use, the immobilized enzyme retained 54% of its initial activity. K-m for free and the immobilized enzyme was found to be 10.37 +/- 0.5, and 7.06 +/- 2.99 mM, respectively, and V-max was found to be 138.88 +/- 2.64, and 121.95 +/- 1.07 molimin, respectively. Most importantly, the activity increased approximately 3.2-fold and 4.3-fold at 10 Hz and 20 mT, respectively. Overall, the results suggested that, if the activity of the immobilized enzyme is very low, applying a weak magnetic field may be necessary to enhance the enzyme reaction. [GRAPHICS] .