Immobilization of enzymes on magnetic carriers: Optimization of immobilization conditions for chicken intestine alkaline phosphatase

Chicken intestine alkaline phosphatase was immobilized on seven carriers by adsorption or covalent binding. The efficiency of immobilization depended on the carrier, immobilization method, and initial enzyme concentration. The heat stability of the soluble and immobilized enzyme preparations, and the dependence of the enzyme activity on pH and Zn2+ and Mg2+ ions were studied. Alkaline phosphatase immobilized on magnetic carriers displayed a lower heat stability than the soluble enzyme. The temperature optima of the immobilized and soluble enzymes were 80 and 60 degrees C; the pH optima were 9.0 and 8.0, respectively. Ions Mg2+ and Zn2+ were found to play an important role in the activation of both soluble and immobilized enzymes and their stabilization at high temperatures.