IMMOBILIZATION OF UREASE ON VERMICULITE

Urease (EC 3.5.1.5) of high activity was obtained 2.2 when the enzyme was immobilized on vermiculite crosslinked with 2.5% glutaraldehyde in chilled EDTA-phosphate buffer (pH 5.5). The highest activity of the i mmobilized enzyme was at 65 degrees C and PH 6.5 while the optimum tem perature for free urease was found to be 25 degrees C. The thermal sta bility of immobilized urease was observed to be much better than that of the free urease. When stored at 4 degrees C, urease immobilized on vermiculite retained 69 to 81% of its activity after 60 days and 61 to 75% of its original activity was retained after 4 repeated uses.