Urease was immobilized on chitosan with glutaraldehyde as the crosslinking reagent.The optimum conditions of immobilization for the enzyme were that chitosan was crosslinked with 6% glutaraldehyde in the enzyme solution of pH7.0 and reacted with urease for 1.5h.The study on the enzymatic characterizations of free and immobilized urease indicated that optimum pH value of the enzymatic reaction was 7.0,the optimum temperatures were 28℃ and 68℃ respectively.The Km value for urea were 16mmol/L and 5 mmol/L respectively.Keeping the free and immobilized urease at 25℃ for 120min,the activity remained 35% and 72% respectively.It indicated that the immobilized enzyme had better thermal stability.
