Immobilization of Citrullus vulgaris urease on cyanuric chloride deae-cellulose ether: Preparation and properties

C. vulgaris urease was successfully immobilized on cyanuric chloride DEAE-cellulose ether with a 72% retention of activity. The properties of free and immobilized urease were compared. Both free and immobilized enzymes exhibited pH optima values at 7.5. The Michaelis constant was about 3.8 times higher for immobilized urease than for the free enzyme. The free urease had an optimum temperature at 55°C, while it shifted to 65°C for the immobilized enzyme. The activation energy for the free and immobilized enzymes was found to be 7.1 and 7.7 kcal mol−1, respectively. Temperature stability was also improved. While the immobilized urease retained 18% of its activity after 15 min at 90°C, a complete loss of the free enzyme activity was recorded. The stability and toxicity sequence of C. vulgaris urease against metal ions inactivation was considerably improved after immobilization. The immobilized enzyme had good storage, stability and reusability, properties that offer potential for practical application.