Preparation and Characterization of κ‐Carrageenan Immobilized Urease

Abstract

Urease was encapsulated within κ‐carrageenan beads. Various parameters, such as amount of κ‐carrageenan and enzyme activity, were optimized for the immobilization of urease. Immobilized urease was thoroughly characterized for pH, temperature, and storage stabilities and these properties were compared with the free enzyme. The free urease activity quickly decreased and the half time of the activity decay was about 3 days at 4°C. The immobilized urease remained very active over a long period of time and this enzyme lost about 70.43% of its orginal activity over the period of 26 days for storage at 4°C. The Michaelis constant (K_m) and maximum reaction velocity (V_max) were calculated from Lineweaver‐Burk plots for both free and immobilized enzyme systems. V_max = 227.3 U/mg protein, K_m = 65.6 mM for free urease and V_max = 153.9 U/mg protein, K_m = 96.42 mM for immobilized urease showed a moderate decrease of enzyme specific activity and change of substrate affinity.

Keywords:

• Urease
• κ‐Carrageenan
• Urease immobilization
• Urea removal