Urease (Urea amidohydrolase; EC 3.5.1.5) was the first enzyme to be crystallized. Urease is an important enzyme present in many organisms, including plants. This enzyme plays diverse roles and mainly involved in the nitrogen metabolism. The bacterial urease has been extensively studied may be due to the simplicity of system and its significance in various pathological conditions and role in agriculture etc. Jack bean urease was the first nickel-containing enzyme to be described and it is the

more »

... y nickel-containing metalloenzyme identified so far in plants. Its rapid catalysis for the hydrolysis of urea to ammonia and carbon dioxide plays an essential role in agriculture and human health. In most of the industrial, analytical, and clinical processes, enzymes are mixed in a solution with substrates and cannot be economically recovered after the exhaustion of the substrates. By mimicking the natural mode of occurrence in living cells, where enzymes for the most cases are attached to cellular membranes, the systems stabilize the structure of enzymes, hence their activities. Thus, as compared to free enzymes in solution immobilized enzymes are more robust and more resistant to environmental changes. More importantly, the heterogeneity of the immobilized enzyme systems allows easy recovery of enzyme and product, multiple reuses of enzymes, continuous operation of enzymatic processes, rapid termination of reactions and greater variety of bioreactor designs.