Pigeonpea (Cajanus cajan) urease immobilized on alginate beads showing improved stability and operational parameters
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Date
2013
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Sardar Vallabhbhi Patel Universiy of Agriculture And Technology Meerut (U.P.)
Abstract
Plant urease (urea amidohydrolase; EC 3.5.1.5) is a seed protein that is common in most legumes. It is also common in many bacteria and fungi and several species of yeast. Urease allows organisms to use exogenous and internally generated urea as a nitrogen source by catalyzing the hydrolysis of urea to ammonia and carbon dioxide. Urease from pigeonpea (Cajanus cajan) was immobilized in alginate beads by entrapment method. Approximately 48% immobilization of urease in alginate was observed at 3.5% (w/v) alginate with 0.65 mg protein/5 ml alginate gel. From steady state kinetics, the optimum temperature for soluble urease was 65 oC and 80 oC for immobilized urease, the optimum pH of urease 7.3 (soluble) and 8.0 (alginate immobilized). It was observed that there was a increase in Km for alginate-immobilized urease (4.34 mM) when compared with soluble urease (3.30 mM).The alginate immobilized ureases showed a decrease in Vmax (0..769 µmol NH3 min-1 mg-1 protein) as compare to soluble enzymes (0.80 µmol NH3 min-1 mg-1protein).With time-dependent thermal inactivation studies. The immobilized enzyme showed improved stability at 75 oC and the t1/2 of decay in urease activity was 12 min and 50 min for soluble and immobilized urease, respectively. The reusability studies revealed that the alginate immobilized urease after 8 uses retained more than 50% of the original activity. The immobilized urease was always kept in 50 mM Tris-acetate buffers, pH 7.3 at 4 oC. For storage stability studies, the loss of activity, for soluble urease after 50 days of storage at 4 oC was 80% and in comparison to alginate immobilized urease the loss was 51%. The plot of % residual activity versus the number of days gave a t1/2 of 30 days for soluble urease; 51 days for alginate-immobilized urease.
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Pigeonpea (Cajanus cajan) urease immobilized on alginate beads showing improved stability and operational parameters
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Pigeonpea (Cajanus cajan) urease immobilized on alginate beads showing improved stability and operational parameters