PURIFICATION AND CHARACTERIZATION OF MARINE BACILLUS THURINGIENSIS N2 UREASE

Urease was purified to homogeneity from Bacillus thuringiensis N2 using different purification steps namely, 55% acetone precipitation, DEAE-Sephadex A50 anion exchange column and Sephadex G120-200 gel filtration chromatography. The enzyme was purified 95.27 fold and showed a final specific activity of 10.48 U/mg proteins with a yield 56%. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS/PAGE) of the purified enzyme revealed a single protein band of 97.4 KDa molecular weight. The enzyme showed thermal stability at 50°C and has maximum activity at 25°C, pH 8 and incubation period of 15 min.. A lineweaver- aBurk analysis gave a Km of 2.94 mM and Vmax of 25 µmol/ml/min. The urease activity was enhanced by addition of CuCfe. The enzyme proved to be rich in cysteine, methionine and tryptophan while it contained low amounts of glycine, alanine, and β-alanine.