Extraction, precipitation and characterization of urease from Vicia faba L.


This study aimed to extract urease enzyme from available plant source which was broad beans (Vicia faba L.) using aqueous solution in a ratio1:3(w:v) .The crude extract appeared enzyme activity 33.3 U/ml. Results of this study revealed the possibility to precipitate urease enzyme after extraction using different precipitation methods consisted of Acetone precipitation; Alcohol precipitation and Ammonium sulfate precipitation, these ways of urease precipitation gave enzyme activities 74.8; 43.6 and 82.2 U/ml respectively .The enzyme precipitation using 60% saturation ratio of Ammonium sulfate gave the maximum activity of urease precipitation among other precipitation methods. Enzyme characterization appeared the optimum pH of urease activity was 8.0 and gave enzyme activity 93.8U/ml, while the optimum pH of urease stability was 6.0; the enzyme maintains its activity. On the other side the optimum temperature of precipitated urease activity was 50°C and the enzyme activity reached 99.3U/ml while the optimal temperature of urease stability was 40°C ,the precipitated urease maintain 100% of activity. The effect of other factors on urease action were studied also, these are consisted of the storage time of enzyme ,urease maintain its activity for 8days and the activity begun to decline after that time; the effect of time reusability was also revealed that the enzyme could be used for six times and maintain its activity. The influence of different mineral salts on precipitated urease were also recorded ;these salts were CuSO4 , MgSO4, MgCl2,KCl,CaCl2and FeSo4, results appeared that magnesium and calcium salts were activator for the precipitated urease while copper ,potassium and ferrous salts were inhibitor of the precipitated urease. Urea concentration as an enzyme substrate were also examined and results appeared the optimal substrate concentration was 30mM; enzyme activity reached to125.2U/ml.