Rafidain Journal of Science

Abstract

The research was concerned with the isolation of urease form local Vica faba using different biochemical techniques.
It was shown that gel filtration chromatography of the proteinous precipitate which was produced by acetone, heat treatment and acid precipitation gave three proteinous peaks. The first and the second peaks possessed a variable activity of urease where maximum specific activity was obtained in the second peak which showed (40.1) folds of purification.
Furthermore, the comparative molecular weight of the partially purified urease using both sodium dodecyl sulphate-polyacrylamide gel electrophoresis and gel filtration chromatography techniques was found to be (460000 ± 5000)and (480000 ± 8000) dalton respectively .
The optimum conditions of urease was obtained using (50 mM) sodium phosphate buffer at pH (8.3) with incubation temperature (50)ْ C, incubation time (30) minutes and (5 mM) of urea as a substrate. Using Lineweaver-Burk plot, it was found that Vmax and Km had the values of (0.8) unit/ml and (6.06 mM) respectively.
The results were also indicated that the activity of the enzyme decreased gradually to (70%) and (59%) when the enzyme was stored for (30) days at (4)ْC and room temperature respectively. The activity of the enzyme was inhibited by CuCl2 or methyl urea where the inhibition is competitive .
Finally, the results predicted that there was no significant differences between the activity of urease extracted from local Vicia faba and the urease used in the standard kit for the determination of urea in blood for normal and patients.