مرکز منطقه ای اطلاع رساني علوم و فناوري - تنقية و توصيف انزيم Asparaginase من Proteus vulgaris

Other languages abstract :

The enzyme was extracted from Proteus vulgaris and partially purified by many steps including precipitation with ammonium sulfate by using different saturation percentages; the optimum percent was 80% gave value of specific activity 0.86 U/mg protien. then ion exchange chromatography by DEAE-cellulose column, the specific activity 2.7 U/mg protien, and gel filtration using Sephadex G-200 column specific activity 6U/mg protein. Characterization showed that the optimum pH and temperature for enzyme activity 7.5,37ْC respectively, and the optimum pH for enzyme stability between 7.5-8.5and the value of activation energy for conversion substrate to product 6825 Cal/mole. The enzyme stable between 20-37ْC. the enzyme has an absolute specificity toward Asparagine. The kinetic constants were determined, Km 2.85×10³‾M and Vmax 0.25×10³‾ M/min when Asparagine was used as a substrate. The effect of (some inorganic salts, chelating and reducing agent) on enzyme activity, the results showed that non sodium chloride and potassium chloride affect significantly the activity. the enzyme appear to be resistant to calcium chloride and magnesium chloride and keep full enzyme activity in the presence of EDTA and FeSO4, the results showed that the activity of enzyme lost 16,13% respectively in the presence of Cystien and 2-mercaptoethanol at 10 mM while chloride of Copper had complete inhibitory effect of enzyme activity.