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Some Biochemical Properties of Catalase from Kohlrabi (Brassica oleracea gongylodes)

Author(s): Hossein Tayefi-Nasrabadi

Journal: Journal of Biological Sciences
ISSN 1727-3048

Volume: 8;
Issue: 3;
Start page: 649;
Date: 2008;
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Keywords: Kohlrabi | catalase | inhibitor | isoenzyme | thermostability

The purpose of this research was to investigate and characterize catalase activity in kohlrabi bulbs. Catalase (EC was extracted from kohlrabi bulbs with 0.05 M phosphate buffer, pH 7.0. On the basis of kinetic studies and activity staining for catalase on non-denaturant polyacrylamide gel electrophoresis, only three isoenzymes of catalase were detected in kohlrabi bulbs extract with pH optima at 4.5, 6.5 and 10. Their apparent molecular weights were 308,000, 285,000 and 258,000. Data for Vmax/Km values, which represent catalytic efficiency, show that isoenzyme active at pH 6.5 has the highest value. Isoenzyme active at pH 4.5 was very sensitive to azide and more resistant to cyanide in comparison to other two isoenzymes active in kohlrabi bulbs extract. Up to 38 mM H2O2 concentration, substrate inhibition was found only for the isoenzyme active at pH 4.5. The order of thermostability of three catalase isoenzymes from kohlrabi bulbs extract at three pH optima was pH 4.5>10>6.5.
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