Further characterization of the two catalases inEscherichia coli |
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Authors: | Efrat Meir Dr. Ezra Yagil |
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Affiliation: | (1) Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, 69978 Tel Aviv, Israel |
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Abstract: | Crude extracts of wild-typeEscherichia coli contain two catalase species that separate on native polyacrylamide gels. The slow-migrating enzyme (HPII) has two pH optima of activity (at pH 6.8 and 10.5), is activated at 70°C, is sensitive to inhibitory by 3-amino-1,2,4-triazole and has Km values of 18.2 mM at pH 6.8 and of 10 mM at pH 10.5. The fast-migrating enzyme has a single pH optimum of 6.8 and is composed of two isozymes (HPI-A and HPI-B). Its activity is labile at 70°C, it is relatively resistant to inhibition by 3-amino-1,2,4-triazole and has a Km value of 3.7 mM. |
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