Free radical in vitro inactivation of glucose-6-phosphate dehydrogenase from the yeast Saccharomyces cerevisiae
Partial purification and in vitro inactivation of glucose-6-phosphate dehydrogenase from the yeast Saccharomyces cerevisiae in the Fe2+/Н2О2 oxidation system were conducted. At the protein concentration 1.5 mg/ml, the enzyme lost 50% of activity within 5 minutes of incubation in presence of 2 mM hydrogen peroxide and 3 mM ferrous sulphate. The inactivation extent depended on time and concentrations of FeSO4 and Н2О2.EDTA, АDP and АТP at concentration 0.5 mM enhanced inactivation. At the same time, the presence of 0.5 mM NADPH, 1 mM glucose-6-phosphate, 10 mM mannitol, 30 mM dimethylsulphoxide or 20 mM urea diminished this process. In comparison with native enzyme, index S0,5 of the partially inactivated enzyme for glucose-6-phosphate was 2.1-fold higher, but for NADP it was 1.6-fold lower. Maximal activity of the partially inactivated enzyme was 3-5-fold lower than that of native one.
Published at the site: 2005-02-02
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