| Autor: |
Mendonça MH; Departamento de Bioquímica, Universidade Federal do Paraná, Curitiba, PR, Brazil., Zancan GT |
| Jazyk: |
angličtina |
| Zdroj: |
Archives of biochemistry and biophysics [Arch Biochem Biophys] 1989 Nov 15; Vol. 275 (1), pp. 130-9. |
| DOI: |
10.1016/0003-9861(89)90357-3 |
| Abstrakt: |
The effect of ethanol and tunicamycin on synthesis and secretion of galactose oxidase was studied in resting cells of Dactylium dendroides. Ethanol promoted an overall decrease in both intra- and extracellular enzyme levels to the same extent that it inhibited [14C]glucosamine incorporation into total protein. The carbohydrate content of the intracellular enzyme was also depressed (44%) with a simultaneous decrease in O-Ser linked oligosaccharides. The intracellular galactose oxidase obtained after exposure of mycelia to ethanol plus tunicamycin lost 86% of its carbohydrate moieties, whereas the extracellular form lost only 35%. In both cases, residual sugar moieties were not eliminated by mild alkaline treatment. These data suggest that ethanol affects O-glycosylation of galactose oxidase. O-Underglycosylation did not affect the S0.5 values for galactose but diminished the molar catalytic activity. The absence of O-Ser/Thr-linked saccharides turned the intracellular enzyme into a form more susceptible to proteolysis than that devoid of N-linked sugars (tunicamycin-treated). O-Underglycosylation had a significant effect on the renaturation-reactivation of the enzyme after denaturation with 2.4 M Gdn-HCl. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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