Enzymatic recycling of oxidized ascorbate in pig heart: one-electron vs two-electron pathway.
Enzymatic systems able to reduce either dehydroascorbate or ascorbyl radical back to ascorbate by "recycling" vitamin C may contribute to lowering the nutritional requirement of it and to increase tissue antioxidant capacity. The activities of two enzymatic activities, GSH-dehydroascorbate reductase (two-electron reduction pathway) and NADH-semidehydroascorbate reductase (one-electron reduction pathway) in pig tissues, have been investigated. The activity of glutathione-dependent reduction of dehydroascorbate, although measurable, appeared negligible taking into consideration the low physiological substrate concentration. On the other hand, the one-electron reduction of ascorbyl radical resulted fast enough to slow down the consumption of the antioxidant vitamin.
Department of Biological Chemistry, University of Padova, Italy.
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Coassin
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Tomasi
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Vannini
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Ursini
D000818:Animals; D003683:Dehydroascorbic Acid / Q000378:metabolism*; D004579:Electron Transport; D005609:Free Radicals; D009206:Myocardium / Q000201:enzymology*; D009928:Organ Specificity; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism*; D010940:Plant Proteins / Q000737:chemistry; D012995:Solubility; D013552:Swine; D014018:Tissue Distribution
D005609:Free Radicals; D010940:Plant Proteins; D010088:Oxidoreductases; C020666:glutathione dehydrogenase (ascorbate); D003683:Dehydroascorbic Acid