title: Mechanism of ascorbic acid regeneration mediated by cytochrome b561.
abstract: In summary, ascorbic acid serves as a one-electron donor for dopamine beta-hydroxylase in chromaffin vesicles and probably for peptide amidating monooxygenase in neurohypophyseal secretory vesicles. It appears that the semidehydroascorbate that is produced is reduced by cytochrome b561 to regenerate intravesicular ascorbate. Cytochrome b561, a transmembrane protein, is reduced in turn by an extravesicular electron donor, probably cytosolic ascorbic acid. It will be interesting to see whether other ascorbate-requiring enzymes in other organelles use a similar ascorbate-regenerating system to provide an intravesicular supply of reducing equivalents.
authors.forename: D
authors.initials: D
authors.lastname: Njus
authors.forename: P M
authors.initials: PM
authors.lastname: Kelley
authors.forename: G J
authors.initials: GJ
authors.lastname: Harnadek
authors.forename: Y V
authors.initials: YV
authors.lastname: Pacquing
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D002837:Chromaffin Granules / Q000378:metabolism*; D002838:Chromaffin System / Q000378:metabolism*; D003573:Cytochrome b Group / Q000378:metabolism*; D003683:Dehydroascorbic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D004299:Dopamine beta-Hydroxylase / Q000378:metabolism*; D004579:Electron Transport; D005609:Free Radicals
chemical_list: D003573:Cytochrome b Group; D005609:Free Radicals; C023646:cytochrome b561; C000820:semidehydroascorbic acid; D004299:Dopamine beta-Hydroxylase; D001205:Ascorbic Acid; D003683:Dehydroascorbic Acid