Ascorbic acid, metal ions and the superoxide radical.
1. No evidence could be found for production of the superoxide radical, O2-, during autoxidation of ascorbic acid at alkaline pH values. Indeed, ascorbate may be important in protection against O2- genat-d in vivo. 2. Oxidation of ascorbate at pH 10.2 was stimulated by metal ions. Stimulation by Fe2+ was abolished by superoxide dismutase, probably because of generation of O2-- during reduction of O2 by Fe2+, followed by reaction of O2-- with ascorbate. EDTA changed the mechanism of Fe2+-stimulated ascorbate oxidation. 3. Stimulation of ascorbate oxidation by Cu2+ was also decreased by superoxide dismutase, but this appears to be an artifact, since apoenzyme or bovine serum albumin showed similar effects.
D001205:Ascorbic Acid; D004492:Edetic Acid; D004837:Epinephrine; D007501:Iron; D010084:Oxidation-Reduction; D010100:Oxygen; D012710:Serum Albumin, Bovine; D013482:Superoxide Dismutase; D013481:Superoxides; D015032:Zinc
D013481:Superoxides; D012710:Serum Albumin, Bovine; D004492:Edetic Acid; D007501:Iron; D013482:Superoxide Dismutase; D015032:Zinc; D001205:Ascorbic Acid; D010100:Oxygen; D004837:Epinephrine