摘要 : Release of iron from ferritin requires reduction of ferric to ferrous iron. The iron can participate in the diabetogenic action of alloxan. We investigated the ability of ascorbate to catalyze the release of iron from ferritin in ... 展开 Release of iron from ferritin requires reduction of ferric to ferrous iron. The iron can participate in the diabetogenic action of alloxan. We investigated the ability of ascorbate to catalyze the release of iron from ferritin in the presence of alloxan. Incubation of ferritin with ascorbate alone elicited iron release (33 nmol/10 min) and the generation of ascorbate free radical, suggesting a direct role for ascorbate in iron reduction. Iron release by ascorbate significantly increased in the presence of alloxan, but alloxan alone was unable to release measurable amounts of iron from ferritin. Superoxide dismutase significantly inhibited ascorbate-mediated iron release in the presence of alloxan, whereas catalase did not. The amount of alloxan radical (A center dot(-)) generated in reaction systems containing both ascorbate and alloxan decreased significantly upon addition of ferritin, suggesting that A center dot(-) is directly involved in iron reduction. Although release of iron from ferritin and generation of A center dot(-) were also observed in reactions containing GSH and alloxan, the amount of iron released in these reactions was not totally dependent on the amount of A center dot(-) present, suggesting that other reductants in addition to A center dot(-) (such as dialuric acid) may be involved in iron release mediated by GSH and alloxan. These results suggest that A center dot(-) is the main reductant involved in ascorbate-mediated iron release from ferritin in the presence of alloxan and that both dialuric acid and A center dot(-) contribute to GSH/alloxan-mediated iron release. 收起