The superoxide-dependent transfer of iron from ferritin to transferrin and lactoferrin.

By the use of gel filtration and [59Fe]ferritin, apotransferrin and apolactoferrin were shown to take up iron released from ferritin by superoxide generated by hypoxanthine and xanthine oxidase. Apotransferrin also inhibited uptake of released iron by ferrozine. Ferritin and the xanthine oxidase system induced lipid peroxidation in phospholipid liposomes. This peroxidation was inhibited by apotransferrin or apolactoferrin. Thus, although superoxide and other free radicals can release iron from ferritin, either iron-binding protein, if present, should take up this iron and prevent its catalysing subsequent oxidative reactions.