title: Release of iron from ferritin by xanthine oxidase. Role of the superoxide radical.
abstract: Mobilization of iron from ferritin by xanthine oxidase was studied under aerobic and anaerobic conditions. Aerobic iron release amounted to approx. 3.7 nmol/ml in 10 min. This amount was decreased by approx. 30% under anaerobic conditions. Aerobic iron mobilization involved two mechanisms. About 70% was released by O2.- generated by xanthine oxidase. The rest was released by O2(.-)-independent mechanisms, which also accounted for the total iron release when O2 was absent. A possible transfer of reducing equivalents directly from xanthine oxidase to ferritin is discussed. The results imply that, in pathological conditions with increased formation of O2.-, iron may be released from ferritin. Furthermore, in hypoxic tissues xanthine oxidase can release iron from ferritin by an O2(.-)-independent process. Free iron is liable to catalyse the formation of the extremely reactive and damaging OH. radical.
mesh_terms: D000693:Anaerobiosis; D005293:Ferritins / Q000378:metabolism*; D005609:Free Radicals; D007501:Iron / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism*
chemical_list: D005609:Free Radicals; D013481:Superoxides; D005293:Ferritins; D007501:Iron; D013482:Superoxide Dismutase; D014969:Xanthine Oxidase; D010100:Oxygen