Chelate mediated transfer of iron from transferrin to desferrioxamine

Desferrioxamine, widely used for the treatment of iron overload in Cooley's anaemia, binds iron so tightly that it should quantitatively remove iron from transferrin. Studies conducted in vivo and in vitro, however, have failed to demonstrate significant depletion of transferrin-bound iron by a stoichiometric excess of desferrioxamine. However, low molecular weight chelating agents, capable of forming ternary complexes with transferrin and ferric iron, can promote a rapid transfer of iron from transferrin to desferrioxamine. A possible mechanism for this facilitated exchange is offered.