Iron transfer form transferrin to ferritin mediated by polyphosphate compounds.

We have studied iron transfer from transferrin to ferritin in the presence of ATP, GTP, ADP, AMP and 2,3-diphosphoglycerate. These compounds, with the exception of AMP, can release iron from transferrin at pH 7.4 and form a stable Fe(III)-phosphate complex. From these complexes, only a limited number of Fe(III) atoms can be incorporated into ferritin. Ascorbate enhances iron transfer from transferrin to ferritin at the beginning of the process but subsequently inhibits further iron deposition in ferritin.