Interaction of horse-spleen ferritin with aluminium citrate

Horse-spleen ferritin was found to bind Al systematically following gel filtration in buffered Al citrate 30 microM, and up to molar ratio 98 when incubated at 37 degrees C with Al citrate, buffered to pH 7.4. Pre-incubation with 3 concentrations of neutral sodium phosphate (0.1, 1.0, 10.0 mM) had no significant effect on binding. Apotransferrin interaction with the Al-ferritin complex to release Fe but not Al. Protein-digestion and EDTA washing procedures showed that the Al was firmly bound to the ferritin, probably to the core. Since ferritin species from different organs are relatively alike, we suggest that in the gut ferritin may scavenge Al followed by its re-excretion into the lumen with the mucosal cells, thus protecting against absorption of the metal.