MOSSBAUER STUDIES OF IRON INCORPORATION INTO FERRITINS

Iron(III) monomers, dimers and clusters have been identified by Mossba uer spectroscopy during the initial stages of iron incorporation into ferritins, following Fr(II) oxidation. Iron(III) monomers stem to aris e from dimer dissociation. Some of the monomers are transferred from i ron poor to iron rich ferritin molecules, where they join the iron cor e clusters. Horse spleen ferritin, several variants of human H chain f erritin and Escherichia coli ferritin (Ec-FTN) can all accept the iron from human H chain ferritin. The small iron cores of Ec-FTN are diffe rent from those of mammalian ferritins, which indicates that the struc ture of the iron core depends on the protein shell.