Iron(III) species formed during iron(II) oxidation and iron-core formation in the bacterioferritin of Escherichia coli

Summary This paper describes a preliminary investigation of the mechanisms of Fe(II) oxidation and storage of Fe(III) in the bacterioferritin ofEscherichia coli (EcBFR). Using M?ssbauer spectroscopy to examine the initial oxidation of iron by EcBFR we have confirmed that this ferritin exhibits ?ferroxidase? activity and have shown that dimeric and monomeric iron species are produced as intermediates. We compare the characteristics of ferroxidase activity in EcBFR with those of human H-chain ferritin (HuHF) and discuss the different M?ssbauer parameters of their dimeric iron with reference to the structures of their di-metal sites. In addition, we present preliminary findings suggesting that after an initial ?burst?, the rate of oxidation is greatly reduced, possibly due to blockage of the ferroxidase centre by bound iron. A new component, not found in HuHF and probably representing a small cluster of Fe(III) atoms, is reported. Paper presented at the ICAME-95, Rimini, 10–16 September 1995.