A third iron site in EcFtna

In RNR R2 it is thought that, along with the dinuclear Fe(II) pair and the formation of a tyrosyl radical, a third Fe(II) is oxidized by dioxygen enabling its reduction to water (see Chapter 16) [48]. This third Fe(II) may be in solution or at a third site on the protein of unknown position. In EcFtna the known third Fe site (C) is located on the inside surface of the protein shell at ca 6 A from the dinuclear center 

6 Formation of blue or purple spedes as early oxidation products 

A similar blue complex (A ax = 650 nm) has also been observed in recombinant frog M subunit ferritin (FrMF) and it is both spectroscopically distinct from and 

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