Protects DNA from oxidative damage by sequestering intracellular Fe(2+) ion and storing it in the form of Fe(3+) oxyhydroxide mineral. One hydrogen peroxide oxidizes two Fe(2+) ions, which prevents hydroxyl radical production by the Fenton reaction (Probable). Does not bind DNA. 2 Fe(2+) + 2 H(+) + H2O2 = 2 Fe(3+) + 2 H2O Homododecamer. The 12 subunits form a hollow sphere into which the mineral iron core of up to 500 Fe(3+) can be deposited (By similarity). Constitutively expressed. Not induced by hydrogen peroxide or by iron. Belongs to the Dps family.