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 (By similarity). 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 110 Fe(3+) can be deposited. The N-terminus is blocked. The dps dodecamer comprises iron-binding sites for iron translocation, oxidation and nucleation. Fe(2+) atoms are initially bound to the outer surface in proximity to the iron entry pore from which they are translocated toward the inter-subunit ferroxidase centers via two discrete steps. Iron oxidation proceeds by transient formation of tri-iron ferroxidase centers and Fe(3+) atoms move to two distinct iron nucleation centers where iron mineralization occurs. Belongs to the Dps family.