Involved in the detoxification of arsenic. Oxidizes As(III)O3(3-) (arsenite) to the somewhat less toxic As(V)O4(3-) (arsenate). arsenite + H2O + 2 oxidized [azurin] = arsenate + 3 H(+) + 2 reduced [azurin] Binds 1 [2Fe-2S] cluster per subunit. Heterodimer consisting of a large and a small subunit. Induced in the presence of arsenite. Predicted to be exported by the Tat system. The position of the signal peptide cleavage has not been experimentally proven. Belongs to the AOX family.