Copper(II)ethylenediaminetetraacetate does disproportionate superoxide.

The superoxide dismutase (SOD) mimetic reactivity of Cu(II)EDTA was studied in the pH range of 6.0 to 8.0. Cu(II)EDTA disproportionated superoxide without inhibiting superoxide production by xanthine oxidase, as a result of bonding sites becoming available on the copper complex with increasing acidity. This disproportionation by Cu(II)EDTA is offered as evidence that the addition of EDTA to biological preparations for the purpose of complexing copper and thereby inhibiting copper-dependent superoxide disproportionation and promoting superoxide-dependent reactions is not a valid practice.