Decay of Superoxide catalyzed by ferritin

Abstract

Ferritin iron can be reduced by O^.− ₂, released, and form a Fe(II)-chelator complex. However, the thermodynamic influence of the chelator may disturb the reaction balance. We therefore excluded the chelator and measured instead the effect of ferritin on the decay of O^.− ₂, monitored by direct spectrophotometry at pH 9.5. Ferritin, but not apoferritin, accelerated the decay of O⁻ ₂. Ferritin iron was apparently the responsible agent. The effect of ferritin was maintained after several bursts of O^.− ₂, and the ratio degraded O^.− ₂/released Fe(II) greatly exceeded one, consistent with a catalytic reaction.