DECAY OF SUPEROXIDE CATALYZED BY FERRITIN

Ferritin iron can be reduced by O2.-, 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 O2.-, monitored by direct spectrophotometry at pH 9.5. Ferritin, but not apoferritin, accelerated the decay of O2.-. Ferritin iron was apparently the responsible agent. The effect of ferritin was maintained after several bursts of O2.-, and the ratio degraded O2.-/released Fe(II) greatly exceeded one, consistent with a catalytic reaction.