Studies on the mobilization of iron from ferritin by isolated rat liver mitochondria

Rat liver mitochondria and rat liver mitoplasts mobilize iron from ferritin by a mechanism which depends on a respiratory substrate (preferentially succinate), a small molecular weight electron mediator (FMN, phenazine methosulphate or methylene blue) and (near) anaerobic conditions. The release process under optimized conditions (approx. 50 mumol/1 FMN, 1 mmol/l succinate, 0.35 mmol/1 Fe(III) (as ferritin iron), 37 degrees C and pH 7.40) amounts to 0.9--1.2 nmol iron/mg protein per min. The results suggest that ferritin might function as an intermediate in the cytosolic transport of iron to the mitochondria.