title: Iron uptake and heme synthesis by isolated rat liver mitochondria. Diferric transferrin as iron donor and the effect of pyrophosphate.
abstract: Isolated rat liver mitochondria accumulate iron from fully saturated transferrin at neutral pH. With 5 microM iron as diferric transferrin, accumulation at 30 degrees C amounts to approx. 40 pmol/mg protein per h. With access to a suitable porphyrin substrate, 70-80% of the amount of iron accumulated is recovered in heme. Mobilization of iron and synthesis of heme both depend on a functioning respiratory chain. Vacant iron-binding sites on mono- and apotransferrin compete with the mitochondria for iron mobilized from transferrin. Pyrophosphate at concentrations in the range 10-50 microM enhances mobilization of iron, counterbalances the inhibitory effect of mono- and apotransferrin and enhances metallochelatase activity. The results emphasize the putative suitability of pyrophosphate as an intracellular iron-transport ligand in situ.
mesh_terms: D000818:Animals; D000968:Antimycin A / Q000031:analogs & derivatives / Q000494:pharmacology; D003486:Cyanides / Q000494:pharmacology; D011756:Diphosphates / Q000494:pharmacology*; D006418:Heme / Q000096:biosynthesis*; D007457:Iodine Radioisotopes; D007501:Iron / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008930:Mitochondria, Liver / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D014168:Transferrin / Q000378:metabolism*
chemical_list: D003486:Cyanides; D011756:Diphosphates; D007457:Iodine Radioisotopes; D014168:Transferrin; C032456:antimycin; D006418:Heme; D000968:Antimycin A; D007501:Iron