NAD(P)H:ferric iron reductase in endosomal membranes from rat liver.
Endosomes isolated from rat liver, characterized by high enrichment of endocytosed ligand after liver perfusion, displayed ferric reductase activity with higher affinity for NADH (1.7 microM) than for NADPH (7.1 microM). The ferric-NTA complex was reduced by NADH with a molar stoichiometry of 2:1 for the iron complex to pyridine nucleotide ratio under near anaerobic conditions. Superoxide radicals were not apparently involved in the reduction of ferric iron under these conditions, despite measurable generation of superoxide under aerobic atmosphere. The reaction was inhibited by sulfhydryl reagents, was heat labile, and may account for reduction of ferric to ferrous iron during hepatic iron uptake from transferrin or from other iron sources.
Department of Medical Chemistry, University of Vienna Medical School, Austria.
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B
Scheiber
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Goldenberg
D000818:Animals; D002451:Cell Compartmentation; D004705:Endocytosis; D038181:FMN Reductase; D007425:Intracellular Membranes / Q000201:enzymology; D008099:Liver / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D009249:NADP / Q000378:metabolism; D051381:Rats; D013347:Subcellular Fractions / Q000201:enzymology; D013481:Superoxides / Q000378:metabolism
D009097:Multienzyme Complexes; D009243:NAD; D013481:Superoxides; D009249:NADP; D038181:FMN Reductase; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; C023903:ferric citrate iron reductase