The superoxide-dependent transfer of iron from ferritin to transferrin and lactoferrin

By the use of gel filtration and [59Fe]ferritin, apotransferrin and apolactoferrin were shown to take up iron released from ferritin by superoxide generated by hypoxanthine and xanthine oxidase. Apotransferrin also inhibited uptake of released iron by ferrozine. Ferritin and the xanthine oxidase system induced lipid peroxidation in phospholipid liposomes. This peroxidation was inhibited by apotransferrin or apolactoferrin. Thus, although superoxide and other free radicals can release iron from ferritin, either iron-binding protein, if present, should take up this iron and prevent its catalysing subsequent oxidative reactions.

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Inhibition of lipid peroxidation by the iron-binding protein lactoferrin

Biochemical Journal ◽

10.1042/bj1990259 ◽

1981 ◽

Vol 199 (1) ◽

pp. 259-261 ◽

Cited By ~ 169

Author(s):

John M. C. Gutteridge ◽

Suzanne K. Paterson ◽

Anthony W. Segal ◽

Barry Halliwell

Keyword(s):

Lipid Peroxidation ◽

Ascorbic Acid ◽

Oxidative Damage ◽

Metal Ion ◽

Binding Protein ◽

Iron Binding ◽

Iron Binding Protein

Lactoferrin containing physiological amounts of iron is an inhibitor of lipid peroxidation induced by iron(III) salts and ascorbic acid. It might therefore help to protect neutrophils, inflammatory foci and secretions from metal-ion-dependent oxidative damage.

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Cytosol intermediates in the transport of iron

Blood ◽

10.1182/blood.v55.6.1051.bloodjournal5561051 ◽

1980 ◽

Vol 55 (6) ◽

pp. 1051-1055 ◽

Cited By ~ 1

Author(s):

MT Nunez ◽

ES Cole ◽

J Glass

Keyword(s):

Molecular Weight ◽

Plasma Membrane ◽

Binding Protein ◽

Gel Filtration ◽

Apparent Molecular Weight ◽

Iron Binding ◽

The Third ◽

Initial Values ◽

Iron Supply ◽

Iron Binding Protein

Three 59Fe-labeled nonheme components of the cytosol were identified when rabbit reticuloyctes were incubated with 59Fe-labeled plasma under conditions in which the iron supply was not limiting. Two of these components were identified as ferritin and transferrin. The latter was characterized by gel filtration as having apparent molecular weight higher than transferrin, indicating that the transferrin may be complexed to another moiety. The third component, referred to as iron- binding protein-I (IBP-I), is as yet uncharacterized. When the reticulocytes were incubated with unlabeled plasma after pulse-labeling with 59Fe-labeled plasma, 59Fe radioactivity in these cytosol components decreased; after 15 min of chase, the 59Fe in ferritin, transferrin, and IBP-I fell to 64.6%, 26.5%, and 65.8% of the initial values, respectively. A good correlation existed between the decrease of 59Fe in these three nonheme compartments and the associated increase in 59Fe-heme. The data presented suggest that cytosol ferritin, transferrin, and IBP-I are intermediates in the transport of 59Fe from the plasma membrane to the mitochondria.

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Isolation, purification and characterization of an iron-binding protein from the horseshoe crab (Limulus polyphemus)

Biochemical Journal ◽

10.1042/bj2520151 ◽

1988 ◽

Vol 252 (1) ◽

pp. 151-157 ◽

Cited By ~ 6

Author(s):

R Topham ◽

B Cooper ◽

S Tesh ◽

G Godette ◽

C Bonaventura ◽

...

Keyword(s):

Molecular Mass ◽

Horseshoe Crab ◽

Binding Protein ◽

Polyacrylamide Gel Electrophoresis ◽

Gel Filtration ◽

Limulus Polyphemus ◽

Evolutionary Development ◽

Iron Binding ◽

Oxygen Carriers ◽

Iron Binding Protein

The presence of an iron-binding protein in the haemolymph of the horseshoe crab, Limulus polyphemus, was detected by gel filtration of 59Fe-labelled haemolymph. Lysis of amoebocytes did not change the amount of iron-binding protein in haemolymph samples. The protein was purified to homogeneity by ion-exchange chromatography. The molecular mass of the purified protein was estimated to be 282,000 +/- 10,000 Da by gel filtration and analytical ultracentrifugation. SDS/polyacrylamide-gel electrophoresis demonstrated that the protein is composed of ten subunits having a molecular mass of 28,000 +/- 2,000 Da. The purified, unlabelled protein efficiently sequestered 59Fe in the absence of haemolymph indicating that no other haemolymph factors are required for the incorporation of iron into the protein. No 59Fe was removed from the purified protein with EDTA or 2,2′-bipyridyl. Partial removal of 59Fe was achieved by dialysis with nitrilotriacetic acid or desferal. Analysis of the iron-loaded protein indicated that each subunit has the capacity to bind two iron atoms with high affinity. The isolation of an iron-binding protein from L. polyphemus supports the proposal that such proteins are an ancient evolutionary development not necessarily linked to the appearance of iron proteins which serve as oxygen carriers.

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Cytosol intermediates in the transport of iron

Blood ◽

10.1182/blood.v55.6.1051.1051 ◽

1980 ◽

Vol 55 (6) ◽

pp. 1051-1055 ◽

Cited By ~ 23

Author(s):

MT Nunez ◽

ES Cole ◽

J Glass

Keyword(s):

Molecular Weight ◽

Plasma Membrane ◽

Binding Protein ◽

Gel Filtration ◽

Apparent Molecular Weight ◽

Iron Binding ◽

The Third ◽

Initial Values ◽

Iron Supply ◽

Iron Binding Protein

Abstract Three 59Fe-labeled nonheme components of the cytosol were identified when rabbit reticuloyctes were incubated with 59Fe-labeled plasma under conditions in which the iron supply was not limiting. Two of these components were identified as ferritin and transferrin. The latter was characterized by gel filtration as having apparent molecular weight higher than transferrin, indicating that the transferrin may be complexed to another moiety. The third component, referred to as iron- binding protein-I (IBP-I), is as yet uncharacterized. When the reticulocytes were incubated with unlabeled plasma after pulse-labeling with 59Fe-labeled plasma, 59Fe radioactivity in these cytosol components decreased; after 15 min of chase, the 59Fe in ferritin, transferrin, and IBP-I fell to 64.6%, 26.5%, and 65.8% of the initial values, respectively. A good correlation existed between the decrease of 59Fe in these three nonheme compartments and the associated increase in 59Fe-heme. The data presented suggest that cytosol ferritin, transferrin, and IBP-I are intermediates in the transport of 59Fe from the plasma membrane to the mitochondria.

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