title: Vanadium complexes of transferrin and ferritin in the rat.
abstract: Vanadium associates with serum transferrin of rats administered vanadyl(IV) sulfate or ammonium metavanadate(V) by gastric intubation. Low molecular weight species account for only 3% of the vanadium present in plasma. The element distributes between the two major isotransferrins in proportion to their concentrations. Rat apotransferrin binds both vanadium(IV) and vanadium(V), forming 2:1 metal-protein complexes in both instances. Although the two isotransferrins apparently differ in their physiological properties, they exhibit identical vanadyl(IV) (VO2+) EPR spectra, indicating identical or very similar metal binding sites for both proteins. In contrast to other transferrins, the two sites of the rat protein are spectroscopically indistinguishable and exhibit a VO2+ EPR spectrum similar to that of the C-terminal metal binding site of human serum transferrin. VO2+ EPR signals are observed with liver, spleen, and kidney tissue samples from animals maintained on a vanadium-supplemented diet. These signals arise from a specific intracellular VO2+ complex with the iron storage protein ferritin.
mesh_terms: D000818:Animals; D001665:Binding Sites; D003720:Densitometry; D004578:Electron Spin Resonance Spectroscopy; D005260:Female; D005293:Ferritins / Q000097:blood*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D013154:Spleen / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism*; D014639:Vanadium / Q000097:blood*
chemical_list: D014168:Transferrin; D014639:Vanadium; D005293:Ferritins