title: Binding of xylenol orange to transferrin. Demonstration of metal-anion linkage.
abstract: The iron transport protein, transferrin, binds two metal ions and, concomitantly, two carboxylate anions. The metal ion indicators, xylenol orange and semi-xylenol orange are carboxylate anions which exhibit a characteristic visible spectrum when attached to a metal. We prepared the ternary complexes VO2+-transferrin-xylenol orange and VO2+-transferrin-semi-xylenol orange. The EPR spectra show that the vanadyl ion is attached to the protein and the visible spectra show that the xylenol orange or semi-xylenol orange is attached to the metal. The implication is that in other metal-transferrin-anion complexes, the anion is directly attached to the metal.
mesh_terms: D055598:Chemical Phenomena; D002621:Chemistry; D005998:Glycine / Q000031:analogs & derivatives*; D009682:Magnetic Resonance Spectroscopy; D010636:Phenols; D013454:Sulfoxides; D014168:Transferrin; D014639:Vanadium; D014992:Xylenes
chemical_list: D010636:Phenols; D013454:Sulfoxides; D014168:Transferrin; D014992:Xylenes; D014639:Vanadium; C025406:semi-xylenol orange; C016833:xylenol orange; D005998:Glycine