title: The iron-binding properties of hen ovotransferrin.
abstract: 1. The distribution of iron between the two iron-binding sites in partially saturated ovotransferrin was studied by labelling with 55Fe and 59Fe and by gel electrophoresis in a urea-containing buffer. 2. When iron is added in the form of chelate complexes at alkaline pH, binding occurs preferentially at the N-terminal binding site. In acid, binding occurs preferentially at the C-terminal site. 3. When simple iron donors (ferric and ferrous salts) are used the metal is distributed at random between the binding sites, as judged by the gel-electrophoresis method. The double-isotope method shows a preference of ferrous salts for the N-terminal site. 4. Quantitative treatment of the results of double-isotope labelling suggests that in the binding of iron to ovotransferrin at alkaline pH co-operative interactions between the sites occur. These interactions are apparently absent in the displacement of copper and in the binding of iron at acid pH.
mesh_terms: D001665:Binding Sites; D003207:Conalbumin / Q000378:metabolism*; D004527:Egg Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D007501:Iron / Q000378:metabolism*; D007504:Iron Radioisotopes; D011485:Protein Binding
chemical_list: D004527:Egg Proteins; D007504:Iron Radioisotopes; D003207:Conalbumin; D007501:Iron