The Interaction of Iron-Conalbumin(Anion) Complexes with Chick Embryo Red Blood Cells

Equilibrium binding studies and iron transport rate studies of the interaction of conalbumin and transferrin with the chick embryo red cell have supported the following conclusions: (a) that the chick embryo red cell is comparable to the rabbit and human reticulocyte systems traditionally used for the study of the physiological function of the metal complexes of siderophilins; (b) that there may be two classes of binding sites on the chick embryo red cell membrane for Fe2conalbumin, one for which conalbumin competes and one for which it does not compete; (c) that the red cell membrane accepts iron from differiconalbumin at twice the rate as from monoferriconalbumins, suggesting that simultaneous transport takes place from the two iron-binding sites on the protein with respect to iron acquisition; and (d) that the substitution of oxalate for carbonate as the obligate anion in the Fe2conalbumin(anion)2 complex decreases the rate of iron uptake by the cell because the cell must release the anion from the protein complex before it is able to sequester the bound iron.