The isoelectric fractionation of hen's-egg ovotransferrin

Abstract

Hen ovotransferrin was examined by isoelectric fractionation. The major component observed in starch-gel electrophoresis can be isolated from the minor component. When non-saturating amounts of iron are added to ovotransferrin, isoelectric fractionation demonstrates the existence of 3 molecular species corresponding to the metal-free protein, the one-iron-atom-protein complex and the 2-iron-atoms-protein complex. Isoelectric fractionation of human serum labelled with 59Fe suggests that the transferrin of normal human serum also exists as metal-free protein, the 1-iron-atom-protein complex and the 2-iron-atoms-protein complex. It is concluded that the binding constants for the 1st and 2nd iron atoms are similar.