Separation of Iron-containing Ferritin from Horse-spleen into Three Distinct Fractions by Starch-gel Electrophoresis

ULTRACENTRIFUGAL investigations 1 have shown that ferritin which was prepared from horse-spleen by Granick's method 2 is not a chemical entity but consists of a mixture of a colourless component and a heterogeneous coloured material. The colourless component is an iron-free, fairly homogeneous protein ( S 20 = 17.6;mol. wt. 465,000), moving with a sharp boundary in the ultracentrifuge, and is identical with apoferritin prepared by Granick and Michaelis 3 . The coloured iron-containing material, ferritin, is rather heterogeneous and sediments with a widely spread boundary.