Ferritin is a large, iron-storage heteropolymeric protein composed of two subunit types, light (FTL) and heavy (FTH1) polypeptides, which is expressed in most kinds of cells and co-assemble in different proportion in a tissue-specific manner. Ferritin is composed of 24 self-assembled polypeptide subunits and is characterized by the capacity to remove Fe (Ⅱ) from solution in the presence of oxygen. Recombinant human FTL was expressed in E.coli and purified by conventional chromatography techniques.