Ferritin: A Versatile Building Block for Bionanotechnology

Protein structures such as ferritin in combination with synthetic as well as genetic alterations has proven to be highly interesting for the production of new materials. Ferritin describes a family of iron storage proteins with ubiquitous distribution among all life forms, with the notable exception of yeast and they are the most abundant members of the ferritin-like superfamily and may have developed from a rubrerythrin-like ancestor protein with two homologous pairs of antiparallel helices as main structural feature. The protein shell of mammalian ferritin is usually heterogeneous and consists of a mixture of two subunits of about 21 kDa, termed H for heavy (predominant in heart) and of about 19 kDa, termed L for light chain (predominant in liver), with around 55% amino acid homology for human H- and Lferritin. Apoferritin can be readily disassembled and reassembled by reducing the pH to a value as low as pH 2 and increasing it above pH 7, respectively. Holo-ferritin exhibits a remarkable affinity for anions and some nonferrous metal ions. Direct demineralization of the iron core in ferritins can be induced with strong Fe(III) chelators.