Protein nanoribbons template enamel mineralization

How does enamel achieve its remarkable microstructure? This study reveals that the cleaved enamel protein amelogenin adopts a ribbon-like supramolecular structure that controls the growth of mineral into nanofibers. Protein nanoribbons of 15 to 20 nm in width were identified in dental enamel and replicated from a recombinant protein mimicking an enzymatic cleavage product of human amelogenin. In mineralization experiments, these protein structures templated the growth of highly oriented apatite nanofibers along their backbone from an amorphous precursor. In accordance with the natural process of enamel development, this in vitro model suggests that the ability of amelogenin nanoribbons to guide fibrous apatite growth is regulated by enzymatic processing and their interaction with acidic nonamelogenin proteins in the developing enamel matrix.