The cooperative effect of amelogenin and enamelin in the nucleation of calcium phosphate

Amelogenin is the major matrix proteins templating the nucleation of numerous calcium phosphate phases during enamel formation. Besides matrix protein, the other proteins like enamelin are also believed to have important role in the formation of enamel apatite. The delicate enamel architecture is believed to form under the control of amelogenin together with other non-amelogenous proteins including enamelin. Thus, understanding the interplay between amelogenin and enamelin may enable us to manufacture complex protein-mineral structure for tissue engineering. Here the nucleation of calcium phosphate on these surfaces is studied by in-situ AFM. The result showed that the nucleation rate of calcium phosphate showes an optimal enamelin/amelogenin ratio, when the enamelin/amelogenin ratio is below the critical value, nucleation rate increase as the enamelin increase, while above the critical value, the nucleation is inhibited. The reason for existence of such critical value is proposed and proved by gold nanoparticle labeling.