Effects of recombinant amelogenin on hydroxyapatite formation in vitro

To determine the role of amelogenin in the mineralization of dental enamel, the effects of the recombinant mouse amelogenin rM179 on in vitro hydroxyapatite formation have been studied. In a steady-state agarose gel assay for hydroxyapatite nucleation, rM179 lacked significant activity at concentrations up to 300 microgram/ml. In an autotitration assay for inhibition of de novo hydroxyapatite formation, rM179 had no significant activity at concentrations up to 30 microgram/ml. Using selected-area dark-field electron microscopy, it was shown that rM179, at concentrations up to 30 microgram/ml, did not significantly affect the length of hydroxyapatite crystals formed in steady-state agarose gels. These findings suggest that amelogenins do not possess the specific crystal-modulating properties characteristic of certain acidic mineralized tissue proteins proteins.