title: The cooperation of enamelin and amelogenin in controlling octacalcium phosphate crystal morphology.
abstract: Enamel matrix proteins, including the most abundant amelogenin and lesser amounts of enamelin, ameloblastin, and proteinases, play vital roles in controlling crystal nucleation and growth during enamel formation. The cooperative action between amelogenin and the 32-kDa enamelin is critical to regulating the growth morphology of octacalcium phosphate crystals. Using biophysical methods, we investigated the interaction between the 32-kDa enamelin and recombinant pig amelogenin 148 (rP148) at pH 6.5 in phosphate-buffered saline (PBS). Dynamic light scattering results showed a trend of increasing particle size in the mixture with the addition of enamelin to amelogenin. Upon addition of the 32-kDa enamelin, the shift and intensity decrease in the ellipticity minima of rP148 in the circular dichroism spectra of rP148 illustrated a direct interaction between the 2 proteins. In the fluorescence spectra, the maximum emission of rP148 was blue shifted from 335 to 333 nm in the presence of enamelin as a result of complexation of the 2 proteins. Our results demonstrate that the 32-kDa enamelin has a close association with amelogenin at pH 6.5 in PBS buffer. Our present study provides novel insights into the possible cooperation between enamelin and amelogenin in macromolecular coassembly and in controlling enamel mineral formation.
authors.affiliation: Center for Craniofacial Molecular Biology, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Daming
authors.initials: D
authors.lastname: Fan
authors.forename: Mayumi
authors.initials: M
authors.lastname: Iijima
authors.forename: Keith M
authors.initials: KM
authors.lastname: Bromley
authors.forename: Xiudong
authors.initials: X
authors.lastname: Yang
authors.forename: Shibi
authors.initials: S
authors.lastname: Mathew
authors.forename: Janet
authors.initials: J
authors.lastname: Moradian-Oldak
mesh_terms: D053523:Amelogenin / Q000378:metabolism*; D000818:Animals; D055592:Biophysical Phenomena; D002130:Calcium Phosphates / Q000737:chemistry* / Q000378:metabolism; D003198:Computer Simulation; D003460:Crystallization; D003746:Dental Enamel Proteins / Q000378:metabolism*; D008970:Molecular Weight; D011485:Protein Binding; D034421:Sus scrofa
chemical_list: D053523:Amelogenin; D002130:Calcium Phosphates; D003746:Dental Enamel Proteins; C038456:tuftelin; C022045:octacalcium phosphate