Solid State NMR Structure/Function Studies of Amelogenin

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DESCRIPTION: The overall goal of this research is to elucidate the structure-function relationships of the biomineralization proteins driving the formation of enamel. Enamel is the most highly ordered biomineralization crystal and is uniquely designed to handle abrasions and mechanical stress. As with many biomineralization processes, though, very little is understood about the mechanisms controlling enamel nucleation and growth, although the presence of proteins has been deemed critical. Enamelins, tuftelins, ameloblastins and amelogenins are all present during enamel formation and all have been suggested as candidates for crystal nucleation. Amelogenin consists of 90% of the protein present during enamel growth, is necessary for proper enamel formation and is likely a major contributor in the development of the calcium phosphate crystal. In addition to a possible nucleation role, amelogenin forms unique self assembled nanospheres which are thought to be tied to the elongated growth of enamel crystals during development. Structure-function relationships will be elucidated primarily using solid state NMR (SSNMR), Quartz Crystal Microbalance (QCM) and constant composition kinetics (CCK) to study the immobilized protein under the wide variety of conditions found in developing enamel. SSNMR will be used to accurately determine the secondary structure, dynamics and amino acids important in binding the protein or protein self assembly to calcium phosphates. QCM will be used to investigate nucleation rates and protein binding kinetics. The surface specific interactions will be probed with CCK to determine crystal growth inhibition and change in crystal growth mechanism. Site directed mutations, shown to cause defects in enamel will also be studied, to further aid in understanding of the developing enamel interface. Correlating the SSNMR results with kinetic measurements will provide a great deal of insight into the importance of the secondary and quaternary structure of amelogenin in formation of the enamel matrix. These studies will yield an in depth understanding of the molecular level processes involved in the formation of teeth, and more generally will provide basic insight into protein/crystal interactions.