In dental medicine, there is a need for novel biomaterials for use in osseous and tooth reconstruction and in the regeneration of craniofacial and periodontal tissues. Our research is directed at understanding how natural biopolymers interact with biominerals to form composite materials. Our model system is the sea urchin spicule, a mineral matrix composite material that is comprised of calcite (CaCO3) and 45 matrix proteins. Recent developments indicate that the spicule matrix proteins apparently become """"""""entrapped"""""""" or intercalated within the calcite superlattice during the biomineralization process. As a result of this intercalation, the calcitic spicule exhibits increased resistance to fracture, compared to synthetic calcite. When fracture does occur, """"""""glassy"""""""" fracture properties are observed. These material properties would be ideally suited for dental materials applications. We propose an initial multidisciplinary investigation of SM50, an intercalation protein. Our goal is to determine the three-dimensional structure of -Gln-Pro-Gly- (QPG) and -Pro -Asn-Asn- Pro- (PNNP) sequence repeats contained within this protein. The primary tools for this study will be (A) NMR Spectroscopy, and, (B) Molecular Modeling and Simulation. In (A), we will synthesize peptide mimetics of the QPG and PNNP motifs, and perform NMR experiments to ascertain the solution conformational states for these sequence repeats. In (B), we will use computational algorithms to determine low-energy states for polypeptides derived from SM50 motif sequences. Using the structural information obtained from each peptide, we can extrapolate this data to the repeat regions of SM50, which comprise nearly 50% of the protein sequence. Using this """"""""buildup"""""""" model, we can then begin to explore how the SM50 structure might """"""""pack"""""""" within a calcitic superlattice, or, which regions of the protein may be available for protein-protein association. These approaches should provide us with information regarding the structure of the SM50 intercalation protein, and will eventually pave the way for the rational design of synthetic polymers that will perform the function of intercalation proteins in dental materials.
| Xu, G; Evans, J S (1999) Model peptide studies of sequence repeats derived from the intracrystalline biomineralization protein, SM50. I. GVGGR and GMGGQ repeats. Biopolymers 49:303-12 |
| Xu, G; Evans, J S (1996) The application of ""excitation sculpting"" in the construction of selective one-dimensional homonuclear coherence-transfer experiments. J Magn Reson B 111:183-5 |
