Protein-mineral interactions at the organic-inorganic interface in biominerals

点击翻译按钮获取中文摘要

Bones, teeth, otoconia, eggshells, snail and sea shells, corals and many other biomineralized structures in the plant and animal kingdoms arise from synergistic interactions between co-existing organic (usually proteins) and inorganic mineral phases. These composites have specialized properties, and hierarchically organized supramolecular assemblies that provide a framework for biomineralization. Negatively charged proteins may attain regulatory chemical complementarity by binding to mineral calcium at the organic-inorganic interface a mechanism to influence crystal growth processes. It is hypothesized that the molecular precision of such organic-inorganic interfacial interactions regulates crystal growth. My biomineralization research program focuses on specific proteins/peptides (notably osteopontin) that regulate mineral growth.***Intriguingly, amino acids, peptides and full-length proteins can be occluded within mineral crystals. Related to this, biomineralization can proceed initially through assembly of amorphous precursor nanoparticles forming within a confined, protein/peptide-rich reaction nanoenvironment. Within these nanoparticle domains, transformation towards a crystalline phase may occur over different length scales such that single crystals (by diffraction) can actually consist of aligned mineral nanoparticles, the fusion of which builds mesocrystals having occluded organics. This notion is in stark contrast to classical crystallization theory which postulates ion-by-ion attachment. My biomineralization research program compares these scenarios by exploring fundamental principles of how organics (amino acids, and relevant peptides and proteins) influence biomineralization.***We will compare two polymorphs of calcium carbonate crystals (calcite and vaterite) grown in the presence of osteopontin protein/peptides/amino acids to two biomineralized structures avian eggshell and mouse inner ear otoconia. To study the growth of calcium carbonate crystals in the presence of these organics, a variety of morphological, biochemical, immunochemical, cell biological/molecular, and characterization techniques will be used including: electron microscopy, atomic force microscopy, confocal microscopy, X-ray and electron diffraction, Canadian Light Source synchrotron analyses, Raman spectroscopy, immunocytochemistry on mouse otoconia, in vitro cell culture and crystal growth systems, mass spectroscopy, and RosettaSurface energy-minimization computational simulations.***With this mechanistic biomineralization information on how proteins and peptides bind to crystals to regulate their growth, we will be well-positioned to create tunable mineralization events that advance biomaterials and tissue engineering applications to the benefit of Canadians and citizens worldwide.**