Characterization of the Structures of Small Peptides and their Interactions with Inorganic Minerals

Abstract

Proteins mediate the nucleation and growth of many biominerals, yet the specifics of these protein-mineral interactions are often poorly understood. The focus of this dissertation is to better understand these interactions via small peptide systems. The approach to this problem is multifaceted; peptide-mineral interactions are explored through various biomineralization systems and through surface adsorption. The biomineralization studies begin with R5, a well- studied biosilicification peptide that can produce uniform nanostructures of both silica (SiO2) and titania (TiO2). Then, model serine-lysine (S-K) peptides are investigated to further the understanding of biomimetic TiO2 formation. Surface adsorption studies are focused on the structure of SNa15, a mutated fragment of statherin (a salivary protein) as a function of mineral surface: hydroxyapatite (HAP), SiO2, and TiO2. Solid-state NMR (ssNMR) experiments used in the investigation of R5, the S-K peptides, and SNa15 are detailed here. 1D 13C CP MAS, 1D 15N CP MAS, and 2D 13C-13C DARR experiments are utilized, resulting in peptide structures for both the neat and mineral-complexed forms. Furthermore, side-chain chemical shifts are used to assess the degree to which various residues are in close proximity to the mineral phases.