Cheng Zhu
University of Colorado Boulder, USA
Title: Nanoribbon assembly of amelogenin secondary structures act as a low-energy template for mineral nucleation
Biography
Biography: Cheng Zhu
Abstract
Protein scaffolds can direct the mineralization of the amorphous precursors, but the templating mechanism remains elusive. Since the amyloid-like amelogenin nanoribbons of tooth enamel can guide apatite mineralization, we keep a watchful eye on the amelogenin sub-segments including an amyloid-like domain, nanoribbon conformation and function. The impact of nanoribbon structure and chemistry on amorphous calcium phosphate (ACP) nucleation were investigated by molecular dynamics (MD) simulations and in situ atomic force microscopy (AFM). The conformations of the peptide nanoribbons formed on highly oriented pyrolytic graphite (HOPG) were confirmed by MD simulations, where the hydrophobic groups bind to the HOPG while hydrophilic residues point to the solutions. MD simulations also confirm that all the sequences can help nucleate ACP, especially on those with phosphorylated-serine and more hydrophilic residues. The distribution of hydrophilic residues matches the structure of the multi-ion clusters comprising ACP. The AFM results show that all sequences substantially reduce nucleation barriers by creating low-energy interfaces, while phosphorylated-serine dramatically enhances kinetic factors associated with Ca ion binding. These findings provide crucial insights into the templating mechanism and nucleation chemistry, uncovering the structure-function relationships underlying amelogenin biomineralization. It also shows guiding significance of synthesizing hybrid materials of biochemistry and bioengineering.