Effect of Pif80 Protein Fragments on the Mineralization Process of Calcium Carbonate
Date Issued
2015
Date
2015
Author(s)
Du, Yuan-Peng
Abstract
Biomineral is a composite material in organisms and it comprises an inorganic part as well as biomolecules like proteins and polysaccharides. These biomolecules can precisely control the crystal polymorphism and crystallization sites. However, the relationship between the two diverse organic and inorganic phases is still obscure and waiting to be explored because of lacking a good model system for study. In this thesis we have established a model system for investigating biomineralization process from the perspectives of biophysics and crystal-growth theory. Our model peptides were synthesized as motivated by the repeated sequence (DDRK) in Pif80, which is a crucial protein controlling the formation of the aragonitic nacreous layer in Pinctada fucata. We found that the Pif80 fragments can specifically associate with the aragonite phase of calcium carbonate and their binding propensity is highly dependent on the number of the repetition of DDRK sequence. These biomimetic peptide-mineral composites prepared here enable us to further utilize solid-state nuclear magnetic resonance to address the conformation of Pif80 peptides. In the view of crystal-growth theory, we employed β-chitin as a substrate with various Pif80 fragments to mimic the nacreous environment in order to investigate how biomolecules affect the crystallization of CaCO3 in nacre. Scanning electron microscopic analysis has shown that Pif80 peptides can induce the nucleation of aragonite on the β-chitin, which is distinct from the results without the substrate. Among the three peptides, Pif80-11 can increase the population densities of crystallites in the regions occupied by aragonite and we suspect this result is related to the higher binding affinity of Pif80-11. This binding effect probably reduces the energy barrier of nucleating aragonite and further induces the formation of aragonitic crystallites. We believe that the model system developed here can facilitate the future study in the mechanistic aspect of biomineralization that can be applied for material science.
Subjects
biomineralization
calcium carbonate
crystal growth theory
biophysics
Pif80 protein
solid-state nuclear magnetic resonance spectroscopy
nucleation
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-104-R02223108-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):3b4a5a1e6f351f270024740951ab0a3e