Self-assembly of protein derived peptides
Degree GrantorUniversity of Canterbury
Degree NameDoctor of Philosophy
Self-assembling building blocks have become of increasing interest in the field of bionanotechnology due to their ability to self-assemble into defined geometrical shapes. Nature is abundant with examples of functional biological assemblies that are either rich in β-sheets or coiled coils. This research work investigates peptide sequences derived from simple protein interfaces, as molecular tectons for use in bionanotechnology. Protein interface sequences were chosen as a design source of peptide tectons, as they are naturally optimized to drive self-assembly in a highly controlled and regulated manner. This thesis work focused primarily on the simple β-continuous and the helical coiled coil protein interfaces. The peptide sequences designed from different protein-β interfaces all self-assembled into well-ordered nanostructures that were β-sheet rich and exhibited liquid crystallinity. SAXS and FTIR confirmed that the extended peptide nanostructures have the common architecture of β-sheets organized in a repetitive manner over long distances. The self-assembly of the peptide designed from the homodimer interface of bovine Prx3 was studied by thoughtfully altering appropriate residue in the peptide sequence. The peptide sequence was tolerant to the different variations introduced, with variant peptide β-sheet assemblies judged by ThT binding assays and SAXS consistent with the parent peptide. The self-assembling peptide sequences were used to template micron long nanotubes of the hPrx3 protein. Peptides designed from the coiled-coil interface of ovine keratin protein self-assembled into extended filament-like nanostructures with dimensions consistent with that of full-length keratin IFs. The results presented in this thesis work aid in understanding the natural self-assembly process through in vitro self-assembly of peptide mimics. The self-assembling peptide sequences were used to produce extended nanotubes and nanosheets of hPrx3 protein. Future work is needed to show the functionalization of such extended peptide and protein structures, though, this work showcases the potential of these peptide sequences as building blocks for hybrid biomaterials.