Solid state NMR investigation of protein based biomaterials : Pacific hagfish slime thread and recombinant insect resilin

• Main Author: Depew, Thomas A.
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/29645

Nuclear Magnetic Resonance (NMR) was employed to investigate the structure and mechanics underlying the material properties of two remarkable biomaterials. Hydrated hagfish intermediate filament (IF) proteins were identified as having a two component nature, consistent with current structural models. One component is relatively rigid and immobile, the other rubbery, in which the protein backbone reorients with correlation times on the order of 60 ns. In order to investigate the role of calcium ions in the formation of hagfish slime, hagfish IFs were exposed to Ca²⁺ ions in solution. Energy dispersive X-ray spectroscopy revealed that the filaments did bind Ca ions after exposure. These results were variable and depended largely on the preparation technique. Recombinant resilins from Drosophila melanogaster and Anopheles gambiae were shown to have a highly elastic structure. Direct polarization spectra from each protein were analysed and the majority of the ¹³C peaks assigned successfully. Relaxation measurements report backbone correlation times on a scale of 2 to 8 ns, providing a molecular scale explanation the outstanding macroscopic resilience. Tyrosine residues in the resilin protein exhibited longer correlation times in the aromatic carbons, reflecting decreased mobility near dityrosine crosslinks.