| Summary: | 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.
|
|---|
