The molecular structure and physical properties of elastin fibers as revealed by Raman microspectroscopy.
Raman microspectroscopy has been used to investigate the structure of alpha-elastin and fibrous elastin from ligament and aorta, and to explore changes associated with mechanical strain and temperature. Although no vibrational modes associated with cross-linking of the fibers could be identified, the secondary structure of dehydrated fibrous elastin was significantly different from alpha-elastin. The former differed from previous experimental measurements, but was close to the theoretical predictions with 36% beta-structures, 46% unordered, and 18% alpha-helix. Alpha-elastin contained 29% beta-structures, 53% unordered, and 18% alpha-helix. In nuchal fibers the amide I mode was polarized, consistent with the peptide bond. Strains of up to 60% in ligament fiber bundles resulted in no significant shifts in peak position or in secondary structure. Polarization measurements revealed that the peptide bonds and several side chains re-orientated closer to the fiber axis. Heating nuchal fibers to 60 degrees C to increase the energetic component of the elasticity was associated with a 30% increase in the proportion of beta-structures in the amide I band, a 50% increase in the amide III band, and a 50% reduction in the signal from bound water.
Green
Ellen
E
School of Physics, University of Exeter, Stocker Road, Exeter Devon EX4 4QL, UK. e.m.green@exeter.ac.uk
Ellis
Richard
R
Winlove
Peter
P
D000818:Animals; D002417:Cattle; D004549:Elastin / Q000737:chemistry*; D017433:Protein Structure, Secondary / Q000502:physiology; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013552:Swine
D004549:Elastin