Elastin structural understanding

We now well appreciate, of course, that polymers are virtually everywhere. Some of them occur naturally, and we continue to better understand their compositions, structures, and properties. Many of these materials have been used since the dawn of human existence, for food, obviously. Cellulose alone has been essential for clothing, fire, shelter, tools, weapons, writing, and art. Leather is probably the result of the first synthetic polymer reaction, essentially the crosslinking of protein (elastin). How we progressed over time to the Polymer Age is a fascinating series of stories, some of which are well worth recounting here. 

In one study, a model for elastin, the main protein that confers elasticity on solid structures in mammals, had its mobility investigated by examining 1H-13C and 1H dipolar couplings extracted from isotropic-anisotropic correlation experiments.29 The elastic properties of elastin are almost certainly conferred by molecular degrees of freedom, so such studies are important in understanding how this material works in Nature. The motional amplitudes determined from these experiments were found to depend upon the degree of hydration, with the mean square fluctuation angles found to be 11-18° in the dry protein and 16-21° in the 20% hydrated protein. 

The precise understanding of the structural nature of elastin remains elusive because the unusual physical properties of native elastin have prevented the use of traditional structural biology techniques. The hydrophobic domains are dominated by a pentapeptide repeat sequence of (Val-Pro-Gly-Val-Gly). This repeat sequence is believed to endow elastin its remarkable elastic properties, allowing continual expansion and contractions without loss of structural integrity (2). 

Solid state NMR has been employed to determine a number of distances and torsion angles in an elastin-mimetic peptide, (VPGVG)3, to understand the structural basis of elasticity. Elastin is an extracellular-matrix protein that imparts elasticity to tissues. The C. .. H and C. .. N distances between the V6 carbonyl and the V9 amide segment were measured using and C- H... 

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