  We report on the direct measurement of the correlation times of the protein
backbone carbons and proximal waters of hydration in mechanically strained
elastin by nuclear magnetic resonance methods. The experimental data indicate a
decrease in the correlation times of the carbonyl carbons as the strain on the
biopolymer is increased. These observations are in good agreement with short
4ns molecular dynamics simulations of (VPGVG)3, a well studied mimetic peptide
of elastin. The experimental results also indicate a reduction in the
correlation time of proximal waters of hydration with increasing strain applied
to the elastomer. A simple model is suggested that correlates the increase in
the motion of proximal waters of hydration to the increase in frequency of
libration of the protein backbone that develops with increasing strain.
Together, the reduction in the protein entropy accompanied with the increase in
entropy of the proximal waters of hydration with increasing strain, support the
notion that the source of elasticity is driven by an entropic mechanism arising
from the change in entropy of the protein backbone.
