A molecular dynamics investigation of the elastomeric restoring force in elastin

Area of Science:

• Biophysics
• Materials Science

Background:

• Elastin, a key biological elastomer, features a polypentapeptide structure with beta-bends.
• Its unique elastic properties are crucial for biological tissues.

Purpose of the Study:

• To investigate the structural dynamics and entropic contributions of elastin at various extension states.
• To elucidate the molecular mechanisms underlying elastin's elasticity.

Main Methods:

• Molecular dynamics simulations of hydrated elastin polypentapeptide polymers ((Val-Pro-Gly-Val-Gly)18).
• Analysis of backbone angle fluctuations and conformational entropy.
• Estimation of solvent-accessible surface area changes.

Main Results:

• Significant torsional motions in relaxed elastin were observed, particularly at residues linking beta-bends.
• These motions, involving crankshaft rotations, were reduced upon stretching.
• A decrease in conformational entropy and significant changes in solvent-accessible surface area were noted during stretching.

Conclusions:

• Hydrophobic interactions contribute to elastin's entropy at low extensions.
• Librational mechanisms, driven by reduced torsional motions, become dominant contributors to the elastic restoring force at higher extensions.