Abstract

Elastin undergoes an “inverse temperature transition” such that it becomes more ordered as the temperature increases. To investigate the molecular basis for this behavior, molecular dynamics simulations were conducted above and below the transition temperature. Simulations of a 90-residue elastin peptide, (VPGVG)₁₈, with explicit water molecules were performed at seven different temperatures between 7 and 42 °C, for a total of 80 ns. Beginning from an idealized β-spiral structure, hydrophobic collapse was observed over a narrow temperature range in the simulations. Moreover, simulations above and below elastin’s transition temperature indicate that elastin has more turns and distorted β-structure at higher temperatures. Water was critical to the inverse temperature transition and elastin-associated water molecules can be divided into three categories: those closely associated with βII turns; those that form hydrogen bonds with the main-chain groups; and those hydrating the hydrophobic side-chains. Water-swollen, monomeric elastin above the transition temperature is best described as a compact amorphous structure with distorted β-strands, fluctuating turns, buried hydrophobic residues, and main-chain polar atoms that participate in hydrogen bonds with water. Below the transition temperature, elastin is expanded with 40 % local β-spiral structure. Overall the simulations are in agreement with experiment and therefore appear to provide an atomic-level description of the conformational properties of elastin monomers and the basis for their elastomeric properties.

Author Keywords: inverse temperature transition; hydrophobic collapse; elastin-associated water; molecular dynamics simulations; β-spiral

Abbreviations: CD, circular dichroism; MD, molecular dynamics

Article Outline

• Introduction

• Results and discussion

• Global temperature-dependent behavior of (VPGVG)₁₈

• Main characteristics of elastin structure in water

• Secondary structure analysis

• Hydrophobic collapse and elastin-associated water

• Comparison of elastin models

• Materials and methods

• Acknowledgements

• References

Corresponding author

¹ Edited by A. R. Fersht