Sequence Directionality Dramatically Affects LCST Behavior of Elastin-Like Polypeptides.

Published

Journal Article

Elastin-like polypeptides (ELP) exhibit an inverse temperature transition or lower critical solution temperature (LCST) transition phase behavior in aqueous solutions. In this paper, the thermal responsive properties of the canonical ELP, poly(VPGVG), and its reverse sequence poly(VGPVG) were investigated by turbidity measurements of the cloud point behavior, circular dichroism (CD) measurements, and all-atom molecular dynamics (MD) simulations to gain a molecular understanding of mechanism that controls hysteretic phase behavior. It was shown experimentally that both poly(VPGVG) and poly(VGPVG) undergo a transition from soluble to insoluble in aqueous solution upon heating above the transition temperature ( Tt). However, poly(VPGVG) resolubilizes upon cooling below its Tt, whereas the reverse sequence, poly(VGPVG), remains aggregated despite significant undercooling below the Tt. The results from MD simulations indicated that a change in sequence order results in significant differences in the dynamics of the specific residues, especially valines, which lead to extensive changes in the conformations of VPGVG and VGPVG pentamers and, consequently, dissimilar propensities for secondary structure formation and overall structure of polypeptides. These changes affected the relative hydrophilicities of polypeptides above Tt, where poly(VGPVG) is more hydrophilic than poly(VPGVG) with more extended conformation and larger surface area, which led to formation of strong interchain hydrogen bonds responsible for stabilization of the aggregated phase and the observed thermal hysteresis for poly(VGPVG).

Full Text

Duke Authors

Cited Authors

  • Li, NK; Roberts, S; Quiroz, FG; Chilkoti, A; Yingling, YG

Published Date

  • July 2018

Published In

Volume / Issue

  • 19 / 7

Start / End Page

  • 2496 - 2505

PubMed ID

  • 29665334

Pubmed Central ID

  • 29665334

Electronic International Standard Serial Number (EISSN)

  • 1526-4602

International Standard Serial Number (ISSN)

  • 1525-7797

Digital Object Identifier (DOI)

  • 10.1021/acs.biomac.8b00099

Language

  • eng