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Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides

Publication ,  Journal Article
Cho, YH; Zhang, YJ; Christensen, T; Sagle, LB; Chilkoti, A; Cremer, PS
Published in: Journal Of Physical Chemistry B
November 2008

The modulation of the lower critical solution temperature (LCST) of two elastin-like polypeptides (ELPs) was investigated in the presence of 11 sodium salts that span the Hoftneister series for anions. It was found that the hydrophobic collapse/aggregation of these ELPs generally followed the series. Specifically, kosmotropic anions decreased the LCST by polarizing interfacial water molecules involved in hydrating amide groups on the ELPs. On the other hand, chaotropic anions lowered the LCST through a surface tension effect. Additionally, chaotropic anions showed salting-in properties at low salt concentrations that were related to the saturation binding of anions with the biopolymers. These overall mechanistic effects were similar to those previously found for the hydrophobic collapse and aggregation of poly(N-isopropylacrylamide), PNIPAM. There is, however, a crucial difference between PNIPAM and ELPs. Namely, PNIPAM undergoes a two-step collapse process as a function of temperature in the presence of sufficient concentrations of kosmotropic salts. By contrast, ELPs undergo collapse in a single step in all cases studied herein. This suggests that the removal of water molecules from around the amide moieties triggers the removal of hydrophobic hydration waters in a highly coupled process. There are also some key differences between the LCST behavior of the two ELPs. Specifically, the more hydrophilic ELP V(5)A(2)G(3)-120 construct displays collapse/aggregation behavior that is consistent with a higher concentration of anions partitioning to polymer/aqueous interface as compared to the more hydrophobic ELP V-5-120. It was also found that larger anions could bind with ELP V(5)A(2)G(3)-120 more readily in comparison with ELP V-5-120. These latter results were interpreted in terms of relative binding site accessibility of the anion for the ELP.

Duke Scholars

Published In

Journal Of Physical Chemistry B

ISSN

1520-6106

Publication Date

November 2008

Volume

112

Issue

44

Start / End Page

13765 / 13771

Related Subject Headings

  • Temperature
  • Salts
  • Phase Transition
  • Peptides
  • Molecular Structure
  • Elastin
  • Anions
  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences
 

Citation

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Cho, Y. H., Zhang, Y. J., Christensen, T., Sagle, L. B., Chilkoti, A., & Cremer, P. S. (2008). Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides. Journal Of Physical Chemistry B, 112(44), 13765–13771.
Cho, Y. H., Y. J. Zhang, T. Christensen, L. B. Sagle, A. Chilkoti, and P. S. Cremer. “Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides.” Journal Of Physical Chemistry B 112, no. 44 (November 2008): 13765–71.
Cho YH, Zhang YJ, Christensen T, Sagle LB, Chilkoti A, Cremer PS. Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides. Journal Of Physical Chemistry B. 2008 Nov;112(44):13765–71.
Cho, Y. H., et al. “Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides.” Journal Of Physical Chemistry B, vol. 112, no. 44, Nov. 2008, pp. 13765–71.
Cho YH, Zhang YJ, Christensen T, Sagle LB, Chilkoti A, Cremer PS. Effects of Hofmeister Anions on the Phase Transition Temperature of Elastin-like Polypeptides. Journal Of Physical Chemistry B. 2008 Nov;112(44):13765–13771.
Journal cover image

Published In

Journal Of Physical Chemistry B

ISSN

1520-6106

Publication Date

November 2008

Volume

112

Issue

44

Start / End Page

13765 / 13771

Related Subject Headings

  • Temperature
  • Salts
  • Phase Transition
  • Peptides
  • Molecular Structure
  • Elastin
  • Anions
  • 51 Physical sciences
  • 40 Engineering
  • 34 Chemical sciences