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Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation.

Publication ,  Journal Article
Chutia, S; Rossi, M; Blum, V
Published in: The journal of physical chemistry. B
December 2012

We study the initial steps of the interaction of water molecules with two unsolvated peptides: Ac-Ala(5)-LysH(+) and Ac-Ala(8)-LysH(+). Each peptide has two primary candidate sites for water adsorption near the C-terminus: a protonated carboxyl group and the protonated ammonium group of LysH(+), which is fully hydrogen-bonded (self-solvated) in the absence of water. Earlier experimental studies have shown that H(2)O adsorbs readily at Ac-Ala(5)-LysH(+) (a non-helical peptide) but with a much lower propensity at Ac-Ala(8)-LysH(+) (a helix) under the same conditions. The helical conformation of Ac-Ala(8)-LysH(+) has been suggested as the origin of the different behavior. We here use first-principles conformational searches (all-electron density functional theory based on a van der Waals corrected version of the PBE functional, PBE+vdW) to study the microsolvation of Ac-Ala(5)-LysH(+) with one to five water molecules and the monohydration of Ac-Ala(8)-LysH(+). In both cases, the most favorable water adsorption sites break intramolecular hydrogen bonds associated with the ammonium group, in contrast to earlier suggestions in the literature. A simple thermodynamic model yields Gibbs free energies ΔG(0)(T) and equilibrium constants in agreement with experiments. A qualitative change of the first adsorption site does not occur. For few water molecules, we do not consider carboxyl deprotonation or finite-temperature dynamics, but in a liquid solvent, both effects would be important. Exploratory ab initio molecular dynamics simulations illustrate the short-time effects of a droplet of 152 water molecules on the initial unsolvated conformation, including the deprotonation of the carboxyl group. The self-solvation of the ammonium group by intramolecular hydrogen bonds is lifted in favor of a solvation by water.

Duke Scholars

Published In

The journal of physical chemistry. B

DOI

EISSN

1520-5207

ISSN

1520-6106

Publication Date

December 2012

Volume

116

Issue

51

Start / End Page

14788 / 14804

Related Subject Headings

  • Water
  • Thermodynamics
  • Solvents
  • Peptides
  • Molecular Dynamics Simulation
  • Methylamines
  • Lysine
  • Hydrogen Bonding
  • Adsorption
  • 51 Physical sciences
 

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Chutia, S., Rossi, M., & Blum, V. (2012). Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation. The Journal of Physical Chemistry. B, 116(51), 14788–14804. https://doi.org/10.1021/jp3098268
Chutia, Sucismita, Mariana Rossi, and Volker Blum. “Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation.The Journal of Physical Chemistry. B 116, no. 51 (December 2012): 14788–804. https://doi.org/10.1021/jp3098268.
Chutia S, Rossi M, Blum V. Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation. The journal of physical chemistry B. 2012 Dec;116(51):14788–804.
Chutia, Sucismita, et al. “Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation.The Journal of Physical Chemistry. B, vol. 116, no. 51, Dec. 2012, pp. 14788–804. Epmc, doi:10.1021/jp3098268.
Chutia S, Rossi M, Blum V. Water adsorption at two unsolvated peptides with a protonated lysine residue: from self-solvation to solvation. The journal of physical chemistry B. 2012 Dec;116(51):14788–14804.
Journal cover image

Published In

The journal of physical chemistry. B

DOI

EISSN

1520-5207

ISSN

1520-6106

Publication Date

December 2012

Volume

116

Issue

51

Start / End Page

14788 / 14804

Related Subject Headings

  • Water
  • Thermodynamics
  • Solvents
  • Peptides
  • Molecular Dynamics Simulation
  • Methylamines
  • Lysine
  • Hydrogen Bonding
  • Adsorption
  • 51 Physical sciences