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Ion pairing as a possible clue for discriminating between sodium and potassium in biological and other complex environments.

Authors
  • Jagoda-Cwiklik, Barbara
  • Vacha, Robert
  • Lund, Mikael
  • Srebro, Monika
  • Jungwirth, Pavel
Type
Published Article
Journal
The Journal of Physical Chemistry B
Publisher
American Chemical Society
Publication Date
Dec 27, 2007
Volume
111
Issue
51
Pages
14077–14079
Identifiers
PMID: 18052278
Source
Medline
License
Unknown

Abstract

For a series of biologically relevant anions, we present free energy changes upon replacing potassium with sodium in a contact ion pair. Calculations performed using a combination of molecular dynamics simulations and ab initio methods demonstrate the ordering of anions in a Hofmeister series. Small anionic groups such as carboxylates preferentially pair with sodium, while intermediate cases such as chloride or monovalent phosphate exhibit almost no specificity, and large anions (e.g., methylsulfonate) prefer potassium over sodium. These results can rationalize different behavior of Na+ versus K+ at the surface of hydrated proteins, DNA, and reversed micelles.

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