Energetics of ion competition in the DEKA selectivity filter of neuronal sodium channels

D. Boda, G. Leaf, J. Fonseca, B. Eisenberg

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The energetics of ionic selectivity in the neuronal sodium channels is studied. A simple model constructed for the selectivity 1lter of the channel is used. The selectivity 1lter of this channel type contains aspartate (D), glutamate (E), lysine (K), and alanine (A) residues (the DEKA locus). We use Grand Canonical Monte Carlo simulations to compute equilibrium binding selectivity in the selectivity 1lter and to obtain various terms of the excess chemical potential from a particle insertion procedure based on Widom's method. We show that K+ ions in competition with Na+ are eWciently excluded from the selectivity 1lter due to entropic hard sphere exclusion. The dielectric constant of protein has no effect on this selectivity. Ca2+ ions, on the other hand, are excluded from the 1lter due to a free energetic penalty which is enhanced by the low dielectric constant of protein.

Original languageEnglish
JournalCondensed Matter Physics
Volume18
Issue number1
DOIs
Publication statusPublished - Jan 1 2015

    Fingerprint

Keywords

  • Ion channel
  • Monte carlo
  • Primitive model electrolytes
  • Selectivity

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Physics and Astronomy (miscellaneous)

Cite this