Monte Carlo simulations of ion selectivity in a biological Na channel: Charge-space competition

Dezső Boda, David D. Busath, Bob Eisenberg, Douglas Henderson, Wolfgang Nonner

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

Na channels that produce the action potentials of nerve and muscle include a selectivity filter formed by both positively and negatively charged amino acid residues in a molecular pore. Here we present Monte Carlo simulations of equilibrium ion absorption in such a system. Ions are treated as charged hard spheres in a uniform dielectric. Tethered carboxylate and amino groups known to line the selectivity filter of the Na channel are represented as charged hard spheres and restricted to the filter region of the channel. Consistent with experiments, we find (1) that absorption of Ca2+ into the filter exceeds absorption of Na+ only when the concentration of Ca2+ is some tenfold larger than physiological; (2) the model channel absorbs smaller alkali metal ions preferentially compared to larger ones. The alkali metal selectivity involves volume exclusion of larger ions from the center of the filter region.

Original languageEnglish
Pages (from-to)5154-5160
Number of pages7
JournalPhysical Chemistry Chemical Physics
Volume4
Issue number20
DOIs
Publication statusPublished - Jan 1 2002

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ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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