Monte Carlo simulation study of a system With a dielectric boundary: Application to calcium channel selectivity

Dezsö Boda, Tibor Varga, Douglas Henderson, David D. Busath, Wolfgang Nonner, Dirk Gillespie, Bob Eisenberg

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Equilibrium Monte Carlo simulations are reported for a model of a biological calcium channel in which the region that includes the channel and the selectivity filter has a different dielectric coefficient than that of the bath. These regions are separated by a sharp dielectric boundary. This simple geometry makes it possible to use the image charge method to incorporate polarization effects. We also include a description of changes in solvation energy that arise when ions move between different dielectrics; we use the Born description of hydration with empirical ionic radii that yield experimental hydration energies. In calculations of Ca2+vs. Na+ selectivity analogous to those of earlier work (Boda et al., Molec. Phys., 100, 2361 (2002)), we find that reducing the dielectric coefficient in the channel to values as low as 10 renders the channel model less calcium selective. Thus, this continuum description of polarization effects does not capture a delicate balance that seems to exist in biological channels between the energy that ions require for dehydration and the energy that ions gain by interaction with the charged groups in the pore.

Original languageEnglish
Pages (from-to)89-96
Number of pages8
JournalMolecular Simulation
Volume30
Issue number2-3
DOIs
Publication statusPublished - Feb 15 2004

Keywords

  • Biological channel
  • Monte Carlo stimulation
  • Poisson's equation
  • Polarization effect

ASJC Scopus subject areas

  • Chemistry(all)
  • Information Systems
  • Modelling and Simulation
  • Chemical Engineering(all)
  • Materials Science(all)
  • Condensed Matter Physics

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