Skip to main content
PMC home page
Biophysical Journal logoLink to Biophysical Journal
. 1995 Feb;68(2):427–433. doi: 10.1016/S0006-3495(95)80204-3

Extended dipolar chain model for ion channels: electrostriction effects and the translocational energy barrier.

M Sancho 1, M B Partenskii 1, V Dorman 1, P C Jordan 1
PMCID: PMC1281707  PMID: 7535114

Abstract

We reinvestigate the dipolar chain model for an ion channel. Our goal is to account for the influence that ion-induced electrostriction of channel water has on the translocational energy barriers experienced by different ions in the channel. For this purpose, we refine our former model by relaxing the positional constraint on the ion and the water dipoles and by including Lennard-Jones contributions in addition to the electrostatic interactions. The positions of the ion and the waters are established by minimization of the free energy. As before, interaction with the external medium is described via the image forces. Application to alkali cations show that the short range interactions modulate the free energy profiles leading to a selectivity sequence for translocation. We study the influence of some structural parameters on this sequence and compare our theoretical predictions with observed results for gramicidin.

Full text

PDF

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Chiu S. W., Novotny J. A., Jakobsson E. The nature of ion and water barrier crossings in a simulated ion channel. Biophys J. 1993 Jan;64(1):98–109. doi: 10.1016/S0006-3495(93)81344-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. EISENMAN G. Cation selective glass electrodes and their mode of operation. Biophys J. 1962 Mar;2(2 Pt 2):259–323. doi: 10.1016/s0006-3495(62)86959-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Hille B., Schwarz W. Potassium channels as multi-ion single-file pores. J Gen Physiol. 1978 Oct;72(4):409–442. doi: 10.1085/jgp.72.4.409. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Jakobsson E., Chiu S. W. Stochastic theory of ion movement in channels with single-ion occupancy. Application to sodium permeation of gramicidin channels. Biophys J. 1987 Jul;52(1):33–45. doi: 10.1016/S0006-3495(87)83186-7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Jordan P. C., Bacquet R. J., McCammon J. A., Tran P. How electrolyte shielding influences the electrical potential in transmembrane ion channels. Biophys J. 1989 Jun;55(6):1041–1052. doi: 10.1016/S0006-3495(89)82903-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Jordan P. C. Ion-water and ion-polypeptide correlations in a gramicidin-like channel. A molecular dynamics study. Biophys J. 1990 Nov;58(5):1133–1156. doi: 10.1016/S0006-3495(90)82456-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Levitt D. G. Electrostatic calculations for an ion channel. I. Energy and potential profiles and interactions between ions. Biophys J. 1978 May;22(2):209–219. doi: 10.1016/S0006-3495(78)85485-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Levitt D. G. Interpretation of biological ion channel flux data--reaction-rate versus continuum theory. Annu Rev Biophys Biophys Chem. 1986;15:29–57. doi: 10.1146/annurev.bb.15.060186.000333. [DOI] [PubMed] [Google Scholar]
  9. Mackay D. H., Berens P. H., Wilson K. R., Hagler A. T. Structure and dynamics of ion transport through gramicidin A. Biophys J. 1984 Aug;46(2):229–248. doi: 10.1016/S0006-3495(84)84016-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Miller C. Bis-quaternary ammonium blockers as structural probes of the sarcoplasmic reticulum K+ channel. J Gen Physiol. 1982 May;79(5):869–891. doi: 10.1085/jgp.79.5.869. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Monoi H. Effective pore radius of the gramicidin channel. Electrostatic energies of ions calculated by a three-dielectric model. Biophys J. 1991 Apr;59(4):786–794. doi: 10.1016/S0006-3495(91)82291-3. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Partenskii M. B., Jordan P. C. Theoretical perspectives on ion-channel electrostatics: continuum and microscopic approaches. Q Rev Biophys. 1992 Nov;25(4):477–510. doi: 10.1017/s0033583500004388. [DOI] [PubMed] [Google Scholar]
  13. Roux B., Karplus M. Ion transport in a model gramicidin channel. Structure and thermodynamics. Biophys J. 1991 May;59(5):961–981. doi: 10.1016/S0006-3495(91)82311-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Sancho M., Martínez G. Electrostatic modeling of dipole-ion interactions in gramicidinlike channels. Biophys J. 1991 Jul;60(1):81–88. doi: 10.1016/S0006-3495(91)82032-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Skerra A., Brickmann J. Structure and dynamics of one-dimensional ionic solutions in biological transmembrane channels. Biophys J. 1987 Jun;51(6):969–976. doi: 10.1016/S0006-3495(87)83424-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Tredgold R. H., Hole P. N. Dielectric behaviour of dry synthetic polypeptides. Biochim Biophys Acta. 1976 Aug 4;443(1):137–142. doi: 10.1016/0005-2736(76)90497-1. [DOI] [PubMed] [Google Scholar]
  17. Urban B. W., Hladky S. B., Haydon D. A. Ion movements in gramicidin pores. An example of single-file transport. Biochim Biophys Acta. 1980 Nov 4;602(2):331–354. doi: 10.1016/0005-2736(80)90316-8. [DOI] [PubMed] [Google Scholar]
  18. Wallace B. A. Gramicidin channels and pores. Annu Rev Biophys Biophys Chem. 1990;19:127–157. doi: 10.1146/annurev.bb.19.060190.001015. [DOI] [PubMed] [Google Scholar]
  19. van Gunsteren W. F., Mark A. E. On the interpretation of biochemical data by molecular dynamics computer simulation. Eur J Biochem. 1992 Mar 15;204(3):947–961. doi: 10.1111/j.1432-1033.1992.tb16716.x. [DOI] [PubMed] [Google Scholar]

Articles from Biophysical Journal are provided here courtesy of The Biophysical Society

RESOURCES