Water permeability of gramicidin A-treated lipid bilayer membranes

P. A. Rosenberg, A. Finkelstein

Research output: Contribution to journalArticle

93 Citations (Scopus)

Abstract

In membranes containing aqueous pores (channels), the osmotic water permeability coefficient, P(f), is greater than the diffusive water permeability coefficient, P(d). In fact, the magnitude of P(f)/P(d) is commonly used to determine pore radius. Although, for membranes studied to date, P(f)/P(d) monotonically declines with decreasing pore radius, there is controversy over the value it theoretically assumes when that radius is so small that water molecules cannot overtake one another within the channel (single-file transport). In one view it should equal 1, and in another view it should equal N, the number of water molecules in the pore. Gramicidin A forms, in lipid bilayer membranes, narrow aqueous channels through which single-file transport may occur. For these channels it is found that P(f)/P(d) approximately = 5. In contrast, for the wider nystatin and amphotericin B pores, P(f)/P(d) approximately = 3. These findings offer experimental support for the view that P(f)/P(d) = N for single-file transport, and it is therefore concluded that there are approximately five water molecules in a gramicidin A channel. A similar conclusion was reached independently from streaming potential data. Using single-channel conductance data, the authors calculated the water permeability of an individual gramicidin A channel. In the Appendix the authors report that there is a wide range of channel sizes and lifetimes in cholesterol-containing membranes.

Original languageEnglish (US)
Pages (from-to)341-350
Number of pages10
JournalJournal of General Physiology
Volume72
Issue number3
StatePublished - 1978

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Gramicidin
Lipid Bilayers
Permeability
Membranes
Water
Nystatin
Aquaporins
Amphotericin B
Cholesterol

ASJC Scopus subject areas

  • Physiology

Cite this

Rosenberg, P. A., & Finkelstein, A. (1978). Water permeability of gramicidin A-treated lipid bilayer membranes. Journal of General Physiology, 72(3), 341-350.

Water permeability of gramicidin A-treated lipid bilayer membranes. / Rosenberg, P. A.; Finkelstein, A.

In: Journal of General Physiology, Vol. 72, No. 3, 1978, p. 341-350.

Research output: Contribution to journalArticle

Rosenberg, PA & Finkelstein, A 1978, 'Water permeability of gramicidin A-treated lipid bilayer membranes', Journal of General Physiology, vol. 72, no. 3, pp. 341-350.
Rosenberg, P. A. ; Finkelstein, A. / Water permeability of gramicidin A-treated lipid bilayer membranes. In: Journal of General Physiology. 1978 ; Vol. 72, No. 3. pp. 341-350.
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