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Ion transport across thin lipid membranes: a critical discussion of mechanisms in selected systems

Published online by Cambridge University Press:  17 March 2009

D. A. Haydon  and
S. B. Hladky
D. A. Haydon
Affiliation:
Physiological Laboratory, University of Cambridge, Downing Street, Cambridge
S. B. Hladky
Affiliation:
Physiological Laboratory, University of Cambridge, Downing Street, Cambridge
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Extract

There are now well-established examples of carriers and pores which facilitate the transfer of ions across thin lipid membranes. In the absence of such agents, lipid bilayer membranes are extremely impermeable to the common inorganic ions. Thus, the conductance of a pure lecithin + decane or glyceryl mono-oleate + decane membrane in M/10 NaCl is less than10−9Ω −1 cm−2. However, on the addition of small lipid-soluble molecules such as valinomycin, or surface-active polypeptides such as gramicidin A, the conductance may become so high (> 10−1 ω−l cm−2) that the resistance of the membrane merges into that of the aqueous phase. This review is concerned with the extent to which we now understand how these added substances transfer ions across lipid membranes. Attention has been concentrated on the simpler systems, i.e. the lipid-soluble ions, the 1–1 carriets, a simple pore and, with some loss of simplicity, a substance which prodeces interacting pores. Only molecules of known primary structure are discussed.

Type
Research Article
Information
Quarterly Reviews of Biophysics , Volume 5 , Issue 2 , May 1972 , pp. 187 - 282
Copyright
Copyright © Cambridge University Press 1972

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