Lithium-selective permeation through lipid bilayer membranes mediated by a di-imide ionophore with nonsymmetrical imide substituents (ETH1810)

Amira Zeevi*, Rimona Margalit

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

The neutral, noncyclic Li--selective ionophore ETH1810, which is a di-imide, differs structurally from previous similar ionophores by removal of the intramolecular symmetry of the N-imide substituents. Properties of this ionophore, as a potential carrier of lithium, were probed through studies of ionophore-induced changes in electrical properties of lipid bilayer membranes. ETH1810 was found capable of transporting lithium and other monovalent cations, across lipid bilayer membranes, forming 2:1 ionophore: ion membrane-permeating species. It was found to be 10-fold more potent than ETH1644, which was the previous best ionophore of this type. The selectivity sequence among alkali cations was found to be: Li+(1)>Na+ (0,009)>K+ (0.004)>Cs+(0.0035). Among the physiological alkali cations, it constitutes a 40 (vs. Na+) to 160% (vs. K+) improvement over ETH1644. ETH1810 was also found to be capable of acting as a carrier of biogenic amines and related molecules, with the following selectivity sequence: tryptamine (20)>phenylethylamine (7.8)>tyramine (4.3)>serotonin (2.5)>Li+ (1)>NH4+ (0.013)>dopamine (0.012). It was found that protons, at physiological concentrations, do not interfere with the lithium transport mediated by ETH1810. The relationship between the improvements in ionic selectivity and potency vs. the differences in structural features is discussed.

Original languageEnglish
Pages (from-to)133-140
Number of pages8
JournalJournal of Membrane Biology
Volume121
Issue number2
DOIs
StatePublished - Apr 1991

Keywords

  • biogenic amines
  • ion transport
  • ionic selectivity
  • ionophore
  • lipid bilayers
  • lithium

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