TY - JOUR
T1 - Lithium-selective permeation through lipid bilayer membranes mediated by a di-imide ionophore with nonsymmetrical imide substituents (ETH1810)
AU - Zeevi, Amira
AU - Margalit, Rimona
PY - 1991/4
Y1 - 1991/4
N2 - 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.
AB - 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.
KW - biogenic amines
KW - ion transport
KW - ionic selectivity
KW - ionophore
KW - lipid bilayers
KW - lithium
UR - http://www.scopus.com/inward/record.url?scp=0025755559&partnerID=8YFLogxK
U2 - 10.1007/BF01870528
DO - 10.1007/BF01870528
M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???
C2 - 1652642
AN - SCOPUS:0025755559
SN - 0022-2631
VL - 121
SP - 133
EP - 140
JO - Journal of Membrane Biology
JF - Journal of Membrane Biology
IS - 2
ER -