Valinomycin as a probe for the study of structural changes of black lipid membranes

Stark, G.; Benz, Roland; Pohl, G.; Janko, K.

doi:10.1016/0005-2736(72)90357-4

Cited by 76 publications

(24 citation statements)

References 18 publications

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“…Table 3 shows a more or less pronounced dependence of the experimental quantities z, v, ~ and 9 on the chain length. The analysis revealed a strong increase of kR with decreasing chain length of the lipid molecules (Table 4) and thus confirms and extends a previous study, which was only based on stationary experiments (Stark et aL, 1972). It remains an open question whether the effect on kR is produced by the action of the membrane structure on valinomycin itself or on the access of ions to the place of complex formation.…”

Section: The Rate Constants Of Ion Transportsupporting

confidence: 89%

“…Above this limit large deviations occur which might reflect the approximative treatment of the energy barrier, but could as well be produced by structural changes of the membrane at high voltages. They could be caused by the pressure exerted by the charged membrane capacity (Stark, Benz, Pohl & Janko, 1972). For ko< kMs the current-voltage curve becomes sublinear, as the complexes at the negative interface do not dissociate fast enough.…”

Section: The Rate Constants Of Ion Transportmentioning

confidence: 99%

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Valinomycin-mediated ion transport through neutral lipid membranes: Influence of hydrocarbon chain length and temperature

et al. 1973

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Summary. Stationary electrical conductance experiments together with nonstationary relaxation experiments allow a quantitative determination of rate constants describing carrier-mediated ion transport. Valinomycin-induced ion transport across neutral lipid membranes was studied. The dependence of the transport parameters on the chain length of the lipid molecules, on the kind of alkali ion, and on the temperature was determined. The relaxation time 9 of the current following a voltage jump shows a marked increase with decreasing temperature or with increasing chain length of the lipid molecules. This variation of v is interpreted on the basis of a varying membrane fluidity. It is shown that under favorable circumstances the equilibrium constant of complex formation in the aqueous phase may be obtained from membrane experiments. Furthermore, the kinetics of exchange of valinomycin between membrane and water was studied. We found a marked influence of the toms surrounding the black film on the kinetics as well as on the total amount of valinomycin molecules in the membrane.

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Section: The Rate Constants Of Ion Transportsupporting

confidence: 89%

Section: The Rate Constants Of Ion Transportmentioning

confidence: 99%

Valinomycin-mediated ion transport through neutral lipid membranes: Influence of hydrocarbon chain length and temperature

et al. 1973

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“…8, gives an activation energy, AG*, which is about 17 kcal/mol below 71 ~ C. Stark et al [33] have found, for a dierucoyllecithin bilayer, in the presence of valinomycin, A G*= 17 kcal/mol, a value within the same range. If we consider the temperature-induced change in the fluidity coefficient of a saturated paraffinic or naphthenic mineral oil [30], we find an activation energy which is of the same order of magnitude (8 to 13 kcal/mol).…”

Section: Conductance-temperature Behavior In the Presence Of Valinomycinmentioning

confidence: 90%

Monolayer black membranes from bipolar lipids of archaebacteria and their temperature-induced structural changes

et al. 1983

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The membrane of Caldariella acidophila, an extreme thermophilic archaebacterium, is characterized by unusual bipolar complex lipids. They consist of two nonequivalent polar heads, linked by a C40 alkylic component. The molecular organization of these lipids in the plasma membrane is still a matter of study. In this paper, we present current-voltage measurements on artificial bipolar lipid membranes, indicating that molecules are indeed organized as a covalently bound bilayer, in which each molecule is completely stretched and spans its entire thickness. Furthermore, conformational transitions of these artificial membranes (which could be formed only above 70 degrees C from a lipid/squalene dispersion) are analyzed in the 80 to 15 degrees C temperature range. Abrupt variations in capacitance and valinomycin-induced conductance seem to indicate the occurrence of at least two structural changes. Measurements are also extended to different solvent systems. Results are consistent with the picture of a monolayer bipolar lipid membrane in which few solvent molecules align themselves parallel to the lipophilic chains. The amount of solvent as well as the temperature at which conformational transitions occur, depend on the solvent system in which the lipid is dispersed.

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“…Fettiplace, Andrews and Haydon (1971) have determined on the basis of capacitance measurements that membranes formed using shorter chain solvents, such as the n-decane employed here, retain a significant amount of solvent after thinning to the black state. Stark, Benz, Pohl, and Janko (1972) have measured bilayer membrane capacitance as a function of hydrocarbon chain length of the lipid used, and have also concluded that solvent content of the membranes is significant. We therefore suspect that residual solvent makes a major contribution to the barrier to the translocation of DpA-, particularly for the shorter 16 and 18 carbon chain lipids.…”

Section: Effects Of Hydrocarbon Compositionmentioning

confidence: 99%

The interaction of hydrophobic ions with lipid bilayer membranes

Bruner

1975

J. Membrain Biol.

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Electrical relaxation studies have been made on lecithin bilayer membranes of varying chain length and degree of unsaturation, in the presence of dipicrylamine. Results obtained are generally consistent with a model for the transport of hydrophobic ions previously proposed by Ketterer, Neumcke, and Läuger (J. Membrane Biol. 5:225, 1971). This medel visualizes as three distinct steps the interfacial absorption, translocation, and desorption of ions. Measurements at high electric field yield directly the density of ions absorbed to the membrane-solution interface. Variation of temperature has permitted determination of activation enthalpies for the translocation step which are consistent with the assumption of an electrostatic barrier in the hydrocarbon core of the membrane. The change of enthalpy upon absorption of ions is, however, found to be negligible, the process being driven instead by an increase of entropy. It is suggested that this increase may be due to the destruction, upon absorption, of a highly ordered water structure which surrounds the hydrophic ion in the aqueous phase. Finally, it is shown that a decrease of transient membrane conductance observed at high concentration of hydrophobic ions, previously interpreted in terms of interfacial saturation, must instead by attributed to a more complex effect equivalent to a reduction of membrane fluidity.

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Valinomycin as a probe for the study of structural changes of black lipid membranes

Cited by 76 publications

References 18 publications

Valinomycin-mediated ion transport through neutral lipid membranes: Influence of hydrocarbon chain length and temperature

Valinomycin-mediated ion transport through neutral lipid membranes: Influence of hydrocarbon chain length and temperature

Monolayer black membranes from bipolar lipids of archaebacteria and their temperature-induced structural changes

The interaction of hydrophobic ions with lipid bilayer membranes

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