Effects of variation of ion and methylation of carrier on the rate constants of macrotetralide-mediated ion transport in lipid bilayers

1982 ◽  
Vol 68 (1) ◽  
pp. 191-206 ◽  
Author(s):  
Raynald Laprade ◽  
François Grenier ◽  
Jean-Yves Lapointe ◽  
Sylvic Asselin
Keyword(s):  
Ion Transport ◽  
Lipid Bilayers ◽  
Rate Constants

Carrier-mediated ion transport in lipid bilayer membranes

1984 ◽  
Vol 62 (8) ◽  
pp. 738-751 ◽  
Author(s):  
Raynald Laprade ◽  
François Grenier ◽  
Monique Pagé-Dansereau ◽  
Janine Dansereau
Keyword(s):  
Steady State ◽  
Ion Transport ◽  
Lipid Bilayers ◽  
Aqueous Phase ◽  
Rate Constants ◽  
The Other ◽  
Electrostatic Energy ◽  
Membrane Thickness ◽  
Lipid Bilayer Membranes ◽  
Electrical Measurements

The electrical properties predicted by a widely accepted model for carrier-mediated ion transport in lipid bilayers are described. The different steps leading to ion transport and their associated rate constants are reaction at the interface between an ion in the aqueous phase and a carrier in the membrane (kRi), followed by translocation of the ion–carrier complex across the membrane interior (kis) and its dissociation at the other interface (kDi) after which the free carrier crosses back the membrane interior (ks). Results on glyceryl monooleate (GMO) membranes for a family of homologue carriers, the macrotetralide actin antibiotics (nonactin, monactin, dinactin, trinactin, and tetranactin) and a variety of ions (Na+, Cs+, Rb+, K+, NH4+, and Tl+) are presented. Internally consistent data obtained from steady-state electrical measurements (zero-current potential and conductance, current-voltage relationship) allow us to obtain the equilibrium permeability ratios for the different ions and show that for a given carrier kRi is relatively invariant from one ion to the other, except for Tl+ (larger), which implies that the ionic selectivity is controlled by the dissociation of the complex. The values of the individual rate constants obtained from current relaxation experiments are also presented and confirm the findings from steady-state measurements, as well as the isostericity concept for complexes of different ions with the same carrier (kis invariant). These also allow us to determine the aqueous phase membrane and torus membrane partition coefficients. Finally, the observed increase in kis from nonactin to tetranactin and, for all homologues, from GMO–decane to solvent-free GMO membranes, together with the concomitant decrease in kDi, can be explained in terms of modifications of electrostatic energy profiles induced by variations in carrier size and membrane thickness.

scholarly journals Origins of Non-Selective Ion Transport across Lipid Bilayers

2012 ◽  
Vol 102 (3) ◽  
pp. 335a
Author(s):  
Igor Vorobyov ◽  
Roger Koeppe ◽  
Olaf S. Andersen ◽  
Toby W. Allen
Keyword(s):  
Ion Transport ◽  
Lipid Bilayers

Ion transport mediated by copolymers composed of polyoxyethylene and polyoxypropylene

1988 ◽  
Vol 254 (1) ◽  
pp. C20-C26 ◽  
Author(s):  
T. P. Atkinson ◽  
J. O. Bullock ◽  
T. F. Smith ◽  
R. E. Mullins ◽  
R. L. Hunter
Keyword(s):  
Ion Transport ◽  
Lipid Bilayers ◽  
Practical Interest ◽  
Water Soluble ◽  
Planar Lipid Bilayers ◽  
Monovalent Cations ◽  
Transport Activity ◽  
Experimental Systems ◽  
Surface Active Agents ◽  
Surface Active

Block copolymers composed of polyoxyethylene and polyoxypropylene were found to increase the influx of Na+ and the efflux of K+ from human erythrocytes. They were, however, ineffective at promoting the transport of Ca2+. The size of the ion fluxes induced by the copolymers correlated with their efficacy in stimulating inflammation. These compounds were also found to induce conductance increases in planar lipid bilayers in a nonvoltage dependent and nonstepwise manner. In both experimental systems, ion transport was facilitated only under temperature and ionic-strength conditions in which the polymers form aggregates in aqueous solution. In neither system did the concentration dependence of transport activity exhibit a pronounced cooperativity. These observations are consistent with the view that aqueous monomers of these surface active agents partition into the membrane, where they facilitate the conductive movement of monovalent cations by means of a carrier type mechanism. As a novel class of ionophores, these substances are of practical interest because they can be water soluble and are potentially reversible.

scholarly journals The Rate Constants of Valinomycin-Mediated Ion Transport through Thin Lipid Membranes

1971 ◽  
Vol 11 (12) ◽  
pp. 981-994 ◽  
Author(s):  
G. Stark ◽  
B. Ketterer ◽  
R. Benz ◽  
P. Läuger
Keyword(s):  
Ion Transport ◽  
Rate Constants ◽  
Lipid Membranes

scholarly journals Expression and characterization of the FXYD ion transport regulators for NMR structural studies in lipid micelles and lipid bilayers

2003 ◽  
Vol 1645 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Kevin J Crowell ◽  
Carla M Franzin ◽  
Anita Koltay ◽  
Sangmin Lee ◽  
Anna Maria Lucchese ◽  
...  
Keyword(s):  
Ion Transport ◽  
Lipid Bilayers ◽  
Structural Studies ◽  
Lipid Micelles

Water channel formation and ion transport in linear and branched lipid bilayers

2014 ◽  
Vol 16 (16) ◽  
pp. 7251-7262 ◽  
Author(s):  
Shihu Wang ◽  
Ronald G. Larson
Keyword(s):  
Ion Transport ◽  
Lipid Bilayer ◽  
Lipid Bilayers ◽  
Water Channel ◽  
Channel Formation ◽  
Bilayer Stability

The lipid bilayer stability and water channel morphologies are affected by the presence of methyl branches on lipid tails.

Impedance analysis of ion transport through gramicidin channels incorporated in solid supported lipid bilayers

1997 ◽  
Vol 42 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Claudia Steinem ◽  
Andreas Janshoff ◽  
Hans-Joachim Galla ◽  
Manfred Sieber
Keyword(s):  
Ion Transport ◽  
Lipid Bilayers ◽  
Impedance Analysis ◽  
Supported Lipid Bilayers

scholarly journals Equilibrium of Phosphointermediates of Sodium and Potassium Ion Transport Adenosine Triphosphatase

1997 ◽  
Vol 109 (5) ◽  
pp. 537-554 ◽  
Author(s):  
Kuniaki Suzuki ◽  
Robert L. Post
Keyword(s):  
Ion Transport ◽  
Rate Constants ◽  
Adenosine Triphosphatase ◽  
Reaction System ◽  
Potassium Ion ◽  
Hydrolysis Rate ◽  
Decay Kinetics ◽  
Potassium Ion Transport ◽  
Pool Model ◽  
Sodium And Potassium

Sodium and potassium ion transport adenosine triphosphatase accepts and donates a phosphate group in the course of its reaction sequence. The phosphorylated enzyme has two principal reactive states, E1P and E2P. E1P is formed reversibly from ATP in the presence of Na+ and is precursor to E2P, which equilibrates with Pi in the presence of K+. We studied equilibrium between these states at 4°C and the effect of Na+ on it. To optimize the reaction system we used a Hofmeister effect, replacing the usual anion, chloride, with a chaotropic anion, usually nitrate. We phosphorylated enzyme from canine kidney with [32P]ATP. We estimated interconversion rate constants for the reaction E1P ⇌ E2P and their ratio. To estimate rate constants we terminated phosphorylation and observed decay kinetics. We observed E1P or E2P selectively by adding K+ or ADP respectively. K+ dephosphorylates E2P leaving E1P as observable species; ADP dephosphorylates E1P leaving E2P as observable species. We fitted a 2-pool model comprising two reactive species or a twin 2-pool model, comprising a pair of independent 2-pool models, to the data and obtained interconversion and hydrolysis rate constants for each state. Replacing Na+ with Tris+ or lysine+ did not change the ratio of interconversion rate constants between E1P and E2P. Thus Na+ binds about equally strongly to E1P and E2P. This conclusion is consistent with a model of Pedemonte (1988. J. Theor. Biol. 134:165–182.). We found that Na+ affected another equilibrium, that of transphosphorylation between ATP·dephosphoenzyme and ADP·E1P. We used the reactions and model of Pickart and Jencks (1982. J. Biol. Chem. 257:5319–5322.) to generate and fit data. Decreasing the concentration of Na+ 10-fold shifted the equilibrium constant 10-fold favoring ADP·E1P over ATP·dephosphoenzyme. Thus Na+ can dissociate from E1P·Na3. Furthermore, we found two characteristics of Hofmeister effects on this enzyme.

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