Capture of potassium ions by valinomycin: a molecular dynamics simulation study

Forester, Timothy R.; Smith, Walter J.; Clarke, J. H. R.

doi:10.1021/j100039a033

Cited by 13 publications

(17 citation statements)

References 5 publications

(7 reference statements)

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“…Thus, considering the application of DE and the resulting sinusoidal responses of current and concentrations and dDci dt ¼ jxDc i Eqs. (15) and (16) can be rewritten as jx…”

Section: Impedance Spectroscopy Analysismentioning

confidence: 99%

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EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

Vallejo

Gervasi

2007

Journal of Electroanalytical Chemistry

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“…Thus, considering the application of DE and the resulting sinusoidal responses of current and concentrations and dDci dt ¼ jxDc i Eqs. (15) and (16) can be rewritten as jx…”

Section: Impedance Spectroscopy Analysismentioning

confidence: 99%

“…As a cation carrier for potassium transport across cell membranes, valinomycin is of considerable biological importance [15]. It is a cyclodepsipeptide, cyclo(L-Val-D-Hyl-D-Val-LLac) 3 that contains a single 36-member ring.…”

Section: Introductionmentioning

confidence: 99%

EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

Vallejo

Gervasi

2007

Journal of Electroanalytical Chemistry

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“…The MD methods adopted in this study are closely related to those in our previous work on the VM and K+-VM systems Forester et al, 1995). Four simulations were undertaken, each at a temperature of 310 K and 300 ps in length, including a period of 50 ps for initial equilibration of the system.…”

Section: Computational Methodology Molecular Dynamics Simulationsmentioning

confidence: 99%

“…Lennard Jones solvent has recently been successfully used to represent a biological membrane (Guba and Kessler, 1994;Roux et al, 1995). In our previous work an adapted AMBER force field (Weiner et al, 1986) was employed to model both K+-VM and VM in the solid state and in vacuo ; in addition it was used to model the spontaneous capture of partially solvated K+ (Forester et al, 1995). The same adapted AMBER force field was used here also.…”

Section: Computational Methodology Molecular Dynamics Simulationsmentioning

confidence: 99%

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Molecular dynamics simulations of valinomycin and its potassium complex in homogeneous solvents

Forester¹,

Smith²,

Clarke³

1996

Biophysical Journal

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Molecular dynamics simulations of kalinomycin (VM) and its potassium complex in water and in a Lennard Jones solvent are reported. In agreement with experimental evidence the structure of K(+)-VM in nonpolar solution is similar to the solid state structure whereas the structure of uncomplexed VM is not. In water uncomplexed VM retains the Lac and HyV faces (which are lost in nonpolar solution) and shows some similarity with the solid-state structure obtained by crystallization from dimethyl sulfoxide (DMSO). However, also in agreement with spectroscopic data a dynamic equilibrium between a set of conformers is established in both solvents. Our model reproduces the experimental dipole moment (3.6 D) of VM in nonpolar solution. We also observed the spontaneous decomplexation of K(+)-VM in water, with the ion passing through the HyV face in preference to the Lac face. Water attack was observed through both faces. The time scale for all conformational transitions is of the order of 100 ps, with structural changes associated with the (de)-complexation reaction controlled by the ring dihedrals in the vicinity of the L-lactic acid residues. Global structural functions, radial distribution functions, and VM ring dihedral analysis are presented, along with an analysis of the decomplexation event.

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Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

2007

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Kinetics of facilitated ion transport through planar bilayer membranes are normally analyzed by electrical conductance methods. The additional use of electrical relaxation techniques, such as voltage jump, is necessary to evaluate individual rate constants. Although electrochemical impedance spectroscopy is recognized as the most powerful of the available electric relaxation techniques, it has rarely been used in connection with these kinetic studies. According to the new approach presented in this work, three steps were followed. First, a kinetic model was proposed that has the distinct quality of being general, i.e., it properly describes both carrier and channel mechanisms of ion transport. Second, the state equations for steady-state and for impedance experiments were derived, exhibiting the input-output representation pertaining to the model's structure. With the application of a method based on the similarity transformation approach, it was possible to check that the proposed mechanism is distinguishable, i.e., no other model with a different structure exhibits the same input-output behavior for any input as the original. Additionally, the method allowed us to check whether the proposed model is globally identifiable (i.e., whether there is a single set of fit parameters for the model) when analyzed in terms of its impedance response. Thus, our model does not represent a theoretical interpretation of the experimental impedance but rather constitutes the prerequisite to select this type of experiment in order to obtain optimal kinetic identification of the system. Finally, impedance measurements were performed and the results were fitted to the proposed theoretical model in order to obtain the kinetic parameters of the system. The successful application of this approach is exemplified with results obtained for valinomycin-K(+) in lipid bilayers supported onto gold substrates, i.e., an arrangement capable of emulating biological membranes.

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Capture of potassium ions by valinomycin: a molecular dynamics simulation study

Cited by 13 publications

References 5 publications

EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

EIS studies of valinomycin-mediated K+ transport through supported lipid bilayers

Molecular dynamics simulations of valinomycin and its potassium complex in homogeneous solvents

Impedance Analysis of Ion Transport Through Supported Lipid Membranes Doped with Ionophores: A New Kinetic Approach

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