Time-resolved protonation dynamics of a black lipid membrane monitored by capacitative currents

Gutman, Menachem; Nachliel, Esther; Bamberg, Ernst; Christensen, B.

doi:10.1016/0005-2736(87)90468-8

Cited by 21 publications

(8 citation statements)

References 23 publications

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“…A direct method for studying the proton-protein dynamics is based on the Laser Induced Proton Pulse technique [18,[22][23][24]. In these studies, proteins were dissolved or suspended in a solution containing photoacid (photoacids are molecules whose pK a s are dramatically reduced when excited to their first electronic singlet state [25][26][27][28]).…”

Section: Introductionmentioning

confidence: 99%

Protein Surface Dynamics: Interaction with Water and Small Solutes

2005

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Abstract. Previous time resolved measurements had indicated that protons could propagate on the surface of a protein, or a membrane, by a special mechanism that enhances the shuttle of the proton towards a specific site [1]. It was proposed that a proper location of residues on the surface contributes to the proton shuttling function. In the present study, this notion was further investigated using molecular dynamics, with only the mobile charge replaced by Na + and Cl − ions. A molecular dynamics simulation of a small globular protein (the S6 of the bacterial ribosome) was carried out in the presence of explicit water molecules and four pairs of Na + and Cl − ions. A 10 ns simulation indicated that the ions and the protein's surface were in equilibrium, with rapid passage of the ions between the protein's surface and the bulk. Yet it was noted that, close to some domains, the ions extended their duration near the surface, suggesting that the local electrostatic potential prevented them from diffusing to the bulk. During the time frame in which the ions were detained next to the surface, they could rapidly shuttle between various attractor sites located under the electrostatic umbrella. Statistical analysis of molecular dynamics and electrostatic potential/entropy consideration indicated that the detainment state is an energetic compromise between attractive forces and entropy of dilution. The similarity between the motion of free ions next to a protein and the proton transfer on the protein's surface are discussed.

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Section: Introductionmentioning

confidence: 99%

Protein Surface Dynamics: Interaction with Water and Small Solutes

2005

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“…[61][62][63][64][65] The experimental system used for monitoring the reaction mechanism of monensin transport was a combination of the laser induced proton pulse and fast capacitive current measurements that follow a sub-ms protonation of the phospholipid membrane stretched over a small pore between compartments filled with conducting electrolyte solution. The proton forms a covalent bond with the carboxylate, while the cations fit into a crevice forms by six oxygen atoms none of them is of the single carboxylate of the ionophore.…”

Section: Visualization Of the Invisiblementioning

confidence: 99%

“…Yet, when the exchange is synchronized the electro-neutrality vanishes and the molecular events can be resolved and their rate constants are measurable. [61][62][63][64][65] The experimental system used for monitoring the reaction mechanism of monensin transport was a combination of the laser induced proton pulse and fast capacitive current measurements that follow a sub-ms protonation of the phospholipid membrane stretched over a small pore between compartments filled with conducting electrolyte solution. [64] To initiate the reaction, pyranine (FOH) was added to one compartment and consequently upon excitation, acidification of one face of the membrane occurred.…”

Section: Visualization Of the Invisiblementioning

confidence: 99%

The Privilege of Looking at the Molecular Details of Biochemical Reactions

Gutman

Nachliel

2017

Israel Journal of Chemistry

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The introducing the Laser‐Induced‐Proton‐Pulse (1979) allowed to monitor, at real time, the response of multi equilibria systems to pulse protonation. The reaction was initiated by the excitation of “photo acid” that releases a proton in the sub‐ns time‐scale, offsetting all acid base equilibria. This method was used to study the interaction of the protons with water, dyes, membranes, and proteins. The complexity of the systems increased from the most basic properties of dynamics up to mapping the structure of proton collecting antenna on protein surfaces, monitoring the chemical activity of water inside proteins, studying the electro‐neutral mechanism of proton ion exchange across bio‐membranes and charting the trajectories of ions inside ionic channels. The analysis of these systems led to deeper understanding of the physical chemical properties of micro‐environments like active sites and ionic channels, as well as a tool for advanced kinetic analysis of multi‐equilibria systems.

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“…The binding of pyranine to the surface is prevented by incorporation of Phosphatidyl serine in the membranes (Clement and Gould, 1981;Gutman et al, 1987). At a mole fraction of 10% the PS density on the surface is sufficient to prevent the adsorption of the dye, yet not too high to increase the separation distance to very large values.…”

Section: Proton-pyranine Recombination Between Negatively Charged Memmentioning

confidence: 99%

Dynamic studies of proton diffusion in mesoscopic heterogeneous matrix

Gutman

Nachliel

Kiryati

1992

Biophysical Journal

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The thin water layer, as found in chloroplast or mitochondria, is confined between low dielectric amphypathic surfaces a few nm apart.The physical properties of this mesoscopic space, and how its dimensions affect the rate of chemical reactions proceeding in it, is the subject for this study.The method selected for this purpose is time resolved fluorometry which can monitor the reversible dissociation of a proton from excited molecule of pyranine (8 hydroxy pyrene 1,3,6 tri sulfonate) trapped in thin water layers of a multilamellar vesicle made of neutral or slightly charged phospholipids.The results were analyzed by a computer program of N. Agmon (Pines, E., D. Huppert, and N. Agmon. 1988. J. Am. Chem. Soc. 88:5620-5630) that simulates the diffusion of a proton, subjected to electrostatic attraction, in a thin water layer enclosed between low affinity, proton binding surfaces. The analysis determines the diffusion coefficient of the proton, the effective dielectric constant of the water and the water accessibility of the phosphomoieties of the lipids.These parameters were measured for various lipids [egg-phosphatidylcholine (egg PC), dipalmitoyl phosphatidylcholine (DPPC), cholesterol + DPPC (1:1) and egg PC plus phosphatidyl serine (9:1)] and under varying osmotic pressure which reduces the width of the water layer down to approximately 10 approximately across.WE FOUND THAT: (a) The effective dielectric constant of the aqueous layer, depending on the lipid composition, is approximately 40. (b) The diffusion coefficient of the proton in the thin layer (30-10 approximately across) is that measured in bulk water D = 9.3 10(-5) cm(2)/s, indicating that the water retains its normal liquid state even on contact with the membrane. (c) The reactivity of the phosphomoiety, quantitated by rate of its reaction with proton, diminishes under lateral pressure which reduces the surface area per lipid.We find no evidence for abnormal dynamics of proton transfer at the lipid water interface which, by any mechanism, accelerates its diffusion.

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Time-resolved protonation dynamics of a black lipid membrane monitored by capacitative currents

Cited by 21 publications

References 23 publications

Protein Surface Dynamics: Interaction with Water and Small Solutes

Protein Surface Dynamics: Interaction with Water and Small Solutes

The Privilege of Looking at the Molecular Details of Biochemical Reactions

Dynamic studies of proton diffusion in mesoscopic heterogeneous matrix

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