Quantitation of physical-chemical properties of the aqueous phase inside the phoE ionic channel

Gutman, Menachem; Tsfadia, Yossi; Masad, Asnat; Nachliel, Esther

doi:10.1016/0005-2736(92)90077-y

Cited by 46 publications

(35 citation statements)

References 8 publications

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“…A similar distribution of charges is present in OmpF (Karshikoff et al, 1994) and in the evolutionary distant porins of Rhodobacter capsulatus (Weiss et al, 1991) and Rhodopseudomonas blastica (Kreusch et al, 1994). It has been postulated that these charges facilitate the diffusion of molecules through the pore (Gutman et al, 1992). Also a role in voltage gating has been suggested (Soares et al, 1995).…”

Section: *Corresponding Authormentioning

confidence: 84%

Voltage sensing in the PhoE and OmpF outer membrane porins of Escherichia coli: role of charged residues

Gelder

Saint

Phale

et al. 1997

Journal of Molecular Biology

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Section: *Corresponding Authormentioning

confidence: 84%

Voltage sensing in the PhoE and OmpF outer membrane porins of Escherichia coli: role of charged residues

Gelder

Saint

Phale

et al. 1997

Journal of Molecular Biology

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“…24 For porin-like channels, a water dielectric constant of 24 has been proposed. 26 More recent Brownian dynamics simulations, taking advantage of the MthK channel atomic structure, used values of e w ranging from 20 to 80 to show that the decrease of dielectric constant results in an increase of repulsive image forces that deepen the channel energy well. 27 Note that the use of a single, uniform value for the pore water dielectric constant means that the spatial dependence of e w is neglected.…”

Section: Introductionmentioning

confidence: 99%

Dielectric saturation of water in a membrane protein channel

Aguilella‐Arzo

Andrio

Aguilella

et al. 2009

Phys. Chem. Chem. Phys.

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Water molecules in confined geometries like nanopores and biological ion channels exhibit structural and dynamical properties very different from those found in free solution. Protein channels that open aqueous pores through biological membranes provide a complex spatial and electrostatic environment that decreases the translational and rotational mobility of water molecules, thus altering the effective dielectric constant of the pore water. By using the Booth equation, we study the effect of the large electric field created by ionizable residues of an hour-glass shaped channel, the bacterial porin OmpF, on the pore water dielectric constant, e w . We find a space-dependent significant reduction (down to 20) of e w that may explain some ad hoc assumptions about the dielectric constant of the protein and the water pore made to reconcile model calculations with measurements of permeation properties and pK a 's of protein residues. The electric potential calculations based on the OmpF protein atomic structure and the Booth field-dependent dielectric constant show that protein dielectric constants ca. 10 yield good agreement with molecular dynamics simulations as well as permeation experiments.

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“…The presence of dipoles at the vestibule, together with the cross-membranal electrostatic field facilitates the entry of ions into the channel. The second screening of the ions is made by the electrostatic potential inside the channel space which is amplified by the low dielectric constant of the water inside the channel (e intra-cavity ) [4][5][6]. Thus, the intensity of the electrostatic forces inside a small space is extremely sensitive to the value of the dielectric constant (e intra-cavity ).…”

Section: Introductionmentioning

confidence: 99%

“…The excitation of the pyranine to its first electronic singlet state [5] initiated a rapid ejecting proton, shifting the fluorescence emission of the dye from 435 nm (AOH*) to 515 nm (AO À *). The fluorescence decay curve of the AOH* species was reconstructed by a computer program of Agmon [9].…”

Section: Introductionmentioning

confidence: 99%