Low Dielectric Permittivity of Water at the Membrane Interface: Effect on the Energy Coupling Mechanism in Biological Membranes

Cherepanov, Dmitry A.; Feniouk, Boris A.; Junge, Wolfgang; Mulkidjanian, Armen Y.

doi:10.1016/s0006-3495(03)74565-2

Cited by 150 publications

(143 citation statements)

References 61 publications

(90 reference statements)

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“…A relative enrichment in such stacks, as well as their stabilization by covalent linkages, could be driven by a number of factors, namely, the UV-resistance of polymerized and stacked Ssystems [112,164], the potential to utilize the energy of UV quanta for photopolymerization [11,12,196], the ability of Zn 2+ ions to catalyze the polymerization [197,198], and the low dielectric permittivity of the surface-adjoining water layers [199] that may have favoured condensation reactions. In addition, a regular mesh of electric charges at the ZnS surface, by attracting reactants and arranging them appropriately relative to each other, may have made the polymerization thermodynamically more favourable than in bulk water [124].…”

Section: First Settlers In the Zns Worldmentioning

confidence: 99%

Inorganic Polyphosphate Modulates TRPM8 Channels

Trimm¹

2011

Inorganic Chemistry

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Section: First Settlers In the Zns Worldmentioning

confidence: 99%

Inorganic Polyphosphate Modulates TRPM8 Channels

Trimm¹

2011

Inorganic Chemistry

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“…1C). Low capacitance necessitates a low value of myelin , which is promoted by the much lower dielectric constants of the lipid chains ( hc Ϸ 2) and proteins ( P ϭ 2.5-4.0) (6) compared with that of water ( w Ϸ 80 for bulk water and w Ϸ 40 for ''interfacial'' or ''partially trapped'' water in thin films) (7). Increasing the thickness of the myelin sheath increases R O /R I , and tighter membrane binding within the sheath decreases the water gaps, both of which decrease C myelin .…”

mentioning

confidence: 99%

Interaction forces and adhesion of supported myelin lipid bilayers modulated by myelin basic protein

Min

Kristiansen

Boggs

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

150

163

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Force-distance measurements between supported lipid bilayers mimicking the cytoplasmic surface of myelin at various surface coverages of myelin basic protein (MBP) indicate that maximum adhesion and minimum cytoplasmic spacing occur when each negative lipid in the membrane can bind to a positive arginine or lysine group on MBP. At the optimal lipid/protein ratio, additional attractive forces are provided by hydrophobic, van der Waals, and weak dipolar interactions between zwitterionic groups on the lipids and MBP. When MBP is depleted, the adhesion decreases and the cytoplasmic space swells; when MBP is in excess, the bilayers swell even more. Excess MBP forms a weak gel between the surfaces, which collapses on compression. The organization and proper functioning of myelin can be understood in terms of physical noncovalent forces that are optimized at a particular combination of both the amounts of and ratio between the charged lipids and MBP. Thus loss of adhesion, possibly contributing to demyelination, can be brought about by either an excess or deficit of MBP or anionic lipids.biomembrane adhesion ͉ lipid-protein interactions ͉ multiple sclerosis ͉ myelin membrane structure ͉ experimental allergic encephalomyelitis T he myelin sheath is a multilamellar membrane surrounding the axons of neurons in both the central nervous system (CNS) and peripheral nervous system (PNS) (1) as shown in Fig. 1 A and B. The myelin sheath consists of repeating units of double bilayers separated by 3-to 4-nm-thick aqueous layers that alternate between the cytoplasmic and extracellular faces of cell membranes (2) (Fig. 1C). Dehydrated myelin is unusual in that it is composed of 75-80% lipid and 20-25% protein by weight, compared with Ϸ50% of most other cell membranes (3) (Fig. 1 C and D). Multiple lipids make up the myelin sheath (Table 1), and each sheath, with its own distinct physical properties, contributes to the structure, adhesive stability, and possibly the pathogenesis of the myelin membrane. The asymmetric distribution of lipid composition on the cytoplasmic and extracellular faces likely also plays an important role (4). Myelin basic protein (MBP) constitutes 20-30% of total protein by weight and is located only between the 2 cytoplasmic faces, where it acts as an intermembrane adhesion protein.The myelin sheath acts as an electrical insulator, forming a capacitor surrounding the axon, which allows for faster and more efficient conduction of nerve impulses than unmyelinated nerves (5). According to cable theory, the time to transmit a signal over a distance x is ϭ 1 ⁄2RC myelin x 2 , where R is the resistance per unit length, and C myelin is the capacitance between the axon and its surroundings, which is given by (5) C myelin ϭ 2 0 myelin log͑R O /R I ͒ per unit length,where R O and R I are the outer and inner radii (Fig. 1B), 0 is the permittivity of free space, and the mean dielectric constant of the myelin sheath iswhere (Fig. 1C). Low capacitance necessitates a low value of myelin , which is promoted by the much l...

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“…(Of course, the H + s that make up the 'higher c H SL ' are the same ones that make up the Δψ, which is another objection to the pmf concept). Direct evidence for a separate outer fluid-membrane interface phase and an outer bulk fluid phase is provided by Cherepanov, Mulkidjanian, Junge and associates (Cherepanov et al, 2003;Cherepanov et al, 2004) (for a review, see Mulkidjanian et al, 2005). They used light + is held at the fluid membrane interface (SL) by electrostatic attraction to its gegenion.…”

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confidence: 99%

Voltage coupling of primary H+ V-ATPases to secondary Na+- or K+-dependent transporters

Harvey

2009

Journal of Experimental Biology

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SUMMARY This review provides alternatives to two well established theories regarding membrane energization by H+ V-ATPases. Firstly, we offer an alternative to the notion that the H+ V-ATPase establishes a protonmotive force (pmf) across the membrane into which it is inserted. The term pmf, which was introduced by Peter Mitchell in 1961 in his chemiosmotic hypothesis for the synthesis of ATP by H+ F-ATP synthases, has two parts, the electrical potential difference across the phosphorylating membrane, Δψ, and the pH difference between the bulk solutions on either side of the membrane, ΔpH. The ΔpH term implies three phases – a bulk fluid phase on the H+ input side, the membrane phase and a bulk fluid phase on the H+ output side. The Mitchell theory was applied to H+ V-ATPases largely by analogy with H+ F-ATP synthases operating in reverse as H+ F-ATPases. We suggest an alternative, voltage coupling model. Our model for V-ATPases is based on Douglas B. Kell's 1979 `electrodic view' of ATP synthases in which two phases are added to the Mitchell model – an unstirred layer on the input side and another one on the output side of the membrane. In addition, we replace the notion that H+ V-ATPases normally acidify the output bulk solution with the hypothesis, which we introduced in 1992, that the primary action of a H+ V-ATPase is to charge the membrane capacitance and impose a Δψ across the membrane; the translocated hydrogen ions (H+s) are retained at the outer fluid–membrane interface by electrostatic attraction to the anions that were left behind. All subsequent events, including establishing pH differences in the outside bulk solution, are secondary. Using the surface of an electrode as a model, Kell's`electrodic view' has five phases – the outer bulk fluid phase, an outer fluid–membrane interface, the membrane phase, an inner fluid–membrane interface and the inner bulk fluid phase. Light flash,H+ releasing and binding experiments and other evidence provide convincing support for Kell's electrodic view yet Mitchell's chemiosmotic theory is the one that is accepted by most bioenergetics experts today. First we discuss the interaction between H+ V-ATPase and the K+/2H+ antiporter that forms the caterpillar K+ pump, and use the Kell electrodic view to explain how the H+s at the outer fluid–membrane interface can drive two H+ from lumen to cell and one K+ from cell to lumen via the antiporter even though the pH in the bulk fluid of the lumen is highly alkaline. Exchange of outer bulk fluid K+ (or Na+) with outer interface H+ in conjunction with (K+ or Na+)/2H+ antiport, transforms the hydrogen ion electrochemical potential difference, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{{\mu}}_{\mathrm{H}}\) \end{document}, to a K+electrochemical potential difference, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{{\mu}}_{\mathrm{K}}\) \end{document} or a Na+electrochemical potential difference, \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{{\mu}}_{\mathrm{Na}}\) \end{document}. The \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{{\mu}}_{\mathrm{K}}\) \end{document} or \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\overline{{\mu}}_{\mathrm{Na}}\) \end{document} drives K+- or Na+-coupled nutrient amino acid transporters (NATs), such as KAAT1(K+ amino acid transporter 1), which moves Na+ and an amino acid into the cell with no H+s involved. Examples in which the voltage coupling model is used to interpret ion and amino acid transport in caterpillar and larval mosquito midgut are discussed.

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Low Dielectric Permittivity of Water at the Membrane Interface: Effect on the Energy Coupling Mechanism in Biological Membranes

Cited by 150 publications

References 61 publications

Inorganic Polyphosphate Modulates TRPM8 Channels

Inorganic Polyphosphate Modulates TRPM8 Channels

Interaction forces and adhesion of supported myelin lipid bilayers modulated by myelin basic protein

Voltage coupling of primary H+ V-ATPases to secondary Na+- or K+-dependent transporters

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