The Electrostatic Properties of Membranes

McLaughlin, Stuart

doi:10.1146/annurev.bb.18.060189.000553

Cited by 1,013 publications

(607 citation statements)

References 10 publications

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“…To get a rough estimate of the distance between the reactive cysteine and a surface charge, we used the following equation (McLaughlin 1989; Elinder and Århem 1999): \documentclass[10pt]{article} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{pmc} \usepackage[Euler]{upgreek} \pagestyle{empty} \oddsidemargin -1.0in \begin{document} \begin{equation*}{\mathrm{{\psi}}}_{{\mathrm{r}}}={2e\;{\mathrm{exp}} \left \left(-{\mathrm{{\kappa}}}r\right) \right }/{ \left \left(4{\mathrm{{\pi}{\epsilon}}}_{0}{\mathrm{{\epsilon}}}_{r}r\right) \right }{\mathrm{,}}\end{equation*}\end{document} where ψ r is the potential at a distance r from an elementary charge e , assuming that the charge is located at the border between a low dielectric (membrane) and a high dielectric (water, ɛ r = 80) medium. κ is the inverse of the Debye length in the aqueous phase (9.8 Å in the 1-K solution; see Elinder and Århem 1999 for calculation).…”

Section: Methodsmentioning

confidence: 99%

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Elinder

Männikkö

Larsson

2001

The Journal of General Physiology

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Voltage-gated ion channels respond to changes in the transmembrane voltage by opening or closing their ion conducting pore. The positively charged fourth transmembrane segment (S4) has been identified as the main voltage sensor, but the mechanisms of coupling between the voltage sensor and the gates are still unknown. Obtaining information about the location and the exact motion of S4 is an important step toward an understanding of these coupling mechanisms. In previous studies we have shown that the extracellular end of S4 is located close to segment 5 (S5). The purpose of the present study is to estimate the location of S4 charges in both resting and activated states. We measured the modification rates by differently charged methanethiosulfonate regents of two residues in the extracellular end of S5 in the Shaker K channel (418C and 419C). When S4 moves to its activated state, the modification rate by the negatively charged sodium (2-sulfonatoethyl) methanethiosulfonate (MTSES−) increases significantly more than the modification rate by the positively charged [2-(trimethylammonium)ethyl] methanethiosulfonate, bromide (MTSET+). This indicates that the positive S4 charges are moving close to 418C and 419C in S5 during activation. Neutralization of the most external charge of S4 (R362), shows that R362 in its activated state electrostatically affects the environment at 418C by 19 mV. In contrast, R362 in its resting state has no effect on 418C. This suggests that, during activation of the channel, R362 moves from a position far away (>20 Å) to a position close (8 Å) to 418C. Despite its close approach to E418, a residue shown to be important in slow inactivation, R362 has no effect on slow inactivation or the recovery from slow inactivation. This refutes previous models for slow inactivation with an electrostatic S4-to-gate coupling. Instead, we propose a model with an allosteric mechanism for the S4-to-gate coupling.

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Section: Methodsmentioning

confidence: 99%

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Elinder

Männikkö

Larsson

2001

The Journal of General Physiology

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“…Instead, ions can interact with the bilayer and modify its structural, interfacial, and electrostatic properties. Experiments have shown that anionic 4, [22][23][24][25] and cationic 26,27 membranes interact readily with their counterions (especially divalent ones), whereas the interactions of zwitterionic lipid bilayers with salt ions appear rather sensitive to the size and valency of ions. [28][29][30][31][32][33][34][35][36][37][38][39][40][41] As for molecular-level computational studies, the increase in computing power in the past few years has made it possible to extend computer simulations beyond the relatively long relaxation times of tens to hundreds of nanoseconds required for equilibration of ions in lipid/water systems.…”

Section: Introductionmentioning

confidence: 99%

Ion Dynamics in Cationic Lipid Bilayer Systems in Saline Solutions

et al. 2009

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Positively charged lipid bilayer systems are a promising class of nonviral vectors for safe and efficient gene and drug delivery. Detailed understanding of these systems is therefore not only of fundamental but also of practical biomedical interest. Here, we study bilayers comprising a binary mixture of cationic dimyristoyltrimethylammoniumpropane (DMTAP) and zwitterionic (neutral) dimyristoylphosphatidylcholine (DMPC) lipids. Using atomistic molecular dynamics simulations, we address the effects of bilayer composition (cationic to zwitterionic lipid fraction) and of NaCl electrolyte concentration on the dynamical properties of these cationic lipid bilayer systems. We find that, despite the fact that DMPCs form complexes via Na + ions that bind to the lipid carbonyl oxygens, NaCl concentration has a rather minute effect on lipid diffusion. We also find the dynamics of Cl -and Na + ions at the water-membrane interface to differ qualitatively. Cl -ions have well-defined characteristic residence times of nanosecond scale. In contrast, the binding of Na + ions to the carbonyl region appears to lack a characteristic time scale, as the residence time distributions displayed power-law features. As to lateral dynamics, the diffusion of Na + ions within the water-membrane interface consists of two qualitatively different modes of motion: very slow diffusion when ions are bound to DMPC, punctuated by fast rapid jumps when detached from the lipids. Overall, the prolonged dynamics of the Na + ions are concluded to be interesting for the physics of the whole membrane, especially considering its interaction dynamics with charged macromolecular surfaces.

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“…The electrostatic interfacial potential generated at the membrane/ solution interface due to the membrane charge plays a crucial role in a variety of membrane-associated phenomena, including the activity of membrane proteins and receptors, ion binding and transport, ligand recognition, and interaction with other membranes (McLaughlin 1989). It is well established that electrostatic interaction plays a crucial role in stabilizing lipidprotein interactions in membranes and in the process of membrane binding of proteins and peptides (McLaughlin 1989;McLaughlin and Aderem 1995). In addition, electrostatic forces are important in determining the transmembrane orientation and topology of membrane-spanning a-helices of integral membrane proteins (von Heijne 1992).…”

Section: Introductionmentioning

confidence: 99%

Effect of micellar charge on the conformation and dynamics of melittin

Raghuraman

Chattopadhyay

2004

Eur Biophys J

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Electrostatic interactions play a crucial role in modulating and stabilizing molecular interactions in membranes and membrane-mimetic systems such as micelles. We have monitored the change in the conformation and dynamics of the cationic hemolytic peptide melittin bound to micelles of various charge types, utilizing fluorescence and circular dichroism (CD) spectroscopy. The sole tryptophan of melittin displays a red-edge excitation shift (REES) of 3-6 nm when bound to anionic, nonionic, and zwitterionic micelles. This suggests that melittin is localized in a restricted environment, probably in the interfacial region of the micelles, and this region offers considerable restriction to the reorientational motion of the solvent dipoles around the excited state tryptophan in melittin. Further, the rotational mobility of melittin is considerably reduced in these micelles and is found to be dependent on the surface charge of micelles. Interestingly, our results show that melittin does not partition into cetyltrimethylammonium bromide (CTAB) micelles owing to electrostatic repulsion between melittin and CTAB micelles, both of which carry a positive charge. In addition, the fluorescence lifetime of melittin is modulated in micelles of different charge types. The lowest mean fluorescence lifetime is observed in the case of melittin bound to anionic sodium dodecyl sulfate (SDS) micelles. CD spectroscopy shows that micelles induce significant helicity to melittin, with maximum helicity being induced in the case of melittin bound to SDS micelles. Fluorescence quenching measurements using the neutral aqueous quencher acrylamide show differential accessibility of melittin in various types of micelles. Taken together, our results show that micellar surface charge can modulate the conformation and dynamics of melittin. These results could be relevant to understanding the role of the surface charge of membranes in the interaction of membrane-active, amphiphilic peptides with membranes.

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The Electrostatic Properties of Membranes

Cited by 1,013 publications

References 10 publications

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

S4 Charges Move Close to Residues in the Pore Domain during Activation in a K Channel

Ion Dynamics in Cationic Lipid Bilayer Systems in Saline Solutions

Effect of micellar charge on the conformation and dynamics of melittin

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