On the Coupling between Mechanical Properties and Electrostatics in Biological Membranes

Abstract

Cell membrane structure is proposed as a lipid matrix with embedded proteins, and thus, their emerging mechanical and electrostatic properties are commanded by lipid behavior and their interconnection with the included and absorbed proteins, cytoskeleton, extracellular matrix and ionic media. Structures formed by lipids are soft, dynamic and viscoelastic, and their properties depend on the lipid composition and on the general conditions, such as temperature, pH, ionic strength and electrostatic potentials. The dielectric constant of the apolar region of the lipid bilayer contrasts with that of the polar region, which also differs from the aqueous milieu, and these changes happen in the nanometer scale. Besides, an important percentage of the lipids are anionic, and the rest are dipoles or higher multipoles, and the polar regions are highly hydrated, with these water molecules forming an active part of the membrane. Therefore, electric fields (both, internal and external) affects membrane thickness, density, tension and curvature, and conversely, mechanical deformations modify membrane electrostatics. As a consequence, interfacial electrostatics appears as a highly important parameter, affecting the membrane properties in general and mechanical features in particular. In this review we focus on the electromechanical behavior of lipid and cell membranes, the physicochemical origin and the biological implications, with emphasis in signal propagation in nerve cells.

Free Energy Analyses of Cell-Penetrating Peptides Using the Weighted Ensemble Method

“…In our previous equilibrium simulation of Arg 9 with a DOPC/DOPG(4:1) membrane, we showed that electrostatic energy between Arg 9 and the membrane is strongly correlated with the penetration depth of Arg 9 [10]. This proved that electrostatic interaction between a CPP and a membrane is essential at the early translocation stage [26].…”

Surface Characterization of Lipid Biomimetic Systems

“…On the contrary, water accompanies the solute solubilizing in the membrane core and contributes to its stabilization. This process involves changes in membrane density due to expansion (area changes) and mechanical (bending and distortions) properties [4,5].…”

“…Ψs= Ψd e −Kδ (5) where ψ = surface potential at a distance δ of the Stern layer, ψd = surface potential at the Stern layer, κ = Debye-Hückel parameter that depends on the ionic strength, δ = distance, the interphase thickness. This layer is called the diffuse or outer Helmholtz layer and can be modified by the ionic strength (Figure 2) In general, the modification of this layer by changes in the surrounding media can affect the electric mobility of the particle.…”

“…The hydration of the lipids is determinant for the thermodynamic stability and structural dynamics and are a clue to understand the response of the membrane to environmental changes and biologically relevant bio-effectors (hydric and oxidative stress, hydrolytic enzymes, signal peptides, antioxidants). A recent model of lipid membranes includes explicitly the lipid-water interaction considering the membrane as composed by a bidimensional solution of hydrated polar head groups of phosphatidylcholines, named the interphase [1][2][3][4][5][6][7] (Figure 1). This model can be sustained in terms of the formalism of Thermodynamics of Irreversible Processes, in which the membrane is considered as an open system with respect to water exchange.…”

Surface Properties of Synaptosomes in the Presence of L-Glutamic and Kainic Acids: In Vitro Alteration of the ATPase and Acetylcholinesterase Activities

“…The physicochemical properties of biological membranes largely determine the functional activity of nerve cells during signal propagation [12]. The interfacial electrostatics are monitored as a highly important parameter in surface membrane properties.…”