On the Coupling between Mechanical Properties and Electrostatics in Biological Membranes

GALASSI, VANESA VIVIANA; WILKE, NATALIA

Membranes

MDPI

Lugar: Basel; Año: 2021 vol. 11 p. 478 - 502

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.