Hydration in lipid monolayers: Correlation of water activity and surface pressure

DISALVO, EDGARDO ANÍBAL; HOLLMANN, AXEL; MARTINI, M. FLORENCIA

Sub-Cellular Biochemistry

Springer

Lugar: New York; Año: 2015 vol. 71 p. 213 - 231

Abstract In order to give a physical meaning to each region of the membrane wedefine the interphase as the region in a lipid membrane corresponding to the polarhead groups imbibed in water with net different properties than the hydrocarbonregion and the water phase. The interphase region is analyzed under the scope ofthermodynamics of surface and solutions based on the definition of Defay-Prigogineof an interphase and the derivation that it has in the understanding of membraneprocesseses in the context of biological response. In the view of this approach,the complete monolayer is considered as the lipid layer one molecule thick plusthe bidimensional solution of the polar head groups inherent to it (the interphaseregion). Surface water activity appears as a common factor for the interactionof several aqueous soluble and surface active proteins with lipid membranes ofdifferent composition. Protein perturbation can be measured by changes in thesurface pressure of lipid monolayers at different initial water surface activities. Aspredicted by solution chemistry, the increase of surface pressure is independent ofthe particle nature that dissolves. Therefore, membranes give a similar response interms of the determined surface states given by water activity independent of theprotein or peptide.