Physical chemical properties if lipid membrane interphases: new and all paradigms

DISALVO, E. A.; ROSA, A.S; CEJAS, J; PÉREZ, H.A.; FRÍAS, M.A; PINTO, A.O

San Luis

Conferencia; VIII Encuentro de Física y Química de Superficies; 2018

Universidad de San Luis

Lipids organized as a bilayer constitute the structural backbone of biological membranes. From a mechanical, thermodynamic and electrochemical behaviour it is considered a peculiar material that cannot be mimicked by other materials1.However, the studies of these systems from the physical chemistry and thermodynamic point of view are usually interpreted along laws and formalisms applicable to tridimensional macroscopic systems and the deviation are mostly explained by introducing geometrical arrangements and structures that are controversial.A critical point in the failure of classical paradigms is that they consider the membrane a solubility (partition) disregarding the interphasial phenomena. Although water is considered to be the solvent by which lipids stabilize as a bilayer due to entropic and energetic contributions, it is not considered as a structural component that determines the response of the bilayer as a surface thermodynamic system2.In this work, the failures of the old paradigms are discussed and a new approach within the frame of thermodynamics of irreversible process3 is applied to the bilayer as an open system with the ability to exchange water with the surroundings that explains the responses of the membranes to perturbations by biologically significant effectors4. The approach is valid to explain surface pressure /area isotherms and swelling and shrinkage processes in monolayers and bilayers, respectively and the link between them.The thermodynamic picture is corroborated by changes in membrane structure at mesoscopic and microscopic level by studies in FTIR and fluorescence spectroscopy, surface pressure isotherms and kinetics.Referencias1. Evans, E. A., and R. Skalak, 1980. Mechanics and Thermodynamics of Biomembranes. CRC Press, Inc., Boca Raton, FL.2. Disalvo, E. A., Hollmann A, Semorile L. & Martini M.F. 2013, Evaluation of the Defay-Prigogine model for the membrane interphase in relation to biological response in membrane-protein interactions. Biochim. Biophys. Acta (BBA)-Biomembranes, 1828, 1834?1839.3. Katchalsky, A. & Curran, P. Non Equilibrium Thermodynamics in Biophysics, Harvard University Press, Cambridge, MA, 1965.4. R. Defay, I. Prigogine (1966) Surface Tension and Adsorption, John Wiley & Sons: New York.