Calorimetric study of the role of electrotatic interaction in the solubilization process of mimetic membranes by detergents

Abstract

Detergents are routinely used to solubilize the components of cell membranes, whose structural motif is given by the lipid phase. Therefore, the study of the physicochemical aspects of the detergent/lipid interaction is important both for a better understanding of the solubilization process and for the proposition of more efficient solubilization protocols. Most of these studies, however, are carried out with neutral lipids, even though biological membranes have a considerable percentage of anionic lipids. In addition, several detergents commonly used in solubilization protocols are ionic. From this, it is of great interest to understand and analyze the role of electrostatic interaction in the process of solubilization of membranes by detergents. In a previous project, we studied the process of solubilization of liposomes composed of neutral (phosphatidyl choline, PC) and anionic (phosphatidyl glycerol, PG) lipids by anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide, CTAB) and non-ionic (octylglucopyranoside, OG) using light scattering and optical microscopy techniques. In this project, we intend to study the same systems using two calorimetric techniques: isothermal titration calorimetry (ITC), in order to investigate the effect of electrostatic interaction on the partition of detergents into lipid bilayers of different charges, and differential scanning calorimetry (DSC), to investigate how the presence of detergents with different charges alters the gel-fluid phase transition profile of lipid bilayers of different compositions.