Effect of polyelectrolytes on the rheological properties of lipid monolayers.

C. I. CÁMARA; N. WILKE

Sierra de la Ventana - Buenos Aires

Congreso; Sociedad Argentina de Biofísica. XLIII Reunión Anual 2014; 2014

Sociedad Argentina de Biofísica

Glycosaminoglycans (GAGs) are important constituents of the extracellular matrix of microorganisms, animals and plants. They are large polymers formed by mono, di or oligosaccharides bounded by glycosidic linkages and may have a variety of functional groups along their chains. Some biological functions have been associated to the presence of polysaccharides in the extracellular matrix, however, their specific role is not known. It has been reported that its presence affects the dynamics of lipids and proteins and therefore, the aim of this work was to study how the presence of different polysaccharides modifies the rheological properties of model membranes.We studied the effect of the presence of different polysacarides on lipid monolayers of dimyristoyl phosphatidyl glycerol (DMPG) and dipalmitoyl phosphatidyl choline (DPPC). The polysacharides were dextran sulfate of high (DSA) and low (DSB) sulphate content, and di-ethyl-amino-ethyl dextran (DEAE). Both dextrane sulphates are negatively charged while DEAE is a cationic polymer. Both lipid monolayers were prepared on subphases composed of CaCl2 (10 mM) and NaCl (145mm) at 24±1ºC. Under these conditions both lipids show a phase transition from liquid expanded to liquid condensed phase (at about 15mN/m for DMPG and 7,5 mN/m for DPPC). When the monolayers were formed in the presence of DSB, no change in the isotherms or in the surface viscosity was observed. For DSA, the effect on the film depends of the lipid while in the presence of DEAE the expanded phase of the lipids resulted stabilized and the viscosity changed.