The binding of CTAB, a cationic surfactant, to the rat erythrocyte membrane

The adsorption of CTAB (cetyltrimethylammonium bromide) to the rat erythrocyte membrane was studied by determining the electrophoretic mobility of erythrocytes treated with CTAB and by SDS polyacrylamide electrophoresis of membrane proteins from erythrocytes treated with 14C-CTAB. At low concentrations of CTAB there was only a small reduction in the electrophoretic mobility of the erythrocytes. At lytic concentrations the electrophoretic mobility of the erythrocytes was markedly reduced. Alterations at the cell surface were found to be a more likely reason for the reduction in the electrophoretic mobility than interactions between the surfactant and charged groups at the cell surface. Very small amounts of radioactivity were found to be associated with the protein and sialoglycoprotein bands of the polyacrylamide gels. It is suggested that the adsorption of CTAB to the rat erythrocyte membrane does not involve electrostatic interactions between the surfactant and negatively charged groups of the sialoglycoproteins and that membrane proteins do not play a major role in the lytic events.