EN
This paper studies the influence of equimolar mixtures of biologically-active cationic and anionic amphiphiles (dodecyl-oxymethylene-methyl-morpholinium chloride (DOMM) and one of the series of sodium alkylsulphonates (ASJ with n = 1,2,4,6,8,10,12 and 14 carbon atoms in the alkyl chain) on calcium ion desorption from lecithin liposome membranes. It was shown that by choosing the hydrophobic part of the amphiphilic anion in the mixture one can regulate the efficiency of the amphiphilic cation towards the desorption process. The rate constant of that process strongly depends on the surfactant concentration. The differences in the effectiveness of the different compounds are most distinct at lower concentrations and vanish when the concentration increases. The results are discussed in response to the amphiphilic ion-pair hydrophobicity and their electrical properties. The role of the hypothetical, temporal complexes consisting of the alkylsulphonate anion(s) and calcium cation (ASn-Ca)+ in the calcium ion exchange is discussed. The mechanism of Ca2+ desorption from the surface of the phospholipid bilayer under the simultaneous action of the cationic and anionic detergents is proposed. According to our proposal calcium ion release occurs due to the joint action of the monovalent cationic and anionic detergents in coincidence with a divalent calcium ion. To authenticate the proposed mechanisms of calcium ion release, the shapes of the experimental curves were compared with the theoretical ones obtained by computer simulation using the cellular automata method.