[Effect of bivalent cations on the temperature of phase transition in lipid membranes]

A theory is developed which explains the temperature shift of phase transition of bilayer delta Tc resulting from the interaction of charged polar heads of lipid molecules. It has been shown that adsorption of monovalent cations on the strongly charged membrane increases the transition temperature by about 15 degrees, this value being independent of the ionic strength and dielectric permeability epsilon of the medium. When divalent cations are adsorbed the temperature shift of transition is larger, the value delta Tc depending on medium epsilon, where the polar heads are located. If the membrane is in the electrolyte solution delta Tc approximately equal to 19 degrees; when a dehydrated contact with low dielectric permeability is initiated between the membranes, the transition temperature in this zone is to increase by about 160 degrees, which well agrees with the experimental data.