VISCOELASTICITY OF BLM FROM CHOLINE PLASMALOGEN, ALKYLACYL-GLYCEROPHOSPHOCHOLINES AND DIACYL-GLYCEROPHOSPHOCHOLINES

Mechanical characteristics of bilayer lipid membranes (BLM) composed o f alkenylacyl-, alkylacyl-, and diacyl-glycerophosphocholines were stu died by measuring modulus of elasticity in the direction normal to BLM plane, E(perpendicular-to), and coefficient of dynamic viscosity eta. Alkenylacyl-glycerophosphocholine (choline plasmalogen) BLM typically show larger values of E(perpendicular-to) and eta as compared to thei r analogs, suggesting a tighter packing of their hydrophobic regions. Increasing cholesterol concentrations are associated with monotonicall y increasing values of parameters E(perpendicular-to) and eta of plasm alogen BLM, whereas a nonmonotonic dependence of these parameters with a maximum around c = 66 mol% cholesterol is typical for the diacyl an alog POPC. This may be due to the formation of cholesterol clusters at c > 66 mol%.