MIXED MONOLAYERS AND BILAYERS OF PHOSPHOLIPIDS WITH POLY-GAMMA-METHYL-L-GLUTAMATE IN ALPHA-HELICES - RHEOLOGICAL AND ELECTRICAL BEHAVIOR

The rheological properties of pure and mixed monomolecular films and the electrical behavior of mixed bilayers, black lipid membranes (BLM), Of L-alpha-dipalmitoylphosphatidylcholine (DPPC), L-alpha-dioleoylphosphatidylcholine (DOPC), cholesterol (CHOL) and poly-gamma-methyl-L-glutamate in alpha-helical conformation (PGMG) have been studied. The interfacial viscosity of the pure components and of the binary and ternary mixtures DOPC/PGMG, DPPC/PGMG, DPPC/CHOL, DPPC/PGMG/CHOL and DOPC/PGMG/CHOL were measured at the water-air interface. Resistances, capacitances and current-voltage measurements for DOPC/CHOL and DOPC/PGMG/CHOL BLMs are also reported. The monolayer study demonstrates that the surface viscosity of DPPC/PGMG mixtures is close to that of PGMG, while for the DOPC/PGMG system the viscosity is in between that of the pure components. Further it is shown that cholesterol strongly decreases the interfacial viscosity of DPPC and, to a lesser extent, of DPPC/PGMG mixtures. The electrical properties of the BLMs show that PGMG interacts with the DOPC/CHOL membrane by changing the membrane hydration.