PURE AND MIXED MONOLAYERS OF POLY-L-METHIONINE AND POLY-GAMMA-METHYL-L-GLUTAMATE WITH 1,2 "DIOLEYL-L-ALPHA-PHOSPHATIDYLCHOLINE AT AIR-WATER-INTERFACE

Data are presented which show that monolayers of poly-L-methionine (PM) and poly- gamma -methyl-L-glutamate (PMG), spread at an air-water interface, exhibit a high compressibility plateau region at 10 dyn/cm and 18 dyn/cm in their respective pi -A curves. This behavior is related to a alpha -helical conformation of the polypeptide molecules in the said interface. Comparative studies of the areas per residue observed in the spreading isotherms, with the areas calculated from molecular models, indicate that the polypeptide molecules should be associated in parallel, forming islets of at least 5 alpha -helix chains. Mixed monolayers corresponding to the poly-L-methionine (PM)-1,2 dioleyl-L- alpha -phosphatidylcholine (DOPC) and poly- gamma -methyl-L-glutamate (PMG)-1,2 dioleyl-L- alpha -phosphatidylcholine (DOPC) systems, follow, in every case, the additivity rule for monolayer composition, any indicating that its components are insoluble in the surface mixture.