Surface studies on a new poly-amino-acid

Abstract

A newly synthesized polypeptide, poly-1:1:2: lysine-glutamicacid-leucine has been studied in monomolecular films. In many respects it behaves analogously to natural proteins, as is to be expected from its composition. The controversial issues concerning the interfacial dissociation of proteins are examined by comparison with results from this poly-amino-acid. By an improvement of technique to reach the requisite low pressures, it is shown that dissociation of the polymer at the interfaces air/10 -2 N acid and oil/water does not occur; the effects apparently suggesting such dissociation are entirely due to variations in the type of quasi-lattice of the interface. Statistical equations of the Flory and Huggins types, based on a two dimensional quasi-lattice theory, are tested using the copolymer; the sites in the surface are shown to be occupied in a non-random manner. The complete surface equation of state for charged macromolecules is derived, including intermolecular and intramolecular electrical repulsion.