Molecular interaction in monolayers II—The action of haemolytic and agglutinating agents on lipo-protein monolayers

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Abstract
All lytic agents penetrate cholesterol films, and, with the exception of saponin, disperse protein films. Cholesterol forms weakly-associated complexes with gliadin. On gradual compression, the film first sets to a gel, then liquefies, and finally shows only the characteristics of a simple cholesterol film, the protein being squeezed out of the complex to form a monolayer below the cholesterol. At pH''s more acid than the isoelectric point of cholesterol, no gelatin of the mixed film occurs, so that the protein-cholesterol combination differs on opposite sides of this isoelectric point. Previous exps. have shown that soaps disperse a protein film, saponin penetrates it without dispersion. The penetration of saponin is facilitated by combination of the protein with cholesterol. The lytic action of saponin on red blood cells is thus probably due to penetration of lipoid or lipoid-protein constituents of the membrane. In films formed by interaction of polar groups only, i.e., the type of film formed by proteins with agglutinating or sensitizing agents, polymerization of the non-protein constituent prevents dispersal by Na-oleate. Agglutinating agents such as tannic acid may be considered to act by the production of a relatively hydrophobic tannic acid-cell wall protein system. Sensitizing agents such as Janus green are adsorbed by proteins, but because of their non-polymerization do not prevent dispersal of the resultant film by Na-oleate. The sensitizing action of the antibody globulin is considered to be due to the formation of a sheath of denatured protein about the cell with which lysins in the serum will combine.

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