Effect of polymerized silicic acid on mixed lipid-protein monolayers used as cell-membrane models II. Pepsin-sphingomyelin films

Abstract

Mixed pepsin-sphingomyelin films exhibit behavior typical of bidimensional systems whose components are miscible in all proportions. The non-polar chains of their components are believed to establish weak hydrophobic interactions. The dynamic compression-expansion II-A curves obtained in the presence of polysilicic acid differ from those recorded in its absence, which may arise from an ionic interaction whereby silicate ions accommodate themselves among the film molecules and bind strongly to the sphingomyelin molecules to form a rigid surface network in which the protein molecules are trapped.