PROCAINE PENETRATION INTO MIXED MONOMOLECULAR FILMS OF CHOLESTEROL AND DIPALMITOYLPHOSPHATIDYLCHOLINE

Penetration of procaine into cholesterol and mixed cholesterol-dipalmi toylphosphatidylcholine monolayers is studied by recording surface pre ssure vs. mean molecular area curves for cholesterol and mixed c chole sterol-dipalmitoylphoshatidylcholine (molar ratio 1 : 1) monolayers sp read onto a aqueous procaine solutions of different concentrations. Th e amount of procaine in the interface is derived by means of Gibbs' eq uation. Penetration of procaine is much less than found earlier in the case of pure dipalmitoylphosphatidylcholine monolayers. Results are d iscussed in terms of molecular structure.