COMPARATIVE-STUDY OF LANGMUIR MONOLAYERS OF IMMUNOGLOBULINS-G FORMED AT THE AIR-WATER INTERFACE AND COVALENTLY IMMOBILIZED ON SOLID SUPPORTS

Langmuir films of IgG formed at the air-water interface and covalently immobilized on solid supports were studied by means of fluorometry an d ellipsometry. Dependencies of monolayer molecular density and thickn ess on surface pressure were determined. The data obtained make possib le a model of the film molecular organization and its dependence on th e surface pressure. The films are of monomolecular layer character wit hin the entire range of achievable pressures on the air-water interfac e as well as on the solid supports. The molecular orientation changes with the pressure. In the monolayer on the air-water interface the mol ecules are positioned with their Fab-Fab-Fc ploane parallel to the sur face at pressures below 20 mN/m; when compressed up to 35 mN/m, they t urn by 90 degrees to reach perpendicular position with respect to the surface. Within the range 20 mN/m < pi < 35 mN/m the angle of molecula r inclination increases monotonically from 0 degrees to 90 degrees wit h pressure. The pattern of the orientation-pressure behavior for trans ferred monolayers is almost the same showing that the film molecular s tructure does not change upon deposition on to the solid activated sub strate.