DEPOSITION, MOLECULAR ORGANIZATION AND FUNCTIONAL ACTIVITY OF IgG LANGMUIR FILMS A.Tronin1, T.Dubrovsky2 1-Institute of Crystallography, Leninsky 59, Moscow 117333, Russia 2-Bakh Institute of Biochemistry, Leninsky 33, Moscow 117071, Russia
Monolayers formed at the air-water interface and covalently immobilized on solid supports were studied by means of ellipsometry, time resolved fluorimetry, nanogravimetry and immunology testing. The model of the film molecular packing has been put forward, according to which the molecular orientation depends on the surface pressure. At the pressure below 20 mN/m the molecules are oriented parallel to the surface, when compressed up to 35 mN/m the molecules take perpendicular position, with their Fab fragments oriented preferentially outside the film. Within the range 20 mN/m<<35 mN/m the molecular inclination angle increases monotonically from 0 to 90. The pattern of the orientation-pressure behavior for transferred monolayers is almost the same showing that the film molecular structure does not change upon deposition onto the solid activated substrate. Complex structures of protein A sublayer-Langmuir film of IgG have been obtained and studied as well. The problem of protein monolayer stability has been addressed, and partial unfolding of the protein globule has been suggested to be an origin for high molecular surface activity. The dependence of immunological activity of IgG films on the packing parameters has been studied.
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