Assembly and structural study of the films of immunoglobulin M on solid substrates

Immunoglobulin M (IgM) was immobilized from a solution by the method of cha rge self-assembly on solid substrates (ordered polyelectrolytes and as-clea ved mica). The process of film formation and the structural organization wa s controlled and studied by the methods of atomic-force microscopy and X-ra y reflectometry. It was shown that adsorption from rather concentrated (0.6 80-0.068 mg/ml) IgM solutions gave rise to formation of 100- to 150-Angstro m -thick continuous protein layers. At lower concentrations (0.006 mg/ml), no continuous protein films were formed. The substrates of mica-type atomic ally smooth surfaces provide a higher image resolution, which, in turn, all ows the observation of isolated IgM molecules and their aggregates. In the image plane, the molecules have rounded contours 300-500 Angstrom in diamet er and 40-60 Angstrom in height. (C) 2000 MAIK "Nauka/Interperiodica".