title: Structure of hydrated immunoglobulins and antigen-antibody complexes. Electron microscopy of spray-freeze-etched specimens.
abstract: The structure of spray-frozen IgG and IgM, either free in solution or specifically bound to bacterial flagella is compared after freeze-etching with the corresponding preparations negatively stained. The freeze-etched IgG is readily detected; most of the hydrated particles appear approximately spherical with an average diameter of about 12 nm. About 20% are triangular with sides of about 13-14 nm. Antibodies attached to flagella are clearly seen on the top as well as the exposed edges. The technique can thus be used for antigen localization on freeze-etched macromolecules and also on the surface of larger structures. The dimensions and shape of freeze-etched bound IgM confirm the earlier interpretations of the structure of this antibody based on negative staining.
mesh_terms: D000936:Antigen-Antibody Complex / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism; D005613:Freeze Etching / Q000379:methods; D007074:Immunoglobulin G / Q000378:metabolism*; D007075:Immunoglobulin M / Q000378:metabolism*; D008854:Microscopy, Electron; D011485:Protein Binding; D012482:Salmonella paratyphi A / Q000378:metabolism
chemical_list: D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D007075:Immunoglobulin M