ABSTRACT
Immunoglobulins are proteins found, among other locations, in the blood serum of birds and mammals. Many immunoglobulins, however, will recognize their antigens even when the antigenic protein is no longer in its native structure. Crystallographic molecular models of complexes between immunoglobulins raised against synthetic peptides and the peptides themselves heighten these concerns. Immunodiffusion is a more sophisticated procedure for permitting antigen and immunoglobulin to diffuse into each other. An immunoprecipitate is held together by a complex collection of interfaces formed between the binding sites on the tips of the Fab arms of the various immunoglobulins present in antiserum and their respective epitopes on the molecules of antigen. Immunostaining of immunoblots is also used to identify which polypeptides are components of a particular covalent complex produced by cross-linking. Immunoglobulins can also be used to isolate a particular protein by immunoadsorption.
