Haptens antigen-binding site

The antigen-binding site binds haptens in crevices and protein antigens on large flat surfaces... 

Information concerning the binding site of antibodies has recently been obtained from the X-ray studies (Amzel et aL, 1974 Segal et aL, 1974). Both the human myeloma NEW and the mouse myeloma IgA McPC603 are known to bind haptens. In both cases the antigen-binding site is at the end of the Fab fragment exposed to solvent and formed by... 

The most common of these systems is the enzyme-multiplied immunoassay technique or EMIT, which is particularly suited to the measurement of small molecules (haptens) such as drugs. EMIT is a trade mark of the Syva Corporation of Palo Alto, California. Although it does not involve the separation of bound fraction from free it is nevertheless a competitive assay system. The antigen is labelled with an enzyme in such a way that the enzyme retains its catalytic activity. When the antigen binds to the antibody the enzyme becomes inhibited, probably by an induced conformational change or by steric hindrance of the enzyme active site (Figure 7.15). 

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