[Effect of chemical modifiers on the antigen-binding capacity of antibodies].

The effect was followed up of the chemical modifications "carbamylation" and "benzylation" on the antigen-fixing activity of the foot-and-mouth disease immunoglobulins G and M. The chemical agents used - potassium cyanate and 2-hydroxi-5-nitrobenzylbromide--modified a considerable number of side lysine chains and tryptophane radicals, however, had no effect on the precipitation activity of the foot-and-mouth disease antibodies IgG and IgM manifested with the respective antigens. The lowered ability of the modified (to a higher degree) antibodies to form precipitations with the homologous virus was due to secondary reactions between the two components of the system, the functional groups of the active center remaining intact. The higher affinity of the IgM antibody to the homologous antigen was due to its polyvalent capacity (as compared to the bivalent immunoglobulin G).