Modification of immunoglobulin G using specific reactivity of sugar moiety

A novel method for labeling immunoglobulin G by substitution of the sugar moiety with amino compounds is described. The method consists of mild treatment of IgG with sodium metaperiodate and subsequent Schiffs base formation of the product with amino compounds. Favourable conditions for the reaction were established. The method was sucessfully applied for the preparation of enzyme-labeled IgG antibody. Rabbit anti-(human IgG) labeled with peroxidase was used for the detection of human IgG and anti-Toxoplasma IgG by enzyme-linked immunoassay. Furthermore, substitution of oxidized IgG with acidic amino acid resulted in modification of the electric charge of IgG without affecting the antibody titre. Rabbit anti-(human IgG) labeled with aspartic acid was used for detecting antigenicity of human IgG by counter immunoelectrophoresis.