Concanavalin A affinity immunoelectrophoresis of slowly migrating glycoproteins by chemical charge modification

A method for the study of slowly migrating glycoproteins by lectin-affinity immunoelectrophoresis is described. The principle of the method is to modify chemically the polypeptide part of the glycoprotein in question to increase the net negative charge of the molecule without affecting the carbohydrate parts. In a model experiment, desialylated human alpha 1-acid glycoprotein is modified and it is shown by lectin affinity immunoelectrophoresis that glycan-bound sialic acid does not influence the binding of human alpha 1-acid glycoprotein to concanavalin A. Additionally, the method is used to study the carbohydrate-based microheterogeneity of slowly migrating mouse serum glycoproteins, and hitherto undetected microheterogeneity inherent in mouse transferrin and mouse haemopexin is detected and described in normal and inflammatory mice.