The chemistry of carcinoembryonic antigen.

The structure of carcinoembryonic antigen is being determined as an approach to greater diagnostic specificity in the radioimmune assay. Examination by combined gas chromatography-mass spectrometry of derivatized saccharides from CEA has given a general outline of its carbohydrate structure. Sialic acid and fucose were completely destroyed, and galactose and mannose were partially destroyed by a single periodate treatment. Serial periodate oxidation (Smith degradation) destroyed additional amounts of galactose and mannose, as well as significant amounts of N-acetylglucosamine. Antigenic activity persisted, indicating that the residues destroyed played little, if any, part in the antigenicity of DEA.