Characterization of sugar chain structures of human α‐fetoprotein by lectin affinity electrophoresis

Abstractα‐Fetoprotein (AFP) glycoforms, defined as AFP with different chemical structures of carbohydrate, were analyzed by affinity electrophoresis with several lectins of known specificities against complex‐type oligosaccharides. Serum AFP samples from cord blood on full‐term delivery and from patients with hepatocellular carcinoma and extrahepatic malignancies including gastrointestinal tumors and yolk sac tumors were used. Two‐dimensional lectin affinity electrophoresis and also lectin affinity chromatography coupled with lectin affinity electrophoresis were employed. More than ten AFP glycoforms were identified or characterized using the above‐mentioned AFP samples. Known specificities of the lectins against complex‐type oligosaccharides were refined or their additional specificities were found in this study. Lectin appeared to have specificity against carbohydrates by recognizing not only specific residues but also the whole carbohydrate molecule containing the residues, resulting in differential affinities for the lectin.