Identification of alpha-fetoprotein-P4 sugar chain as alpha 2-->6 monosialylated biantennary complex-type oligosaccharides with an exposed galactose on the mannose alpha 1-->6 arm by two-dimensional extended agarose gel-lectin affinity electrophoresis.

Erythroagglutinating phytohemagglutinin (E-PHA)-reactive alpha-fetoprotein (AFP)-P4 and E-PHA weakly-reactive AFP-P3 of sera from cord blood at term and from patients with hepatocellular carcinomas showed a mobility of monosialo-AFP in two-dimensional extended agarose gel-E-PHA affinity electrophoresis. Asialo-AFP had as high an affinity for E-PHA as that of monosialo-AFP-P4, while disialo-AFP, AFP-P2, revealed a negligible affinity for E-PHA. For Allomyrina dichotoma lectin (allo A), asialo-AFP had no affinity with a mobility of AFP-A1s, monosialo-AFP-P4 had the highest affinity with a mobility of AFP-A3, and monosialo-AFP-P3 had an intermediate affinity with a mobility of AFP-A2s. The affinity of AFP-P4 for E-PHA was reduced by galactosidase digestion, indicating the presence of galactose residues, one sialylated and the other exposed.(ABSTRACT TRUNCATED AT 250 WORDS)