Affinity electrophoretic determination of oligosaccharide specificity of Butea monosperma agglutinin

The oligosaccharide specificity of newly isolated Butea monosperma agglutinin (BMA) was determined by two-dimensional lectin affinity electrophoresis of alpha-fetoprotein (AFP) with concanavalin A, lentil lectin, erythroagglutinating phytohemagglutinin and Allomyrina dichotoma lectin, of which the specificities to known AFP oligosaccharides had been established. Effects of neuraminidase treatment on the reactivities of AFP to the lectins were also studied. The results indicated that BMA had the highest affinity for the exposed Gal residues of nonreducing termini of biantennary complex-type oligosaccharides, and that the affinity was reduced to zero in the following order by the presence of monosialyl residue of the Man alpha1->3 arm, monosialyl residue of the Man alpha1->6 arm, monosialyl residue of the Man alpha 1->3 arm and bisecting G1cNAc, and disialyl residues. BMA did not recognize Neu5Ac alpha2->6 and Neu5Ac alpha2->3 substitutions of Gal. These characteristics of BMA were shown to be useful in identifying malignancy-associated alteration of AFP sugar chains.