Purification and properties of blood-group-specific lectins from Vicia cracca

The lectins from the seeds of Vicia cracca react specifically with human blood group A erythrocytes. They were purified by affinity chromatography on an adsorbent containing matrix-bound N-acyl-D-galactosamine. By a continuous pH gradient the lectins could be separated into two fractions each of which was shown to consist of several agglutinating species. The behaviour of both fractions in affinity chromatography was paralleled by the pH dependence of the interaction with the hapten sugar N-acetyl-D-galactosamine. Both lectin fractions have the same molecular (125000) and subunit (33000) weights, display the same pH dependence of their titre against A1 erythrocytes, and bind to N-acetyl-D-galactosamine at pH 8 with the same constant of about 6 X 10(3)M-1.