Carbohydrate binding specificity and purification by biospecific affinity chromatography of Ascidia malaca Traust. hemagglutinins

The carbohydrate specificities of Ascidia malaca serum hemagglutinins were determined by hemagglutination inhibition tests. Analysis of agglutinins against rabbit and human A, B, O erythrocytes suggests that the size of the combining site corresponds to a disaccharide with a specificity for saccharides containing a D-galacto configuration (D-melibiose, D-raffinose, D-galactose, alpha-lactose, lactulose, L-arabinose). No anomeric specificity was observed with oligosaccharides. Hydroxyl groups probably involved in hydrogen-bond formation with agglutinin binding site, were identified as carbons C2, C4, C5 and C6 of D-galactose. Absorption experiments showed that two distinct agglutinins with similar sugar specificity ranges were responsible for rabbit and human erythrocyte agglutination. The D-galactose specificity of the agglutinins allowed the isolation, by biospecific affinity chromatography of the serum, of a protein fraction demonstrated by polyacrylamide gel electrophoresis.