Molecular recognition. VIII. The binding of the β-D-galactopyranosyl residue of the Lewis b human blood group determinant by the lectin IV of Griffonia simplicifolia and by a monoclonal anti-Lewis b antibody. Evidence for intramolecular hydrogen bonding

The 3b-deoxy, 4b-deoxy, 6b-deoxy, 6b-deoxy-6b-fluoro, 6b-chloro-6b-deoxy, and the 5b-des-hydroxymethyl derivatives of the Lewis b (αLFucd(1 → 2)βDGalb(1 → 3)[αLFucc(1 → 4)]βDGlcNAca-OMe) human blood group determinant were synthesized in order to examine the involvement of the βDGal b unit in the binding of the Leb-OMe tetrasaccharide both by the lectin IV of Griffonia simplicifolia and a hybridoma monoclonal anti-Leb antibody. The replacement of the CH2OH-5b group by hydrogen resulted in very weak binding by both the proteins, but the 6b-deoxy derivative was bound nearly as strongly as the parent compound in the case of the lectin but nine times more strongly in the case of the antibody. The 6b-fluoride was slightly more strongly bound than the 6b-deoxy derivative by both the proteins. On the other hand, the 6b-chloride was bound three times more strongly by the lectin but three times more weakly by the antibody than the 6b-deoxy derivative. The thermodynamic parameters for the binding of the 6b-deoxy der...