4-O-(α-D-Galactopyranosyl)-D-galactose

4-O-(α-D-Galactopyranosyl)-D-galactose is a specific ligand that binds to receptors of uropathogenic E. coli and Shigella dysenteriae toxin. In addition, 4-O-(α-D-Galactopyranosyl)-D-galactose defines the P blood group system. These studies conducted with E. coli that express class I and class II PapG adhesins indicate that 4-O-(α-D-Galactopyranosyl)-D-galactose inhibits hemagglutination of human erythrocytes. Furthermore, the class I adhesins are more potently effected when there is a substitution on the aromatic ring at the O-1 and the O-3′ positions.