Modified blood group A trisaccharide probes: synthesis and interaction with antibodies.

Three derivatives modified at the acetamide fragment of blood group trisaccharide A, GalNAcalpha1-3(Fucalpha1-2)Galbeta-O-spacer were synthesised. In the first compound the amide oxygen was substituted for the sulfur atom. In the second compound the methyl group was replaced with the trifluoromethyl moiety, and in the third compound the methyl group was replaced with the hydrogen atom. The interaction of these probes with anti-A monoclonal antibodies gives the information about significance of trisaccharide methyl and carbonyl groups for the formation of protein-carbohydrates complex.