A series of monosaccharide (46), disaccharide (3,712), and trisaccharide (1315) analogs of the native ligand 2, which fills the binding site of monoclonal antibody Se 155.4, have been synthesized and their bioactivity measured by solid- and solution-phase assays. The syntheses of disaccharide analogs sought to replace galactose by various alkyl groups at the O-2 position of mannose. The activity of one of these O-2 alkyl analogs was 75% of that observed for the trisaccharide and points to only weak net bonding between the solvent exposed galactose residue and the antibody binding site. The synthesis of talose analogs 13 and 14, where the mannose or galactose residues of 2 were replaced by talose produced ligands with activities from one-third to one-half of that seen for the native ligand 2. These activity changes did not exhibit discernable correlations with the ability of talose to disrupt water of solvation.Key words: abequose, 3,6-dideoxy-D-xylo-hexose, talose disaccharide and trisaccharide, antibody oligosaccharide interactions, molecular recognition of carbohydrates, water in antibody complexes, Salmonella LPS, monoclonal antibody Se 155.4, bacterial O-antigen.
Disaccharides 1-3 corresponding to the antigenic determinants of Salmonella serotypes A, B, and D1were synthesized in a form suited for use in biosensors. The disaccharide determinants each contain a unique 3,6-dideoxyhexose, namely abequose (3,6-dideoxy-D-xylo-hexose), paratose (3,6-dideoxy-D-ribohexose), and tyvelose (3,6-dideoxy-D-arabino-hexose), are α-linked to the 3-position of D-mannopyranose. The disaccharides were further derivatized with a linear aglycon that has a terminal amino group, and can be readily coupled to pertinent chains carrying a terminal thiol for the construction of self-assembled monolayers (SAMs). Efficient routes that employed a single 3,6-dideoxygenation step were developed for the synthesis of paratoside 15 and tyveloside 22.Key words: Salmonella O-antigens, lipopolysaccharide, abequose, paratose, tyvelose, 3,6-dideoxyhexose, deoxygenation, glycoside tethers, immobilization via pentenyl glycosides.