Synthesis of 5-thiomannose-containing oligomannoside mimics: binding abilities to concanavalin A

5-Thiomannose-containing oligomannoside mimics, 5SMan alpha(1,6)Man, 5SMan alpha(1,3)Man, 5SMan alpha(1,6)?Man alpha(1,3)Man?, Man alpha(1,6)?5SMan alpha(1,3)Man?, and 5SMan alpha(1,6)?5SMan alpha(1,3)Man?, were synthesized. Dissociation constants for the binding of these mimics to concanavalin A (ConA) were determined by a fluorescence anisotropy inhibition assay. Comparison of these data with those of the natural oligomannosides and with a crystal structure of the trimannoside-ConA complex established that replacing a ring oxygen atom with a sulfur atom causes about 1 kcal/mol decrease in the binding free energy when the ring oxygen is recognized with a hydrogen bonding.