Binding kinetics of methyl alpha-D-mannopyranoside to concanavalin A: temperature-jump relaxation study with 4-methylumbelliferyl alpha-D-mannopyranoside as a fluorescence indicator ligand.

The binding of methyl alpha-D-mannopyranoside and methyl alpha-D-glucopyranoside to concanavalin A has been investigated by the temperature-jump relaxation kinetic technique using the competitive inhibitor 4-methylumbelliferyl alpha-D-mannopyranoside as an indicator of the binding reaction. The analysis shows that these saccharides bind to concanavalin A in a single bimolecular step. The binding parameters are compared to those of derivatized carbohydrates which have previously been used to study the binding of saccharides to concanavalin A. The similarity of the association rate constants indicates that a common process is involved in the binding of all carbohydrates to concanavalin A. The different affinities of saccharides for the lectin are primarily due to the different dissociation rate constants. A discussion of the proposed mechanism is given under the Appendix to clarify the fact that one of the observed relaxation times is faster than is possible with only the kinetic indicator reaction.