The Kinetics of Carbohydrate Binding to Concanavalin A

The kinetics and equilibrium of binding of the chromophoric sugar derivative p-nitrophenyl-α-d-mannopyranoside to concanavalin A at pH 6.95 have been studied. The association rate constant for the chromophoric sugar-concanavalin A complex is 8 x 104 m-1 s-1 and the dissociation rate constant is 4 s-1 at 20°. The dissociation constant measured directly by difference spectroscopy at 316 nm is 4.09 ± 0.62 x 10-5 m compared to 5 x 10-5 m calculated from the kinetic constants. The equilibrium results are approximately the same as those reported earlier by Hassing and Goldstein ((1970) Eur. J. Biochem. 16, 549). The results are consistent with a simple association-dissociation scheme with independent sugar binding sites.