Kinetic analysis of calcium binding to concanavalin A

The kinetics of calcium binding to concanavalin A was studied utilizing ultraviolet difference spectral measurements. The results show that calcium binds to the lectin in a biphasic process: a rapid and reversible phase, followed by a relaxation phase with a k_obs of 0.012 sec^?1. Kinetic measurements were used to calculate the association constant, K_a, for calcium binding to concanavalin A of 2.7 x 10⁴ M^?1, in reasonable agreement with values obtained by equilibrium methods.