Protein–carbohydrate interaction. XV. The role of bivalent cations in concanavalin A – polysaccharide interaction

Abstract

Extensive dialysis of concanavalin A solution against 1.0 M acetic acid results in the loss of its ability to precipitate specific polysaccharides. This activity is restored upon the addition of bivalent cations such as Mg2+, Mn2+, Ca2+, Co2+, and Zn2+. An optimum range of the cation concentration is observed for the activation of metal-free concanavalin A. High concentrations of bivalent cations (> 0.05 M) are inhibitory to the interaction of concanavalin A with specific polysaccharides. Of all the metals tested, Mn2+ appears to be bound most strongly. Urea and guanidine-HCl cause the inhibition of polysaccharide-precipitating activity of concanavalin A, probably by virtue of their unfolding effect on the protein structure.