Effects of concanavalin a on protein-C activity

Concanavaiin A interacts specifically with the oligosaccharides from protei n-C and modifies its anticoagulant activity. The lectin activates the prote in-C activity in a dose dependent manner as demonstrated by in vitro and in vivo assays. Concanavalin A at low concentration (0.1 to 2 mu g/ml) induce s an increase on the catalytic activity of protein-C; at higher concentrati ons (5 to 20 mu g/mL), the catalytic activity returns to the baseline. The effect of concanavalin A was prevented by incubating the protein-C with alp ha-methyl-mannoside or by treating the purified protein-C with alpha-mannos idase; furthermore, cleavage of mannosidic residues diminishes its catalyti c activity. Our results indicate that the oligomannosidic portion of protei n-C participates in the regulation of the catalytic activity of this protei n.