Preparation of monovalent succinyl-concanavalin A and its mitogenic activity

Monovalent succinyl-concanavalin A was prepared by photoaffinity labeling of succinyl-concanavalin A with p-azidophenyl a-D-mannopyranoside. This concanavalin A derivate showed a weak but definite mitogenic acitivity against mouse splenic lymphocytes and human peripheral lymphocytes, suggesting that direct receptor cross-linkage on the cell surface is not an obligatory prerequisite for the activation of lymphocytes.

Photoaffinity labeling of concanavalin A. Preparation of a concanavalin A derivative with reduced valence

Concanavalin A (Con A) was labeled with p-azidophenyl alpha-D-mannopyranoside under ultraviolet irradiation and the reaction products were separated by affinity chromatography on Sephadex G-100 at pH 5. One of the Con A derivatives thus obtained was characterized as a monovalent dimer at pH 5 and a divalent tetramer at pH 7 by sedimentation equilibrium and equilibrium dialysis, indicating that this photoaffinity labeling did not alter the quaternary structure of Con A. In agreement with these results, the labeled Con A did not show the capacity to precipitate glycogen at pH 5, but it formed precipitates with glycogen at pH 7. Although its hemagglutinating activity was found to be weaker than that of the native Con A, the dose-response cure of the labeled Con A in the mitogenic stimulation of human peripheral lymphocytes was almost identical to that of the native con A.