Interactions of concanavalin A with α- d-glucans

Abstract

The interaction of α- d-glucans with Concanavalin A has been studied by turbidimetry. Amylopectins from various botanical sources and two glycogens were characterised for their fine structure [% (1→6)-α-linkages, % beta-amylolysis, iodine interaction] and their molecular size (intrinsic viscosity, gel permeation). Branched α- d-glucans with defined structures were prepared either by enzymic (beta-amylolysis or phosphorolysis of oyster glycogen and amylopectins) or mild acid hydrolysis of waxy-maize amylopectin. Selection of high concentrations of Con A (>0.9 mg/mL) and (20m m, Tris-HCl) buffer allow high sensitivity for studying the interactions. Two structural features of branched polysaccharides are demonstrated to be major parameters for the interaction, namely, the hydrodynamic volume and the external chain-length. At pH 7.0, the Con A interaction modifies the beta-amylolysis kinetics by decreasing the affinity constant of beta-amylase, whereas no modification was detected at pH 5.2.