Interaction of synthetic glycopeptides carrying clusters ofO-glycosidic disaccharide chains (β-d-Gal(1–3)-α-d-GalNAc) withβ-d-galactose-binding lectins

Abstract

The specificity of severald-galactose-binding lectins including Agaricus bisporus (mushroom),Arachis hypogaea (peanut),Bauhinia purpurea andVicia graminea has been examined by inhibition of hemagglutination using a series of synthetic oligopeptides representing the N-terminal end of glycophorin A from N and M individuals, all carrying one or several disaccharide chains,d-Galβ1–3-d-GalNAcα-(T-hapten).

Peanut lectin was inhibited by T-hapten-carrying glycopeptides, but the presence of a cluster of disaccharide chains had no effect on the lectin specificity. On the contrary, bothAgaricus bisporus andBauhinia purpurea lectins exhibited an enhanced reactivity with polyglycosylated peptides suggesting that their combining site might include two proximal galactose residues.

All synthetic glycopeptides inhibitingVicia graminea lectin carry a cluster of T-disaccharide chains and the leucine residue at the N-terminal end, and the presence of a Glu residue at position 5 slightly increased the lectin activity. It is concluded that the binding ofVicia graminea is dependent upon a specific spatial conformation including a cluster of T-hapten chains in close vicinity of a hydrophobic surface represented by an appropriate N-terminal amino acid residue.