Comparative analysis by frontal affinity chromatography of oligosaccharide specificity of GlcNAc-binding lectins, Griffonia simplicifolia lectin-II (GSL-II) and Boletopsis leucomelas lectin (BLL).

Lectin-based structural glycomics requires a search for useful lectins and their biochemical characterization to profile complex features of glycans. In this paper, two GlcNAc-binding lectins are reported with their detailed oligosaccharide specificity. One is a classic plant lectin, Griffonia simplicifolia lectin-II (GSL-II), and the other is a novel fungal lectin, Boletopsis leucomelas lectin (BLL). Their sugar-binding specificity was analyzed by frontal affinity chromatography using 146 glycans (125 pyridylaminated and 21 p-nitrophenyl saccharides). As a result, it was found that both GSL-II and BLL showed significant affinity toward complex-type N-glycans, which are either partially or completely agalactosylated. However, their branch-specific features differed significantly: GSL-II strongly bound to agalacto-type, tri- or tetra-antennary N-glycans with its primary recognition of a GlcNAc residue transferred by GlcNAc-transferase IV, while BLL preferred N-glycans with fewer branches. In fact, the presence of a GlcNAc residue transferred by GlcNAc-transferase V abolishes the binding of BLL. Thus, GSL-II and BLL forms a pair of complementally probes to profile a series of agalacto-type N-glycans.