Sambucus nigra lectin (SNA) is isolated from living tissue of elderberry bark after fetuin affinity chromatography. In fact, the bark of this tree is a rich source of an NeuAc(a2 6)Gal/GalNac specific agglutinin (called S. nigra agglutinin I or SNAI) and a Gal/GalNAc-binding lectin (called S. nigra agglutinin II or SNAII). SNA-I agglutinates animal and
human erythrocytes with a slight preference for type A over type B and type O erythrocytes. (1). The lectin, originally described as lactose specific, binds preferentially to sialic acid α-2,6 Gal (found in N-glycans) or sialic acid α-2,6 GalNAc (found in O-glycans) whereas sialic acid α-2,3 Gal oligosaccharides are poor inhibitors (2). The purified SNAI is a tetramer of 140 kDa composed of two different subunits and behaves sequence similarity as a type-2 ribose inactivating proteins, but differs by its specificity and unusual molecular structure (3, 4). SNA-I is widely used for the isolation and fractionation of sialylated oligosaccharides and glycoconjugates and as reagent for the studies of soluble or cellular biomarkers.