Synthesis and binding analysis of unique AG2 pentasaccharide to human Siglec-2 using NMR techniques

Siglec-2 is a mammalian sialic acid binding protein expressed on B-cell surfaces and is involved in the modulation of B-cell mediated immune response. We synthesized a unique starfish ganglioside, AG2 pentasaccharide Galf beta(1-3)Galp alpha(1-4)Neu5Ac alpha(2-3)Galp beta(1-4)Glcp, and found that the synthetic pentasaccharide binds to human Siglec-2 by performing (1)H NMR experiments. Saturation transfer difference NMR experiments indicated that the C7-C9 side-chain and the acetamide moiety of the central sialic acid residue were located in the binding face of human Siglec-2. We determined the binding epitope of AG2 pentasaccharide to human Siglec-2, as the Galp alpha(1-4)Neu5Ac alpha(2-3)Galp unit. (C) 2010 Elsevier Ltd. All rights reserved.