Enzymatic-Synthesis of the α3-Galactosyl-Le X Tetrasaccharide: A Potential Ligand for Selectin-Type Adhesion Molecules

Abstract

Using recombinant UDP-Gal:Galβ1→4GlcNAc α1,3-galactosyltransferase and human milk α1,3-fucosyltransferase the disaccharide Galβ1→4GlcNAc has been converted in vitro into a tetrasaccharide product. The product has been characterized by gel filtration chromatography and HPLC and was analyzed using 1H-NMR. Based on NMR spectral data along with the known linkage specificity of the α1,3-galactosyltransferase and the α1,3-fucosyltransferase used, the chromatographic behaviour of the product, and the 1:1 molar ratios of the galactose and fucose residues calculated from incorporated radioactivity, it is concluded that the structure of the tetrasaccharide product is Galα1→3Galβ1→4[Fucα1→3]-GlcNAc. The tetrasaccharide is a non-charged analogue of the sialyl-Le X determinant that potentially may act as a ligand structure in selectin-mediated cell-cell adhesion.