Solid-Phase Enzymatic Synthesis of a Lewis a Trisaccharide Using an Acceptor Reversibly Bound to Sepharose

The disaccharide 2-aminoethyl O-β-D-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-β-D-glucopyranoside was reacted with thiobutyrolactone to give a disaccharide with a thiol group on the aglycone. This disaccharide was reacted with activated Thiopropyl Sepharose, which gave a disaccharide bound to Sepharose via a disulphide bond. Enzymatic fucosylation, using GDP-fucose and partially purified human milk fucosyltransferase, gave a trisaccharide in good yield, which was cleaved from Sepharose by treatment with mercaptoethanol or dithiothreitol.