Glycosyltransferase catalyzed assemblage of sialyl-Lewisa-saccharopeptides

A series of methyl hexopyranosiduronic acids are coupled to type I disaccharide amines to give ‘trisaccharides’ which have the natural N-acetyl group of the type I disaccharides replaced by uronic acids (→ saccharopeptides). These saccharopeptides are surprisingly good substrates for α-2,3-sialyltransferase and fucosyltransferase III. The enzymes transfer N-acetylneuraminic acid and fucose, respectively, onto these acceptor substrates, despite the far reaching alterations, regio- and stereospecifically in the expected manner to yield sialyl-Lewisa-saccharopeptides.