Glycosyl-transferase catalyzed assemblage of sialyl-Lewis(x)-saccharopeptides

A series of glycohexopyranuronic acids are coupled to glucosamines to give 'disaccharides' which have the natural N-acetyl group of the glcNAc-moiety replaced by various sugar acids (-->saccharopeptides). These saccharopeptides are surprisingly good substrates for beta(1-4)galactosyl-transferase, alpha(2-3)sialyl-transferase, and fucosyl-transferase VI. The enzymes transfer successively galactose, sialic acid, and fucose from the corresponding donors onto these acceptor substrates--despite the far reaching alterations--regio- and stereospecifically in the expected manner to yield a new class of compounds, the sialyl-Lewis(x)-saccharopeptides.