Glycosylation with transferases

High selectivity and substrate specificity of glycosyl transferases make them valuable catalysts for special linkages in polymer-supported synthesis. There is, however, still a rather limited set of enzymes available to date, and the need to synthesize a variety of natural and non-natural oligosaccharides prevails. Particularly with regard to combinatorial approaches, chemical solid-phase oligosaccharide synthesis promises to meet the demands most effectively. 

A hexaglycine spacer was attached to the solid support to give a substitution of 0.2 mmol g of dry silica and the excess amino groups were then capped using acetic anhydride. In the next step a selectively cleavable, a-chymotrypsin sensitive, phenylalanine ester (2) was implemented for the release of the products from the solid support under mild conditions. Subsequently it was transformed to (3) followed by reactions with glycosyl transferases to yield (4). Finally, the desired glycopeptide was cleaved from the solid support in high yield by treatment of (4) with a-chymotrypsin (Scheme 10.1). 

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