Biocatalytic preparation of N-glycolylneuraminic acid, deaminoneuraminic acid (KDN) and 9-azido-9-deoxysialic acid oligosaccharides

A facile approach for preparative synthesis of sialyloligosaccharides containing N-glycolylneuraminic acid, deaminoneuraminic acid, and two 9-azido derivatives is described. Synthesis is accomplished by use of 6-carbon mannose/mannosamine precursors employing an aldolase, CMP-sialic acid synthetase, and sialyltransferase. Using a combination of five different sialyltransferases and various acceptor substrates, 16 sialosides representing sequences found in glycoproteins and glycolipids were synthesized with typical yields of 60-80%.