Regiospecific glycosidase-assisted synthesis of lacto-N-biose I (Gal beta 1-3GlcNAc) and 3 '-sialyl-lacto-N-biose I (NeuAc alpha 2-3Gal beta 1-3GlcNAc)

The all-transglycolytic synthesis of lacto-N-biose I (Gal beta 1-3GlcNAc) a nd 3'-sialyl-lacto-N-biose I (NeuAc alpha 2-3Gal beta 1-3GlcNAc) was perfor med. The disaccharide lacto-N-biose I was obtained by use of p-nitrophenyl beta-D-galactopyranoside as the donor, 2-acetamido-2-deoxy-D-glucopyranose as the acceptor and Xanthomonas manihotis beta-D-galactosidase as the catal yst. The reaction was shown to be regiospecific, with a high molar yield (a bout 55%) with respect to the donor. Lacto-N-biose I obtained by this metho d was used as the acceptor for a subsequent enzymatic reaction catalyzed by Trypanosoma cruzi trans-sialidase in which 2'-(4-methylumbellyferyl)-alpha -D-N-acetylneuraminic was used as the donor of the N-acetylneuraminil moiet y. The reaction generated the product, 3'-sialyl-lacto-N-biose I, regiospec ifically and with a molar yield of about 35%.