Convenient enzymatic synthesis of a p-nitrophenyl oligosaccharide series of sialyl N-acetyllactosamine, sialyl Lex and relevant compounds

From the β-d-Gal-(1→4)-β-d-GlcNAc-OC6H4NO2-p (1) prepared by the transglycosylation of β-galactosidase from Bacillus circulans, α-d-Neu5Ac-(2→3)-β-d-Gal-(1→4)-β-d-GlcNAc-OC6H4NO2-p (9) and α-d-Neu5Ac-(2→6)-β-d-Gal-(1→4)-β-d-GlcNAc-OC6H4NO2-p (10) were effectively synthesized with an equimolar ratio of CMP-Neu5Ac by recombinant rat α-(2→3)-N-sialyltransferase and rat liver α-(2→6)-N-sialyltransferase, respectively. The former enzyme also transferred effectively the Neu5Ac residue from CMP-Neu5Ac to the location of OH-3 in the non-reducing terminal of β-d-Gal-(1→4)-β-d-Gal-OC6H4NO2-p or β-d-Gal-(1→4)-β-d-Gal-(1→4)-β-d-GlcNAc-OC6H4NO2-p, while the latter enzyme did not. In the case of equimolar ratio of GDP-Fuc/acceptor, 1 and 9 were further fucosylated quantitatively to form β-d-Gal-(1→4)-β-d-(α-l-Fuc-(1→3)-)-GlcNAc-OC6H4NO2-p (14) and α-d-Neu5Ac-(2→3)-β-d-Gal-(1→4)-β-d-(α-l-Fuc-(1→3)-)-GlcNAc-OC6H4NO2-p (13) by recombinant human α-(1→3)-fucosyltransferase VII, respectively.