N-Acetylhexosamine triad in one molecule: Chemoenzymatic introduction of 2-acetamido-2-deoxy-β-d-galactopyranosyluronic acid residue into a complex oligosaccharide |
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| Authors: | Pavla Bojarov Karel K&#x;enek Marek Kuzma Lucie Petrskov Karel Bezou&#x;ka Darius-Jean Namdjou Lothar Elling Vladimír K&#x;en |
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| Institution: | aInstitute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ 142 20 Prague 4, Czech Republic;bLaboratory for Biomaterials, Department of Biotechnology and Helmholtz-Institut for Biomedical Engineering, Aachen University, D 52074 Aachen, Germany;cDepartment of Biochemistry, Faculty of Sciences, Charles University Prague, Hlavova 8, CZ 128 40 Prague 2, Czech Republic |
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| Abstract: | A complex trisaccharide β-d-GalpNAcA-(1 → 4)-β-d-GlcpNAc-(1 → 4)-d-ManpNAc (3) was prepared in a good yield (35%) in a transglycosylation reaction catalyzed by β-N-acetylhexosaminidase from Talaromyces flavus using p-nitrophenyl 2-acetamido-2-deoxy-β-d-galacto-hexodialdo-1,5-pyranoside (1) as a donor followed by the in situ oxidation of the aldehyde functionality by NaClO2. The disaccharide β-d-GlcpNAc-(1 → 4)-d-ManpNAc (2) was used as galactosyl acceptor. A disaccharide β-d-GalpNAcA-(1 → 4)-d-GlcpNAc (4; 39%) originated as a by-product in the reaction. Oligosaccharides comprising a carboxy moiety at C-6 are shown to be very efficient ligands to natural killer cell activation receptors, particularly to human receptor CD69. Thus, oxidized trisaccharide 3 is the best-known oligosaccharidic ligand to this receptor, with IC50 = 2.5 × 10−9 M. The presented method of introducing a β-d-GalpNAcA moiety into carbohydrate structures is versatile and can be applied in the synthesis of other complex oligosaccharides. |
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| Keywords: | β -N-acetylhexosaminidase Talaromyces flavus Galactopyranosiduronic acid Modified substrate Natural killer cell Transglycosylation |
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