Combined chemical-enzymic synthesis of deoxygenated oligosaccharide analogs: transfer of deoxygenated D-GlcpNAc residues from their UDP-GlcpNAc derivatives using N-acetylglucosaminyltransferase I

Article abstract of DOI:10.1016/0008-6215(90)84053-W

The 3"-,4"-, and 6"-deoxy analogs of UDP-GlcpNAc have been synthesized chemically and found to act as donor-substrates for N-acetylglucosaminyltransferase-I (GnT-I) from human milk.Incubation of UDP-GlcpNAc and these deoxy analogs with GnT-I in the presence of α-D-Manp-(1->3)-<α-D-Manp-(1->6)>-β-D-Manp-O(CH2)8COOMe gave β-D-GlcpNAc-(1->2)-α-D-Manp-(1->3)-<α-D-Manp-(1->6)>-β-D-Manp-O(CH2)8COOMe(6), and the deoxy analogs 12-14 where HO-3, HO-4, and HO-6, respectively, of the β-D-GlcNAc residue were replaced by hydrogen.The tetrasaccharide glycosides 6 and 12-14 were characterized by 1H-n.m.r. spectroscopy and evaluated as acceptors for GnT-II, the next enzyme in the pathway of biosynthesis of Asn-linked oligosaccharides.Deoxygenation of the 3-position of the β-D-GlcNAc residue of 6 completely abolished its acceptor activity, whereas removal of HO-4 or HO-6 caused only modest decreases in activity.