Chemical synthesis and kinetic characterization of UDP-2-deoxy- d-lyxo-hexose(“UDP-2-deoxy- d-galactose”), a donor-substrate for β-(1 → 4)- d-galactosyltransferase

Abstract

Bovine β-(1 → 4)-galactosyltransferase (GalT) transfers galactose from UDP-galactose to β- d-Glc pNAc-terminating oligosaccharides to produce N-acetyllactosamine sequences. We report here the chemical synthesis, structural characterization and enzymatic evaluation of the very labile UDP-2-deoxy- d- lyxo-hexose (“UDP-2-deoxy-galactose,” 2 as an alternate donor for GalT. Donor 2 had kinetic parameters, including a K m value of 51 μM, almost identical to those for the natural substrate UDP-galactose when β- d-Glc pNAc-O(CH 2) 8COOMe was used as the acceptor. The product of the enzymatic transfer was isolated and confirmed to have the expected 2′-deoxy- N-acetyllactosamine sequence.