CHEMICAL SYNTHESIS AND KINETIC CHARACTERIZATION OF DP-2-DEOXY-D-LYXO-HEXOSE(UDP-2-DEOXY-D-GALACTOSE), A DONOR-SUBSTRATE FOR BETA-(1-]4)-D-GALACTOSYLTRANSFERASE

Bovine beta-(1 --> 4)-galactosyltransferase (GalT) transfers galactose from UDP-galactose to beta-D-Glc p NAc-terminating oligosaccharides t o produce N-acetyllactosamine sequences. We report here the chemical s ynthesis, structural characterization and enzymatic evaluation of the very labile UDP-2-deoxy-D-lyxo-hexose (''UDP-2-deoxy-galactose,'' 2) a s an alternate donor for GalT. Donor 2 had kinetic parameters, includi ng a K(m), value of 51 muM, almost identical to those for the natural substrate UDP-galactose when beta-D-Glc p NAc-O(CH2)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.