Enzymatic Synthesis of Oligosaccharide Analogues: Evaluation of UDP-Gal Analogues as Donors for Three Retaining α-Galactosyltransferases

A series of deoxygenated uridine 5‘-diphosphogalactose (UDP-Gal) derivatives are evaluated as donors for three different retaining galactosyltransferases using capillary electrophoresis with laser-induced fluorescence detection. The enzymes investigated were calf thymus α(1→3) galactosyltransferase (E.C. 2.4.1.151), blood group B α(1→3) galactosyltransferase (E.C. 2.4.1.37) and Neisseria meningitidis α(1→4) galactosyltransferase. UDP-2-deoxy-Gal and UDP-6-deoxy-Gal were found to be active as donors for all three enzymes. Preparative syntheses utilizing these UDP-Gal derivatives were performed on mg scales, affording deoxygenated trisaccharide analogues in 5−100% yields.