Expression of a Recombinant Human Glycosyltransferase from a Synthetic Gene and its Utilization for Synthesis of the Human Blood Group B Trisaccharide

A 1034‐bp synthetic gene encoding the human blood group B glycosyltransferase, which catalyzes the transfer of galactose from UDP‐Gal to Fucα(l‐2)Galβ‐OR to give the blood group B determinant Galα(l‐3)[Fucα(1‐2)]Gal β‐OR (where R is a glycoprotein or glycolipid), has been expressed in Escherichia coli by replacing its membrane‐anchoring domain with an omp A bacterial secretory signal. The active enzyme was purified from the periplasm using UDP‐hexanolamine affinity chromatography and used in the synthesis of preparative amounts of the human blood group B trisaccharide antigen. The substrate specificity and kinetics of the recombinant enzyme were comparable to the enzyme from human sera. Thus we have achieved the construction of a completely synthetic glycosyltransferase gene and its successful expression.