Synthesis of α-Gal epitope derivatives with a galactosyltransferase–epimerase fusion enzyme

α-Gal epitopes are carbohydrate structures bearing an α-d-Galp-(1→3)-β-d-Galp terminus and are the main cause of antibody-mediated hyperacute rejection in xenotransplantation. Nine monosaccharides and ten disaccharides were evaluated as substrates for a fusion protein, which contains both α-(1→3)-galactosyltransferase and uridine-5′-diphosphogalactose 4-epimerase. Four disaccharide and six trisaccharide α-Gal epitope derivatives were synthesized utilizing this novel fusion enzyme.