Production of #alpha#-galactosyl epitopes via combined use of two recombinant whole cells harboring UDP-galactose 4-epimerase and #alpha#-1, 3-galactosyltransferase

摘要

#alpha#-Galactosyl epitopes (or #alpha#-Gal, oligosaccharides with a terminal Gal#alpha#1, 3Gal sequence) are a chass of biologically important oligosaccharides in great demand in bulk quantities for basic and clinical studies on preventing hyperacute rejection in pig-to-primate organ xenotransplantaion. A truncated bovine #alpha#-1, 3-galactosyltransferase, the key enzyme responsible for the biosynthesis of the terminal structure of #alpha#-Gal, was cloned and overexpressed previously. The acceptor specificity was further studied in the present paper, and lactose and galactose derivatives were found to be good acceptors. To develop a more proficient reaction process, we report herein an example of an efficient enzymatic synthesis of #alpha#-Gal oligosaccharides catalyzed by the combination of two recombinant Escherichia coli whole cells harboring the genes of a UDP-galactose 4-epimerase and the #alpha#-1, 3-galactosyltransferase, respectively. Using lactosyl azide (LacN-3) as the acceptor for the glycosyltransferase, the combined use of the two recombinant cells efficiently produced #alpha#-Gal epitope Gal#alpha#-Gal epitope Gal#alpha#1, 3LacN-3 in 60-68% yield.