Nucleotide Sugar Regeneration
Enzyme modules for in situ regeneration of nucleotide sugars have been developed in our group for the following nucleotide sugars: UDP-D-Glc/UDP-D-Gal, dTDP-L-Rha, UDP-GlcA. These enzyme modules are flexible for the combination with appropriate glycosyltransferases (GT-modules) to gain economic synthesis of glycoconjugates. The synthesis of glycoconjugates was realized with in situ regeneration of nucleotide sugars employing sucrose synthase [18, 20, 49, 84 ]. Regeneration of UDP-Gal in combination with β4GalT-1 was established leading to the 0.5 g scale synthesis of N-Acetyllactosamine (LacNAc), an important building block in sugar-epitopes. The combination of β4Gal-T1 with α3Gal-T yielded the Galili-epitope, Gal(α1-3)Gal(β1-4)GlcNAc(β1-R), the xenotransplantation-antigen, starting from the monosaccharide GlcNAc(β1-R) [ 20, 38 ]. The regeneration of dTDP-deoxysugars such as dTDP-L-Rha was realized on the basis of sucrose . Also, the regeneration of UDP-GlcA was accomplished for the synthesis of glucuronides, e.g. the non-sulfated HNK-1 epitope .