Enzymatic synthesis of UDP-galactose on a gram scale

Uridine 5′-diphospho-α-d-galactose (UDP-Gal) was synthesized on a gram scale from uridine 5′-diphospho-α-d-glucose and α-d-galactose 1-phosphate using the enzymes galactose-1-phosphate uridyltransferase (EC 2.7.7.12), phosphoglucomutase (EC 2.7.5.1) and glucose-6-phosphate dehydrogenase (EC 1.1.1.27). The synthesis was performed in a repetitive batch mode in which the enzymes, some of which are expensive, were used in 16 subsequent batches without any loss of enzyme activity. The space time yield of the synthesis was 7.1 g/l d. The overall yield of the synthesis amounted to 40% and 1.1 gram of pure UDP-Gal was obtained.