Synthesis of the carbocyclic analog of uridine 5′-(α-D-galactopyranosyl diphosphate) (UDP-Gal) as an inhibitor of β(1 → 4)-galactosyltransferase

Uridine 5′-(5a-carba-α-D-galactopyranosyl diphosphate), the carbocyclic analog of UDP-galactose where the ring oxygen of the galactose residue is replaced by a methylene group, was chemically synthesized as a potential inhibitor of galactosyltransferases. It was found to be a competitive inhibitor of UDP-galactose: N-acetylglucosamine β(1 → 4)-galactosyltransferase from bovine milk (EC 2.4.1.22) with a K i value of 58 µM, similar to the K m value for UDP-galactose (25 µM).