UDPglucose

UDP-glucose, or uridine diphosphate glucose, is a nucleotide sugar that serves as an activated donor of glucose in a broad range of biosynthetic reactions. It consists of glucose linked to uridine diphosphate by a high-energy pyrophosphate bridge, enabling it to transfer glucose to various acceptors such as oligosaccharides, polysaccharides, and glycoproteins.

Biosynthesis and interconversion are central to its role. UDP-glucose is synthesized from glucose-1-phosphate and UTP by the enzyme UDP-glucose pyrophosphorylase, producing UDP-glucose and pyrophosphate, with pyrophosphate rapidly hydrolyzed to drive the reaction forward. The molecule can be interconverted with UDP-galactose by UDP-glucose 4-epimerase, and it can be oxidized to UDP-glucuronate by UDP-glucose dehydrogenase, a step needed for the production of certain glycosaminoglycans and related polysaccharides.

Functions and roles are diverse. UDP-glucose provides glucose residues for the synthesis of glycans and glycoconjugates, including glycogen formation in animals and the production of cell wall polysaccharides in plants. It also serves as a substrate for the biosynthesis of complex polysaccharides in bacteria, such as those required for lipopolysaccharides and capsule formation. In many organisms, a network of glycosyltransferases uses UDP-glucose to install glucose units onto growing carbohydrate chains and to generate diversity in glycan structures.

Clinical and biotechnological relevance arises from its central role in glycosylation pathways and polysaccharide biosynthesis, making UDP-glucose a key metabolite in cellular architecture and metabolism.