UDPglukosiä

UDPglukosiä, a nucleotide sugar known in English as UDP‑glucose, is the uridine diphosphate ester of glucose. Its structure consists of a uridine moiety linked via a diphosphate bridge to a D‑glucose molecule, yielding the chemical formula C11H18N5O17P3. It is a key donor of glucose units in glycoconjugate synthesis and is produced in cells by the enzyme UDP‑glucose pyrophosphorylase.

Biosynthesis of UDPglukosiä starts from glucose‑6‑phosphate. The glucose moiety undergoes isomerization to glucose‑1‑phosphate, which reacts with uridine triphosphate (UTP) to form UDPglukosiä and pyrophosphate. This reversible reaction is catalyzed by UDP‑glucose pyrophosphorylase, which is regulated by cellular energy status and the availability of substrates.

Functions of UDPglukosiä include glycogenesis, glycolipogenesis, and glycoprotein formation. In glycogen synthesis, the enzyme glycogen synthase transfers a glucose unit from UDPglukosiä to the growing glycogen chain, simultaneously releasing UDP. In the biosynthesis of glycolipids and glycoproteins, UDPglukosiä serves as a glucose donor in the activities of glycosyltransferases, enabling the attachment of glucose residues to lipids and proteins. Additionally, UDPglukosiä participates in the synthesis of nucleotide sugars for cell wall components in plants and bacterial peptidoglycan precursors.

Clinically, alterations in UDPglukosiä metabolism contribute to metabolic disorders such as glycogen storage diseases (e.g., type III) and can affect the biosynthesis of glycosylated therapeutic proteins. In biotechnology, UDPglukosiä is used as a substrate in enzymatic synthesis of glycoconjugates and as a building block in the production of bioactive carbohydrate derivatives.