GlcA

GlcA is short for glucuronic acid, a hexuronic sugar derived from glucose by oxidation of the C-6 hydroxymethyl group to a carboxyl group. In solution it predominantly exists as the glucuronate anion at physiological pH and, like other uronic acids, forms a six-membered ring (pyranose) with several possible anomeric configurations. Its chemical properties and oxidation state make it a key component in metabolism and polysaccharide structure.

In biology, glucuronic acid is typically encountered as UDP-glucuronic acid (UDP-GlcA), the activated donor used by UDP-glucuronosyltransferases to conjugate glucuronic acid onto a wide range of substrates. This glucuronidation pathway enhances the solubility and excretion of endogenous compounds such as bilirubin and steroid hormones, as well as numerous xenobiotics and drugs. UDP-GlcA is produced from UDP-glucose by UDP-glucose dehydrogenase and serves as a universal activated form for glucuronidation reactions.

GlcA is also a structural component of glycosaminoglycans and proteoglycans. In hyaluronic acid and many other proteoglycans, repeating disaccharide units contain glucuronic acid linked to amino sugar residues, contributing to the hydration, viscoelasticity, and integrity of extracellular matrices in connective tissues.

Beyond its role in macromolecules, glucuronic acid participates in carbohydrate metabolism and serves as a precursor for derivatives involved in detoxification and clearance processes across organisms.