Biochemistry department Uronic Acid Pathway Dr. Sooad Al-Daihan Biochemistry department

Overview It is an alternative oxidative pathway for glucose that doesn’t lead to ATP generation. It includes oxidation of glucose to Glucuronic acid Ascorbic acid It occurs mainly in the liver cytoplasm.

Metabolic reactions Glucose 6-phosphate is isomerized to glucose 1-phosphate Glucose 1-phosphate reacts with uridine triphosphate (UTP) to form uridine diphosphate glucose (UDPGlc) in a reaction catalyzed by UDPGlc pyrophosphorylase UDPGlc is oxidized at carbon 6 by NAD-dependent UDPGlc dehydrogenase in a two-step reaction to yield UDP-glucuronate 1 2 3

UDP Glucuronic acid (active form) is needed in: Conjugation to less polar compounds as bilirubin, steroids and some drugs making them more water soluble (detoxicated) . Synthesis of glycosaminoglycans (mucopolysaccharide) as heparin, hyaluronic acid. In plants and some animals (not Human) glucuronic acid serves as a precursor of L-ascorbic acid. The uronic acid pathway also provides a mechanism by which dietary D-xylulose enter the central pathway.