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

2. 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.

3. 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

4. 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.