Uronic Acid Pathway
Start with the big picture
The pathway begins when UDP-glucose dehydrogenase oxidizes UDP-glucose to UDP-glucuronate, using NAD⁺ and producing NADH. It operates mainly in the liver, with activity also noted in kidney and intestinal mucosa, and generates no ATP. UDP-glucuronate supplies glucuronic acid for conjugation of bilirubin, drugs, steroid hormones, and other compounds, helping increase their solubility for excretion. It also contributes to glycosaminoglycan synthesis. In species able to synthesize vitamin C, it can feed ascorbic acid production; humans lack the required L-gulonolactone oxidase. The pathway also connects to pentose phosphate metabolism through formation of D-xylulose. Its distinguishing oxidation occurs at carbon 6, unlike the HMP shunt’s oxidation at carbon 1.
What you'll learn
- Describe the conversion of UDP-glucose to UDP-glucuronate and identify the enzyme involved.
- Explain how UDP-glucuronate supports conjugation and glycosaminoglycan synthesis.
- Distinguish the pathway’s oxidation site from that of the HMP shunt.
- Relate pathway function to vitamin C synthesis across species and human limitations.
- Recognize clinical connections involving bilirubin glucuronidation and essential pentosuria.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
