In the Phase II detoxification reactions, glucuronidation is the MOST quantitatively important conjugation reaction. The activated donor molecule for glucuronidation is:
- A UDP-galactose
- B S-adenosylmethionine (SAM)
- C UDP-glucuronic acid (UDPGA) ✓
- D 3'-phosphoadenosine-5'-phosphosulfate (PAPS)
Correct answer: C. UDP-glucuronic acid (UDPGA)
Explanation
UDP-glucuronosyltransferases (UGTs) transfer glucuronic acid from UDP-glucuronic acid (UDPGA) to a nucleophilic substrate (-OH, -COOH, -NH2, -SH). UDPGA is formed from UDP-glucose by UDP-glucose dehydrogenase. SAM is the methyl donor for methylation reactions; PAPS is the activated sulfate donor for sulfation. Glucuronidation increases water solubility and facilitates biliary or renal excretion of drugs, bilirubin, and steroid hormones.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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