De novo purine ring synthesis draws its atoms from several precursors. Which precursor contributes both carbon 2 and carbon 8 of the finished purine ring?
- A N10-formyl tetrahydrofolate ✓
- B Glycine
- C Aspartate
- D Glutamine
Correct answer: A. N10-formyl tetrahydrofolate
Explanation
The one-carbon units carried by N10-formyl tetrahydrofolate are incorporated at C8 (early, onto glycinamide ribonucleotide) and C2 (late, onto aminoimidazole carboxamide ribonucleotide). Glycine contributes C4, C5 and N7; glutamine supplies N3 and N9; aspartate supplies N1. This folate dependence explains why antifolate drugs suppress purine synthesis.
Reference: Lippincott's Illustrated Reviews: Biochemistry, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.