A biochemistry student is comparing the two branches that convert IMP into the adenylic and guanylic nucleotides. Which pairing of amino acid donor and required nucleoside triphosphate is correct for the conversion of IMP to GMP?

• A Aspartate as amino donor, GTP as energy source
• B Glutamine as amino donor, ATP as energy source ✓
• C Glutamine as amino donor, GTP as energy source
• D Aspartate as amino donor, ATP as energy source

Explanation

IMP to GMP proceeds through xanthylate, using the amide nitrogen of glutamine and ATP as the energy source. The reciprocal branch, IMP to AMP, uses aspartate as the amino donor and GTP as the energy source. This cross-regulation ensures balanced production: falling GTP slows AMP synthesis and falling ATP slows GMP synthesis.

Reference: Lehninger Principles of Biochemistry, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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