Creatine, stored in muscle as phosphocreatine, is synthesized from which three precursors?

• A Histidine, beta-alanine, and SAM
• B Glutamate, cysteine, and glycine
• C Aspartate, citrulline, and methionine
• D Glycine, arginine, and S-adenosylmethionine ✓

Explanation

Creatine synthesis begins in kidney where glycine amidinotransferase condenses glycine and arginine to guanidinoacetate, releasing ornithine. Guanidinoacetate is then methylated by guanidinoacetate methyltransferase using S-adenosylmethionine as the methyl donor, mainly in liver. Glutamate, cysteine and glycine form glutathione, aspartate and citrulline feed the urea cycle, and histidine with beta-alanine forms carnosine, so each distractor belongs to a different biosynthetic pathway.

Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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