All of the following amino acids are one-carbon donors, EXCEPT: (A) Glycine, (B) Serine, (C) Histidine, (D) Threonine
Answer is D. Sources of one-carbon groups: Serine to glycine (Serine hydroxymethyl transferase reaction) is the primary contributor for methylene THFA. Glycine cleavage system produces methylene groups is the glycine cleavage system Histidine contributes to N5-formimino THFA through FIGLU Tryptophan donates formyl-THFA Choline and betaine are donors of hydroxy methyl groups