This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of Purines and Pyrimidines, Subject name: Biochemistry
Glycine is useful in all of the following except - 
Select and explain. 
A. Purine synthesis, B. Creatine synthesis, C. Spermine synthesis, D. Heme synthesis
C: Spermine synthesis
Answer: C: Spermine synthesis 
Explanation: Ans. is 'c' i.e., Spermine synthesis Glycineo Glycine is a nonessential amino acid which is synthesized from serine. Glycine is metabolized by following three pathways -It can be converted to serine, a reaction that require tetrahydrofolate {derivative of folic acidQ) and pyridoxal phosphateQ as coenzyme. Further serine is metabolized by serine dehydratase into pyruvate and NH4+.The major pathway of glycine degradation is oxidative cleavage into CO and NH4' by glycine cleavage complex of liver. H4 folate is required which is converted to N5, N10- methylene H4 folate. Thus folic acid is required forglycine metabolismQ.Glycine may be oxidatively deaminated by glycine oxidase to glyoxylic acid.o Glycine is necessary for the formation of following products:- HemeQ, purine ringQ, bile acids conjugation (formation of glycocholic acidQ, and glyco-chenodeoxycholic acid), creatineQ, glutathioneQ, glucose (by gluconeogenesis).