This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of protein and amino acid, Subject name: Biochemistry
All of the following degradation product of Glycine except 
Select and explain. 
A. Serine, B. Oxalates, C. Pyruvates, D. Ornithine
D: Ornithine
Answer: D: Ornithine 
Explanation: Glycine undergoes oxidative deamination by glycine synthase to librate NH4+, COm and one carbon fragment as N5, N10- methylene THF. This provides a major route of glycine break down.Glycine is reversibly conveed to Serin by THF dependent serine hydroxymethyltransferase. Pyruvate produced from serine by serine dehydratase. Serine is degraded to glyoxylate. Glycine is also conveed to oxalate, an excretory product.Ref: Biochemistry, U. Satyanarayana, Fouh edition, page no: 342