Glycine is useful in all of the following synthetic processes, EXCEPT:
Purine synthesis
Creatine synthesis
Heme synthesis
Synthesis of spermine
Glycine is incorporated into creatine, and the nitrogen and -carbon of glycine are incorporated into the pyrrole rings and the methylene bridge carbons of heme, and the entire glycine molecule becomes atoms 4, 5, and 7 of purines. Following decarboxylation of S-adenosylmethionine by methionine decarboxylase, three carbons and the alpha-amino group of methionine contribute to the biosynthesis of the polyamines spermine and spermidine. Ref: Rodwell V.W. (2011). Chapter 30. Conversion of Amino Acids to Specialized Products. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.