The biosynthesis of glycine begins with 3-phospho-D-glycerate being metabolize into 3-phosphohydroxypyruvate through a 3-phosphoglycerate dehydrogenase. The resulting compound 3-phosphohydroxypyruvate is transaminated into 3-phospho-L-serine through a phosphoserine transaminase. This is followed by 3-phospho-L-serine being dephosphorylated through a phosphoserine phosphatase resulting in the release of a phosphate and Serine which can then be used to synthesize glycine through a serine hydroxymethyltransferase. Serine can also be incorporated into the mitochondrion and then serine can then be used to synthesize glycine through a mitochondrial serine hydroxymethyltransferase. Glycine is then used to synthesize formic acid by first being metabolized into 5,10 methylene THF, which is transformed into a 5,10 methenyltetrahydrofolate , followed by an N10 formyl tetrahydrofolate and lastly formic acid, all through a mitochondrial C1-tetrahydrofolate synthase. Glycine can also be synthesized from threonine through a threonine aldolase resulting in the release of acetaldehyde and glycine. Glycine can also be synthesized from glyoxylate interacting with alanine through a glyoxylate aminotransferase resulting in the release of glycine and pyruvic acid.

Glycine Metabolism References