Editing Glycine (section)

===Biosynthesis===
Glycine is not [[Essential amino acid#Essentiality in humans|essential to the human diet]], as it is biosynthesized in the body from the amino acid [[serine]], which is in turn derived from [[3-phosphoglycerate]]. In most organisms, the enzyme [[serine hydroxymethyltransferase]] catalyses this transformation via the cofactor [[pyridoxal phosphate]]:<ref name="Lehninger" />
: serine + [[tetrahydrofolate]] → glycine + [[5,10-Methylenetetrahydrofolate|''N<sup>5</sup>'',''N<sup>10</sup>''-methylene tetrahydrofolate]] + H<sub>2</sub>O

In ''E. coli'', antibiotics that target folate depletes the supply of active tetrahydrofolates, halting glycine biosynthesis as a consequence.<ref>{{cite journal | vauthors = Kwon YK, Higgins MB, Rabinowitz JD | title = Antifolate-induced depletion of intracellular glycine and purines inhibits thymineless death in E. coli | journal = ACS Chemical Biology | volume = 5 | issue = 8 | pages = 787–795 | date = August 2010 | pmid = 20553049 | pmc = 2945287 | doi = 10.1021/cb100096f }}</ref>

In the liver of [[vertebrate]]s, glycine synthesis is catalyzed by [[glycine synthase]] (also called glycine cleavage enzyme).  This conversion is readily [[Reversible reaction|reversible]]:<ref name="Lehninger" />
: CO<sub>2</sub> + NH{{su|b=4|p=+}} + ''N<sup>5</sup>'',''N<sup>10</sup>''-methylene tetrahydrofolate + [[Nicotinamide adenine dinucleotide|NADH]] + H<sup>+</sup> ⇌ Glycine + tetrahydrofolate + [[Nicotinamide adenine dinucleotide|NAD]]<sup>+</sup>

In addition to being synthesized from serine, glycine can also be derived from [[threonine]], [[choline]] or hydroxyproline via inter-organ metabolism of the liver and kidneys.<ref>{{cite journal | vauthors = Wang W, Wu Z, Dai Z, Yang Y, Wang J, Wu G | title = Glycine metabolism in animals and humans: implications for nutrition and health | journal = Amino Acids | volume = 45 | issue = 3 | pages = 463–477 | date = September 2013 | pmid = 23615880 | doi = 10.1007/s00726-013-1493-1 | s2cid = 7577607 }}</ref>