Glycine
![](/Images/godic/202501/15/Glycine-protonation-states-2D-skeletal0742.png")
![](/Images/godic/202501/15/L-amino_acid_any0742.png")
Glycine (abbreviated as Gly or G) is the smallest of the 20 amino acids commonly found in proteins, and indeed is the smallest possible (having a hydrogen substituent as its side-chain). The formula is NH2CH2COOH. Its codons are GGU, GGC, GGA, GGG of the genetic code.