Glycine

Not to be confused with Glycerin.

Glycine[1]
Skeletal formula of neutral glycine
Skeletal formula of zwitterionic glycine
Ball-and-stick model of the gas-phase structure
Ball-and-stick model of the zwitterionic solid-state structure
Space-filling model of the gas-phase structure
Space-filling model of the zwitterionic solid-state structure
Names
IUPAC name
Glycine
Systematic IUPAC name
Aminoacetic acid[2]
Other names
  • 2-Aminoethanoic acid
  • Glycocol
  • Glycic acid
  • Dicarbamic acid
Identifiers
CAS Number
3D model (JSmol)
Abbreviations Gly, G
ChEBI
ChEMBL
ChemSpider
DrugBank
ECHA InfoCard 100.000.248
EC Number
  • 200-272-2
  • 227-841-8
E number E640 (flavour enhancer)
KEGG
PubChem CID
UNII
InChI
  • InChI=1S/C2H5NH2/c3-1-2(4)5/h1,3H2,(H,4,5) Y
    Key: DHMQDGOQFOQNFH-UHFFFAOYSA-N Y
  • InChI=1S/C2H5NO2/c3-1-2(4)5/h1,3H2,(H,4,5)
    Key: DHMQDGOQFOQNFH-UHFFFAOYAW
SMILES
  • C(C(=O)O)N
  • Zwitterion: C(C(=O)[O-])[NH3+]
  • C(C(=O)O)N.Cl
Properties
Chemical formula
 C2H5NO2
Molar mass 75.067 g·mol−1
Appearance White solid
Density 1.1607 g/cm3[3]
Melting point 233 °C (451 °F; 506 K) (decomposition)
Solubility in water
 249.9 g/L (25 °C)[4]
Solubility soluble in pyridine
sparingly soluble in ethanol
insoluble in ether
Acidity (pKa) 2.34 (carboxyl), 9.6 (amino)[5]
Magnetic susceptibility (χ)
 −40.3·10−6 cm3/mol
Pharmacology
B05CX03 (WHO)
Hazards
Lethal dose or concentration (LD, LC):
2600 mg/kg (mouse, oral)
Supplementary data page
Glycine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y verify (what is YN ?)
Infobox references

Glycine (symbol Gly or G;[6] /ˈɡlaɪsiːn/ ⓘ[7]) is an organic compound with the formula C2H5NO2, and is the simplest stable amino acid, distinguished by having a single hydrogen atom as its side chain. As one of the 20 proteinogenic amino acids, glycine is a fundamental building block of proteins in all life and is encoded by all codons starting with GG (GGU, GGC, GGA, and GGG).[8][9] Because of its minimal side chain, it is the only common amino acid that is not chiral, meaning it is superimposable on its mirror image.[10][11]

In the body, glycine plays several crucial roles. Its small and flexible structure is vital for the formation of certain protein structures, most notably in collagen, where glycine makes up about 35% of the amino acid content and enables the tight coiling of the collagen triple helix.[8][12] Glycine disrupts the formation of alpha-helices in secondary protein structure, in favor instead of random coils.[13] Beyond its structural role, glycine functions as an inhibitory neurotransmitter in the central nervous system,[14] particularly in the spinal cord and brainstem, where it helps regulate motor and sensory signals. Disruption of glycine signaling can lead to severe neurological disorders and motor dysfunction;[15] for example, the tetanus toxin causes spastic paralysis by blocking glycine release.[16] It also serves as a key precursor for the synthesis of other important biomolecules, including the porphyrins that form heme in blood and the purines used to build DNA and RNA.[8]

Glycine is a white, sweet-tasting crystalline solid, leading to its name from Greek word glykys (Greek: γλυκύς) or "sweet".[17][7] While the body can synthesize it, it is also obtained from the diet and produced industrially by chemical synthesis for use as a food additive, a nutritional supplement, and an intermediate in the manufacture of products such as the herbicide glyphosate.[18] In aqueous solutions, glycine exists predominantly as a zwitterion (H3N+CH2COO-), a polar molecule with both a positive and negative charge, making it highly soluble in water.[19] It can also fit into hydrophobic environment due to its minimal side chain.[20]

  1. ^ The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals (11th ed.). Merck. 1989. ISBN 091191028X., 4386
  2. ^ "Glycine". PubChem.
  3. ^ Handbook of Chemistry and Physics, CRC Press, 59th ed., 1978.
  4. ^ "Solubilities and densities". Prowl.rockefeller.edu. Archived from the original on September 12, 2017. Retrieved November 13, 2013.
  5. ^ Dawson, R.M.C., et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
  6. ^ "Nomenclature and Symbolism for Amino Acids and Peptides". IUPAC-IUB Joint Commission on Biochemical Nomenclature. 1983. Archived from the original on October 9, 2008. Retrieved March 5, 2018.
  7. ^ a b "Glycine | Definition of glycine in English by Oxford Dictionaries". Archived from the original on January 29, 2018.
  8. ^ a b c Berg JM, Tymoczko JL, Gatto GJ Jr, Stryer L (2015). Biochemistry (8th ed.). New York: W. H. Freeman and Company. p. 35. ISBN 978-1-4641-2610-9.
  9. ^ Pawlak K, Błażej P, Mackiewicz D, Mackiewicz P (January 2023). "The Influence of the Selection at the Amino Acid Level on Synonymous Codon Usage from the Viewpoint of Alternative Genetic Codes". International Journal of Molecular Sciences. 24 (2): 1185. doi:10.3390/ijms24021185. PMC 9866869. PMID 36674703.
  10. ^ Matsumoto A, Ozaki H, Tsuchiya S, Asahi T, Lahav M, Kawasaki T, et al. (April 2019). "Achiral amino acid glycine acts as an origin of homochirality in asymmetric autocatalysis". Organic & Biomolecular Chemistry. 17 (17): 4200–4203. doi:10.1039/C9OB00345B. PMID 30932119.
  11. ^ IUPAC, ed. (2014). "achiral". Compendium of Chemical Terminology (2nd ed.). International Union of Pure and Applied Chemistry. doi:10.1351/goldbook.A00292.
  12. ^ Nelson DL, Cox MM (2021). Lehninger Principles of Biochemistry (8th ed.). New York: W.H. Freeman. p. 129. ISBN 978-1-319-22800-2.
  13. ^ Pace CN, Scholtz JM (1998). "A helix propensity scale based on experimental studies of peptides and proteins". Biophysical Journal. 75 (1): 422–427. Bibcode:1998BpJ....75..422N. doi:10.1016/S0006-3495(98)77529-0. PMC 1299714. PMID 9649402.
  14. ^ Zafra F, Aragón C, Giménez C (June 1997). "Molecular biology of glycinergic neurotransmission". Molecular Neurobiology. 14 (3): 117–142. doi:10.1007/BF02740653. PMID 9294860.
  15. ^ Atchison W (2018). "Toxicology of the Neuromuscular Junction". Comprehensive Toxicology. pp. 259–282. doi:10.1016/B978-0-12-801238-3.99198-0. ISBN 978-0-08-100601-6.
  16. ^ Purves D, Augustine GJ, Fitzpatrick D, Hall WC, LaMantia AS, White LE, eds. (2018). Neuroscience (6th ed.). Sunderland, Massachusetts: Sinauer Associates. pp. 132–133. ISBN 978-1-60535-380-7.
  17. ^ Kihara H, Yamamoto Y, Sato T, Yamazaki Y, Sakakibara S, Yamaguchi S, et al. (2004). "Amino Acids". Kirk-Othmer Encyclopedia of Chemical Technology. John Wiley & Sons. doi:10.1002/0471238961.0113091411090801.a01.pub2 (inactive July 8, 2025).{{cite encyclopedia}}: CS1 maint: DOI inactive as of July 2025 (link)
  18. ^ Drauz K, Gröger H, Han O (2000). "Amino Acids". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_057. ISBN 3-527-30673-0.
  19. ^ Haynes WM, ed. (2017). CRC Handbook of Chemistry and Physics (97th ed.). Boca Raton: CRC Press. p. 5-92. ISBN 978-1-4987-5429-3.
  20. ^ Alves A, Bassot A, Bulteau AL, Pirola L, Morio B (June 2019). "Glycine Metabolism and Its Alterations in Obesity and Metabolic Diseases". Nutrients. 11 (6): 1356. doi:10.3390/nu11061356. PMC 6627940. PMID 31208147.
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