Glycine

For the plant, see Glycine (plant).

Template:Chembox AbbreviationsTemplate:Chembox E numberTemplate:Chembox AppearanceTemplate:Chembox DensityTemplate:Chembox MeltingPtTemplate:Chembox SolubilityInWaterTemplate:Chembox SolubilityTemplate:Chembox pKaTemplate:Chembox SDSTemplate:Chembox Lethal amounts (set)Template:Chembox Supplement Glycine[1] Template:Chembox image sbs cell

Template:Chembox image sbs cell
Names
IUPAC name

Glycine

Other names

Aminoethanoic acid
Aminoacetic acid

Identifiers

CAS Number

* 56-40-6 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 730

ECHA InfoCard | Lua error in Module:Wikidata at line 879: attempt to index field 'wikibase' (a nil value). Lua error in Module:Wikidata at line 879: attempt to index field 'wikibase' (a nil value).

IUPHAR/BPS

* 727

PubChem CID

* 750

UNII |

* TE7660XO1C Y

InChI

* InChI=1/C2H5NO2/c3-1-2(4)5/h1,3H2,(H,4,5)

Key: DHMQDGOQFOQNFH-UHFFFAOYAW

SMILES

* C(C(=O)O)N

Properties

Chemical formula

| C2H5NO2
Molar mass | 75.07
Hazards

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 (abbreviated as Gly or G)[2] is an organic compound with the formula NH2CH2COOH. With only two hydrogen atoms as its 'side chain', glycine is the smallest of the 20 amino acids commonly found in proteins. Its codons are GGU, GGC, GGA, GGG.

Glycine is a colourless, sweet-tasting crystalline solid. It is unique among the proteinogenic amino acids in that it is not chiral. It can fit into hydrophilic or hydrophobic environments, due to its two hydrogen atom side chain.

## Contents

* 1 Production and key properties
* 2 Biosynthesis
* 3 Degradation
* 4 Physiological function
* 4.1 As a biosynthetic intermediate
* 4.2 As a neurotransmitter
* 5 Commercial uses
* 5.1 Animal and human foods
* 5.2 Cosmetics and miscellaneous applications
* 5.3 Chemical feedstock
* 6 Presence in space
* 7 See also
* 8 References
* 9 Further reading
* 10 External links

## Production and key properties

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Glycine was discovered in 1820, by Henri Braconnot who boiled gelatin with sulfuric acid.[3]

Glycine is manufactured industrially by treating chloroacetic acid with ammonia:[4]

ClCH2COOH + 2 NH3 → H2NCH2COOH + NH4Cl

About 15M kg are produced annually in this way.[5]

In the USA (by GEO Specialty Chemicals, Inc.) and in Japan (by Shoadenko), glycine is produced via the Strecker amino acid synthesis.[6]

There are two producers of glycine in the United States. Chattem Chemicals, Inc., purchased by Sun Pharmaceutical, who is an international pharmaceutical company based in Mumbai, India and GEO Specialty Chemicals, Inc., who purchased the glycine and naphthalene sulfonate production facilities of Dow/Hampshire Chemical Corp.[6][7]

Chattem's manufacturing process ("MCA" process) occurs in batches and results in a finished product with some residual chloride but no sulfate, while GEO’s manufacturing process is considered a semi-batch process and results in a finished product with some residual sulfate but no chloride.

Its pK values are 2.35 and 9.78, so above pH 9.78, most of the glycine exists as the anionic amine, H2NCH2CO2-. Below pH 2.35, its solutions contain mostly the cationic carboxylic acid H3N+CH2CO2H. Its isoelectric point (pI) is 6.06.

## Biosynthesis

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Glycine is not 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:[8]

serine + tetrahydrofolate → glycine + N5,N10-Methylene tetrahydrofolate + H2O

In the liver of vertebrates, glycine synthesis is catalyzed by glycine synthase (also called glycine cleavage enzyme). This conversion is readily reversible:[8]

CO2 \+ NH4+ \+ N5,N10-Methylene tetrahydrofolate + NADH + H+ → Glycine + tetrahydrofolate + NAD+

Glycine is coded by codons GGU, GGC, GGA and GGG. Most proteins incorporate only small quantities of glycine. A notable exception is collagen, which contains about 35% glycine.[8]

## Degradation

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Glycine is degraded via three pathways. The predominant pathway in animals involves the catalysis of glycine cleavage enzyme, the same enzyme also involved in the biosynthesis of glycine. The degradation pathway is the reverse of this synthetic pathway:[8]

Glycine + tetrahydrofolate + NAD+ → CO2 \+ NH4+ \+ N5,N10-Methylene tetrahydrofolate + NADH \+ H+

In the second pathway, glycine is degraded in two steps. The first step is the reverse of glycine biosynthesis from serine with serine hydroxymethyl transferase. Serine is then converted to pyruvate by serine dehydratase.[8]

In the third pathway of glycine degradation, glycine is converted to glyoxylate by D-amino acid oxidase. Glyoxylate is then oxidized by hepatic lactate dehydrogenase to oxalate in an NAD+-dependent reaction.[8]

## Physiological function

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The principal function of glycine is as a precursor to proteins. It is also a building block to numerous natural products.

### As a biosynthetic intermediate

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In higher eukaryotes, D-Aminolevulinic acid, the key precursor to porphyrins, is biosynthesized from glycine and succinyl-CoA. Glycine provides the central C2N subunit of all purines.[8]

### As a neurotransmitter

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Glycine is an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord, brainstem, and retina. When glycine receptors are activated, chloride enters the neuron via ionotropic receptors, causing an Inhibitory postsynaptic potential (IPSP). Strychnine is a strong antagonist at ionotropic glycine receptors, whereas bicuculline is a weak one. Glycine is a required co-agonist along with glutamate for NMDA receptors. In contrast to the inhibitory role of glycine in the spinal cord, this behaviour is facilitated at the (NMDA) glutaminergic receptors which are excitatory.[citation needed] The Template:LD50 of glycine is 7930 mg/kg in rats (oral),[9] and it usually causes death by hyperexcitability.

## Commercial uses

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In the US, glycine is typically sold in two grades: United States Pharmacopeia (“USP”), and technical grade. Most glycine is manufactured as USP grade material for diverse uses. USP grade sales account for approximately 80 to 85 percent of the U.S. market for glycine.

* Pharmaceutical grade glycine is produced for some pharmaceutical applications, such as intravenous injections, where the customer’s purity requirements often exceed the minimum required under the USP grade designation. Pharmaceutical grade glycine is often produced to proprietary specifications and is typically sold at a premium over USP grade glycine.
* Technical grade glycine, which may or may not meet USP grade standards, is sold for use in industrial applications; e.g., as an agent in metal complexing and finishing. Technical grade glycine is typically sold at a discount to USP grade glycine.[10]

### Animal and human foods

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Other markets for USP grade glycine include its use an additive in pet food and animal feed. For humans, glycine is sold as a sweetener/taste enhancer. Food supplements and protein drinks contain glycine. Certain drug formulations include glycine to improve gastric absorption of the drug.

### Cosmetics and miscellaneous applications

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Glycine serves as a buffering agent in antacids, analgesics, antiperspirants, cosmetics, and toiletries.

Many miscellaneous products use glycine or its derivatives, such as the production of rubber sponge products, fertilizers, metal complexants.[11]

File:Betain-Glycine.pngZwitterionic salts of glycine at neutral pH

### Chemical feedstock

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Glycine is an intermediate in the synthesis of a variety of chemical products. It is used in the manufacture of the herbicide Glyphosate. Glyphosate (N-(phosphonomethyl) glycine) is a non-selective systemic herbicide used to kill weeds, especially perennials and broadcast or used in the cut-stump treatment as a forestry herbicide. Initially, Glyphosate was sold only by Monsanto under the Monsanto tradename Roundup, but is no longer under patent.

## Presence in space

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The detection of glycine in the interstellar medium has been debated.[12] In 2008, the glycine-like molecule aminoacetonitrile was discovered in the Large Molecule Heimat, a giant gas cloud near the galactic center in the constellation Sagittarius by the Max Planck Institute for Radio Astronomy.[13] In 2009, glycine sampled in 2004 from comet Wild 2 by the NASA spacecraft Stardust was confirmed, the first discovery of extraterrestrial glycine. That mission's results bolstered the theory of panspermia, which claims that the "seeds" of life are widespread throughout the universe.[14]

## See also

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* Trimethylglycine

## References

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1. ↑ Template:Merck11th.
2. ↑ Template:IUPAC-IUB amino acids 1983.
3. ↑ R.H.A. Plimmer (1912) [1908]. R.H.A. Plimmer & F.G. Hopkins, ed. The chemical composition of the proteins. Monographs on biochemistry. Part I. Analysis (2nd ed.). London: Longmans, Green and Co. p. 82. Retrieved January 18, 2010.
4. ↑ Template:OrgSynth.
5. ↑ Karlheinz Drauz, Ian Grayson, Axel Kleemann, Hans-Peter Krimmer, Wolfgang Leuchtenberger, Christoph Weckbecker “Amino Acids” in Ullmann's Encyclopedia of Industrial Chemistry 2007, Wiley-VCH, Weinheim. doi:10.1002/14356007.a02_057.pub2
6. ↑ 6.0 6.1 http://www.usitc.gov/trade_remedy/731_ad_701_cvd/investigations/2007/glycine_from_india_japan_korea/preliminary/DOC/Glycine Conference (prelim).wpd
7. ↑ U.S. International Trade Commission, "Glycine From China." Investigation No. 731-TA-718 (Second Review), Publication No. 3810, October 2005
8. ↑ 8.0 8.1 8.2 8.3 8.4 8.5 8.6 Template:Lehninger4th.
9. ↑ "Safety (MSDS) data for glycine". The Physical and Theoretical Chemistry Laboratory Oxford University. 2005. Retrieved 2006-11-01.
10. ↑ http://hotdocs.usitc.gov/docs/pubs/701_731/pub3921.pdf
11. ↑ "Notice of Preliminary Determination of Sales at Less Than Fair Value: Glycine From India" Federal Register 72 (7 November 2007): 62827.
12. ↑ Snyder LE, Lovas FJ, Hollis JM; et al. (2005). "A rigorous attempt to verify interstellar glycine". Astrophys J. 619 (2): 914–930. doi:10.1086/426677.CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
13. ↑ Staff. "Organic Molecule, Amino Acid-Like, Found In Constellation Sagittarius 27 March 2008 - Science Daily". Retrieved 2008-09-16.
14. ↑ Reuters (18 August 2009). "Building block of life found on comet - Thomson Reuters 2009". Retrieved 2009-08-18.

## Further reading

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On attempts to detect glycine in interstellar medium

* Kuan YJ, Charnley SB, Huang HC; et al. (2003). "Interstellar glycine". Astrophys J. 593 (2): 848–867. doi:10.1086/375637.CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
* Rachel Nowak. "Amino acid found in deep space - 18 July 2002 - New Scientist". Retrieved 2007-07-01.

## External links

[edit | edit source]

* Glycine at PDRHealth.com
* Glycine cleavage system
* Glycine Therapy - A New Direction for Schizophrenia Treatment?
* "Organic Molecule, Amino Acid-Like, Found In Constellation Sagittarius". ScienceDaily. 27 March 2008.
* Guochuan E. Tsai (1 December 2008). "A New Class of Antipsychotic Drugs: Enhancing Neurotransmission Mediated by NMDA Receptors". Psychiatric Times. 25 (14).
* ChemSub Online (Glycine).
* NASA scientists have discovered glycine, a fundamental building block of life, in samples of comet Wild 2 returned by NASA's Stardust spacecraft.

Template:Biochemical families Alanine (dp) | Arginine (dp) | Asparagine (dp) | Aspartic acid (dp) | Cysteine (dp) | Glutamic acid (dp) | Glutamine (dp) | Glycine (dp) | Histidine (dp) | Isoleucine (dp) | Leucine (dp) | Lysine (dp) | Methionine (dp) | Phenylalanine (dp) | Proline (dp) | Serine (dp) | Threonine (dp) | Tryptophan (dp) | Tyrosine (dp) | Valine (dp)

Template:Amino acid metabolism intermediates

* v
* t
* e

Neurotransmitters

Amino acid-derived|

* Major excitatory/inhibitory systems: Glutamate system: Agmatine
* Aspartic acid (aspartate)
* Cycloserine
* Glutamic acid (glutamate)
* Glutathione
* Glycine
* GSNO
* GSSG
* Kynurenic acid
* NAA
* NAAG
* Proline
* Serine; GABA system: GABA
* GABOB
* GHB; Glycine system: α-Alanine
* β-Alanine
* Glycine
* Hypotaurine
* Proline
* Sarcosine
* Serine
* Taurine; GHB system: GHB
* T-HCA (GHC)

* Biogenic amines: Monoamines: 6-OHM
* Dopamine
* Epinephrine (adrenaline)
* NAS (normelatonin)
* Norepinephrine (noradrenaline)
* Serotonin (5-HT); Trace amines: 3-Iodothyronamine
* N-Methylphenethylamine
* N-Methyltryptamine
* m-Octopamine
* p-Octopamine
* Phenylethanolamine
* Phenethylamine
* Synephrine
* Tryptamine
* m-Tyramine
* p-Tyramine; Others: Histamine

* Neuropeptides: See here instead.

Lipid-derived|

* Endocannabinoids: 2-AG
* 2-AGE (noladin ether)
* 2-ALPI
* 2-OG
* AA-5-HT
* Anandamide (AEA)
* DEA
* LPI
* NADA
* NAGly
* OEA
* Oleamide
* PEA
* RVD-Hpα
* SEA
* Virodhamine (O-AEA)

* Neurosteroids: See here instead.

Nucleobase-derived|

* Nucleosides: Adenosine system: Adenosine
* ADP
* AMP
* ATP

Vitamin-derived|

* Cholinergic system: Acetylcholine

Miscellaneous|

* Gasotransmitters: Carbon monoxide (CO)
* Hydrogen sulfide (H2S)
* Nitric oxide (NO); Candidates: Acetaldehyde
* Ammonia (NH3)
* Carbonyl sulfide (COS)
* Nitrous oxide (N2O)
* Sulfur dioxide (SO2)

* v
* t
* e

Glycine receptor modulators

Receptor
(ligands)|

| GlyR|

* Agonists: β-Alanine
* β-ABA (BABA)
* β-AIBA
* Caesium
* D-Alanine
* D-Serine
* GABA
* Glycine
* Hypotaurine
* Ivermectin
* L-Alanine
* L-Proline
* L-Serine
* L-Threonine
* MDL-27531
* Milacemide
* Picolinic acid
* Propofol
* Quisqualamine
* Sarcosine
* Taurine

* Positive modulators: Alcohols (e.g., brometone, chlorobutanol (chloretone), ethanol (alcohol), tert-butanol (2M2P), tribromoethanol, trichloroethanol, trifluoroethanol)
* Alkylbenzene sulfonate
* Anandamide
* Barbiturates (e.g., pentobarbital, sodium thiopental)
* Chlormethiazole
* D12-116
* Dihydropyridines (e.g., nicardipine)
* Etomidate
* Ginseng constituents (e.g., ginsenosides (e.g., ginsenoside-Rf))
* Glutamic acid (glutamate)
* Ivermectin
* Ketamine
* Neuroactive steroids (e.g., alfaxolone, pregnenolone (eltanolone), pregnenolone acetate, minaxolone, ORG-20599)
* Nitrous oxide
* Penicillin G
* Propofol
* Tamoxifen
* Tetrahydrocannabinol
* Triclofos
* Tropeines (e.g., atropine, bemesetron, cocaine, LY-278584, tropisetron, zatosetron)
* Volatiles/gases (e.g., chloral hydrate, chloroform, desflurane, diethyl ether (ether), enflurane, halothane, isoflurane, methoxyflurane, sevoflurane, toluene, trichloroethane (methyl chloroform), trichloroethylene)
* Xenon
* Zinc

* Antagonists: 2-Aminostrychnine
* 2-Nitrostrychnine
* 4-Phenyl-4-formyl-N-methylpiperidine
* αEMBTL
* Bicuculline
* Brucine
* Cacotheline
* Caffeine
* Colchicine
* Colubrine
* Cyanotriphenylborate
* Dendrobine
* Diaboline
* Endocannabinoids (e.g., 2-AG, anandamide (AEA))
* Gaboxadol (THIP)
* Gelsemine
* iso-THAZ
* Isobutyric acid
* Isonipecotic acid
* Isostrychnine
* Laudanosine
* N-Methylbicuculline
* N-Methylstrychnine
* N,N-Dimethylmuscimol
* Nipecotic acid
* Pitrazepin
* Pseudostrychnine
* Quinolines (e.g., 4-hydroxyquinoline, 4-hydroxyquinoline-3-carboxylic acid, 5,7-CIQA, 7-CIQ, 7-TFQ, 7-TFQA)
* RU-5135
* Sinomenine
* Strychnine
* Thiocolchicoside
* Tutin

* Negative modulators: Amiloride
* Benzodiazepines (e.g., bromazepam, clonazepam, diazepam, flunitrazepam, flurazepam)
* Corymine
* Cyanotriphenylborate
* Daidzein
* Dihydropyridines (e.g., nicardipine, nifedipine, nitrendipine)
* Furosemide
* Genistein
* Ginkgo constituents (e.g., bilobalide, ginkgolides (e.g., ginkgolide A, ginkgolide B, ginkgolide C, ginkgolide J, ginkgolide M))
* Imipramine
* NBQX
* Neuroactive steroids (e.g., 3α-androsterone sulfate, 3β-androsterone sulfate, deoxycorticosterone, DHEA sulfate, pregnenolone sulfate, progesterone)
* Opioids (e.g., codeine, dextromethorphan, dextrorphan, levomethadone, levorphanol, morphine, oripavine, pethidine, thebaine)
* Picrotoxin (i.e., picrotin and picrotoxinin)
* PMBA
* Riluzole
* Tropeines (e.g., bemesetron, LY-278584, tropisetron, zatosetron)
* Verapamil
* Zinc

|

NMDAR|

* See here instead.

Transporter
(blockers)|

| GlyT1|

* ACPPB
* ALX-1393
* ALX-5407 (NFPS)
* AMG-747
* ASP2535
* BIIB-104 (PF-04958242)
* Bitopertin (RG1678/RO4917838)
* CP-802079
* Ethanol (alcohol)
* Glycyldodecylamide
* GSK1018921
* LY-2365109
* ORG-24598
* ORG-25935 (SCH-900435)
* PF-02545920
* PF-03463275
* Sarcosine
* SSR-103,800
* SSR-504,734

|

GlyT2|

* Amoxapine
* Ethanol (alcohol)
* NAGly
* Opiranserin (VVZ-149)
* ORG-25543
* VVZ-368

See also
Receptor/signaling modulators
GABA receptor modulators
GABAA receptor positive modulators
Ionotropic glutamate receptor modulators

bn:গ্লাইসিন zh-min-nan:Glycine ca:Glicina cs:Glycin da:Glycin de:Glycin el:Γλυκίνη eo:Glicino eu:Glizina fa:گلیسین ko:글리신 hr:Glicin id:Glisina it:Glicina he:גליצין lv:Glicīns lb:Glycin lt:Glicinas hu:Glicin mk:Глицин nl:Glycine (aminozuur) no:Glycin oc:Glicina sr:Глицин su:Glisin fi:Glysiini sv:Glycin te:గ్లైసీన్ uk:Гліцин vls:Glycine
*[CID]: Compound ID
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template
*[GlyR]: Glycine receptor
*[NMDAR]: N-Methyl-D-aspartate receptor
*[GlyT1]: Glycine transporter 1
*[GlyT2]: Glycine transporter 2