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'''Glycine''' (abbreviated as '''Gly''' or '''G''')<ref>{{cite web | author=IUPAC-IUBMB Joint Commission on Biochemical Nomenclature | title=Nomenclature and Symbolism for Amino Acids and Peptides | work=Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc | url=http://www.chem.qmul.ac.uk/iupac/AminoAcid/ | accessdate=2007-05-17}}</ref> is the [[organic compound]] with the [[chemical formula|formula]] NH<sub>2</sub>CH<sub>2</sub>COOH. It is the smallest of the 20 [[amino acid]]s commonly found in [[protein]]s, coded by [[codons]] GGU, GGC, GGA and GGG. Glycine is unique among the [[proteinogenic amino acid]]s in that it is not [[chirality (chemistry)|chiral]]. Most proteins contain only small quantities of glycine. A notable exception is [[collagen]], which contains about 35% glycine.<ref name=Nel127>Nelson, D. L. & Cox, M. M. (2005). ''Lehninger Principles of Biochemistry'', 4th Edition. New York: W. H. Freeman and Company, p. 127. ISBN 0-7167-4339-6.</ref> In its solid, i.e., crystallized, form, glycine is a free-flowing, sweet-tasting crystalline material.
+
'''Glycine''' (abbreviated as '''Gly''' or '''G''')<ref>{{cite web | author=IUPAC-IUBMB Joint Commission on Biochemical Nomenclature | title=Nomenclature and Symbolism for Amino Acids and Peptides | work=Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc | url=http://www.chem.qmul.ac.uk/iupac/AminoAcid/ | accessdate=2007-05-17}}</ref> is the [[organic compound]] with the [[chemical formula|formula]] NH<sub>2</sub>CH<sub>2</sub>COOH. It is a [[non-essential [[amino acid]] that is an inhibitory [[neurotransmitter]]in the [[spinal cord]], binding to receptor sites on [[alpha motor neurons]]
   
==Production==
 
Glycine is manufactured industrially, either by treating [[chloroacetic acid]] with [[ammonia]]:
 
   
  +
It is the smallest of the 20 [[amino acid]]s commonly found in [[protein]]s, coded by [[codons]] GGU, GGC, GGA and GGG. Glycine is unique among the [[proteinogenic amino acid]]s in that it is not [[chirality (chemistry)|chiral]]. Most proteins contain only small quantities of glycine. A notable exception is [[collagen]], which contains about 35% glycine.<ref name=Nel127>Nelson, D. L. & Cox, M. M. (2005). ''Lehninger Principles of Biochemistry'', 4th Edition. New York: W. H. Freeman and Company, p. 127. ISBN 0-7167-4339-6.</ref> In its solid, i.e., crystallized, form, glycine is a free-flowing, sweet-tasting crystalline material.
:ClCH<sub>2</sub>COOH + NH<sub>3</sub> → H<sub>2</sub>NCH<sub>2</sub>COOH + HCl
 
   
  +
==Etymology==
or via the [[Strecker amino acid synthesis]].
 
  +
Glycine comes from the Greek ''glykys'' (sweet) +''ine'' (indicating an organi compound)
 
There are two producers of glycine in the United States. Chattem Chemicals, Inc., purchased by [[Sun Pharmaceuticals|Sun Pharmaceutical]], Mumbai, India<ref>http://timesfreepress.com/news/2008/dec/03/chattanooga-mumbai-india-company-buys-chattem-chem/</ref> and GEO Specialty Chemicals, Inc., who purchased the glycine and [[naphthalene]] sulfonate production facilities of Dow/Hampshire Chemical Corp.<ref name=usitc3810>U.S. International Trade Commission, "Glycine From China." Investigation No. 731-TA-718 (Second Review), Publication No. 3810, October 2005</ref> <ref name=Ham110105>Nov. 1, 2005 Press Release [http://news.dow.com/dow_news/prodbus/2005/20051101e.htm]</ref>
 
   
 
==Biosynthesis==
 
==Biosynthesis==
Line 63: Line 60:
   
 
===As A Potential Antipsychotic===
 
===As A Potential Antipsychotic===
Dr. Daniel Javitt a clinical researcher had studied people who were addicted to PCP (angel dust) and Ketamine (special K) (Javitt, DC, Negative Schizophrenic Symptomatology and the Phencyclydine (PCP) Model of Schizophrenia, Hillside Journal of Psychiatry 1987 9:12-35. Their brains had been damaged by the use of this drug. In studies, it was found that their glutamate receptors had been damaged. Since use of PCP and ketamine creates psychosis similar to schizophrenia, it was hypothesized that giving glycine to people with schizophrenia would potentially reduce their psychotic symptoms. In a controlled study people with schizophrenia who were given glycine had their symptoms reduced in a measurable sense, primarily in the area of negative and cognitive symptoms when used as an adjunct to current antipsychotics. There have been some psychiatrists who have used it out of study as a primary antipsychotic with benefits on positive as well as negative and cognitive symptoms. Glycine's primary drawback is its required use in powdered format. However, as an NMDA receptor modulator, it is part of a class of antipsychotics in study that do not cause tardive dyskinesia or diabetes, the current long term side effects of dopaminergic antipsychotics as well as not creating extra pyramdial side effects (movement disorders), weight gain or sedation. These medications along with other new classes of medications in study may eventually replace the current antipsychotics which, from Thorazine to Abilify, have all been based on the dopamine hypothesis and in depleting the levels of dopamine create tardive dykinesia and other Parkinsonian movement disorders and potentially tardive psychosis which is still in study. Glycine, is part of a promising new class of treatment for schizophrenia that may promote a full recovery without debilitating physical side effects.
+
Dr. Daniel Javitt a clinical researcher had studied people who were addicted to [[PCP]] (angel dust) and [[Ketamine]] (special K) (Javitt, DC, Negative Schizophrenic Symptomatology and the Phencyclydine (PCP) Model of Schizophrenia, Hillside Journal of Psychiatry 1987 9:12-35. Their brains had been damaged by the use of this drug. In studies, it was found that their [[glutamate receptors]] had been damaged. Since use of PCP and ketamine creates psychosis similar to schizophrenia, it was hypothesized that giving glycine to people with [[schizophrenia]] would potentially reduce their psychotic symptoms. In a controlled study people with schizophrenia who were given glycine had their symptoms measurably reduced primarily in the area of negative and cognitive symptoms when used as an adjunct to current [[antipsychotics]]. There have been some psychiatrists who have used it out of study as a primary antipsychotic with benefits on positive as well as negative and cognitive symptoms. Glycine's primary drawback is its required use in powdered format. However, as an NMDA receptor modulator, it is part of a class of antipsychotics in study that do not cause [[tardive dyskinesia]] or [[diabetes]], the current long term side effects of dopaminergic antipsychotics as well as not creating [[extra pyramdial side effects]] (movement disorders), [[weight gain]] or [[sedation]]. These medications along with other new classes of medications in study may eventually replace the current antipsychotics which, from [[Thorazine]] to [[Abilify]], have all been based on the [[dopamine hypothesis]] and in depleting the levels of dopamine. They can create tardive dykinesia and other Parkinsonian movement disorders and potentially [[tardive psychosis]] which is still in study. Glycine, is part of a promising new class of treatment for schizophrenia that may promote a full recovery without debilitating physical side effects.
  +
  +
==See also==
  +
*[[Strychnine]]
   
 
==References==
 
==References==
 
{{reflist}}
 
{{reflist}}
   
  +
==Further reading==
 
* Dawson, R.M.C., Elliott, D.C., Elliott, W.H., and Jones, K.M., ''Data for Biochemical Research'' (3rd edition), pp. 1-31 (1986) ISBN 01-985-535-87
 
* Dawson, R.M.C., Elliott, D.C., Elliott, W.H., and Jones, K.M., ''Data for Biochemical Research'' (3rd edition), pp. 1-31 (1986) ISBN 01-985-535-87
   

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Glycine
Glycine
General
Systematic name ?
Other names ?
Molecular formula ?
SMILES ?
Molar mass ?.?? g/mol
Appearance ?
CAS number [?-?-?]
Properties
Density and phase ? g/cm³, ?
Solubility in water ? g/100 ml (?°C)
Melting point ?°C (? K)
Boiling point ?°C (? K)
Acidity (pKa) ?
Basicity (pKb) ?
Chiral rotation [α]D
Viscosity ? cP at ?°C
Structure
Molecular shape ?
Coordination
geometry
?
Crystal structure ?
Dipole moment ? D
Hazards
MSDS External MSDS
Main hazards ?
NFPA 704
Flash point ?°C
R/S statement R: ?
S: ?
RTECS number ?
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions ?
Other cations ?
Related ? ?
Related compounds ?
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references


Glycine (abbreviated as Gly or G)[1] is the organic compound with the formula NH2CH2COOH. It is a [[non-essential amino acid that is an inhibitory neurotransmitterin the spinal cord, binding to receptor sites on alpha motor neurons


It is the smallest of the 20 amino acids commonly found in proteins, coded by codons GGU, GGC, GGA and GGG. Glycine is unique among the proteinogenic amino acids in that it is not chiral. Most proteins contain only small quantities of glycine. A notable exception is collagen, which contains about 35% glycine.[2] In its solid, i.e., crystallized, form, glycine is a free-flowing, sweet-tasting crystalline material.

Etymology

Glycine comes from the Greek glykys (sweet) +ine (indicating an organi compound)

Biosynthesis

Glycine is not essential to the human diet, since 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 by removing one carbon atom; pyridoxal phosphate is also necessary:[3]

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:[3]

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

Degradation

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:[4]

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.[4]

In the third pathway of glycine degradation, glycine is converted to glyoxylate by D-amino acid oxidase. Glycoxylate is then oxidized by hepatic lactate dehydrogenase to oxalate in an NAD+-dependent reaction.[4]

Physiological function

As a biosynthetic intermediate

Glycine is a building block to numerous natural products. 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.[5]

As a neurotransmitter

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. The LD50 of glycine is 7930 mg/kg in rats (oral),[6] and it usually causes death by hyperexcitability.

As A Potential Antipsychotic

Dr. Daniel Javitt a clinical researcher had studied people who were addicted to PCP (angel dust) and Ketamine (special K) (Javitt, DC, Negative Schizophrenic Symptomatology and the Phencyclydine (PCP) Model of Schizophrenia, Hillside Journal of Psychiatry 1987 9:12-35. Their brains had been damaged by the use of this drug. In studies, it was found that their glutamate receptors had been damaged. Since use of PCP and ketamine creates psychosis similar to schizophrenia, it was hypothesized that giving glycine to people with schizophrenia would potentially reduce their psychotic symptoms. In a controlled study people with schizophrenia who were given glycine had their symptoms measurably reduced primarily in the area of negative and cognitive symptoms when used as an adjunct to current antipsychotics. There have been some psychiatrists who have used it out of study as a primary antipsychotic with benefits on positive as well as negative and cognitive symptoms. Glycine's primary drawback is its required use in powdered format. However, as an NMDA receptor modulator, it is part of a class of antipsychotics in study that do not cause tardive dyskinesia or diabetes, the current long term side effects of dopaminergic antipsychotics as well as not creating extra pyramdial side effects (movement disorders), weight gain or sedation. These medications along with other new classes of medications in study may eventually replace the current antipsychotics which, from Thorazine to Abilify, have all been based on the dopamine hypothesis and in depleting the levels of dopamine. They can create tardive dykinesia and other Parkinsonian movement disorders and potentially tardive psychosis which is still in study. Glycine, is part of a promising new class of treatment for schizophrenia that may promote a full recovery without debilitating physical side effects.

See also

References

  1. IUPAC-IUBMB Joint Commission on Biochemical Nomenclature. Nomenclature and Symbolism for Amino Acids and Peptides. Recommendations on Organic & Biochemical Nomenclature, Symbols & Terminology etc. URL accessed on 2007-05-17.
  2. Nelson, D. L. & Cox, M. M. (2005). Lehninger Principles of Biochemistry, 4th Edition. New York: W. H. Freeman and Company, p. 127. ISBN 0-7167-4339-6.
  3. 3.0 3.1 Nelson, D. L. & Cox, M. M. (2005). Lehninger Principles of Biochemistry, 4th Edition. New York: W. H. Freeman and Company, p. 844. ISBN 0-7167-4339-6.
  4. 4.0 4.1 4.2 Nelson, D. L. & Cox, M. M. (2005). Lehninger Principles of Biochemistry, 4th Edition. New York: W. H. Freeman and Company, pp. 675-677. ISBN 0-7167-4339-6.
  5. Nelson, D. L. & Cox, M. M. (2005). Lehninger Principles of Biochemistry, 4th Edition. New York: W. H. Freeman and Company, p. 854. ISBN 0-7167-4339-6.
  6. Safety (MSDS) data for glycine. The Physical and Theoretical Chemistry Laboratory Oxford University. URL accessed on 2006-11-01.

Further reading

  • Dawson, R.M.C., Elliott, D.C., Elliott, W.H., and Jones, K.M., Data for Biochemical Research (3rd edition), pp. 1-31 (1986) ISBN 01-985-535-87

External links


Amino acids

Alanine | Arginine | Asparagine | Aspartic acid | Cysteine | Glutamic acid | Glutamine | Glycine | Histidine | Isoleucine | Leucine | Lysine | Methionine | Phenylalanine | Proline | Serine | Threonine | Tryptophan | Tyrosine | Valine
Essential amino acid | Protein | Peptide | Genetic code


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