Alanine

Alanine
	Structural formula of the L-isomer
	Ball-and-stick model of the L-isomer
colspan=2 style="background:#f8eaba; border-top:2px solid transparent; border-bottom:2px solid transparent; text-align:center;" #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Names #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect.-	IUPAC name Alanine
	Other names 2-Aminopropanoic acid
ChEBI	CHEBI:16977 7px
ChEMBL	ChEMBL66693 7px
ChemSpider	64234 (D-isomer) 7px; 5735 (L-isomer) 7px; 582 (Racemic) 7px
EC-number	206-126-4
	InChI InChI=1S/C3H7NO2/c1-2(4)3(5)6/h2H,4H2,1H3,(H,5,6)/t2-/m1/s1 7px; Key: QNAYBMKLOCPYGJ-UWTATZPHSA-N 7px; InChI=1/C3H7NO2/c1-2(4)3(5)6/h2H,4H2,1H3,(H,5,6); Key: QNAYBMKLOCPYGJ-UHFFFAOYAA;
IUPHAR ligand	720
Jmol-3D images	Image; Image
KEGG	C01401 7px
PubChem	Template:Chembox PubChem/format
	SMILES Template:Chembox SMILES/format; Template:Chembox SMILES/format;
Molar mass	Lua error in Module:Math at line 495: attempt to index field 'ParserFunctions' (a nil value). g·mol−1
Appearance	white powder
Density	1.424 g/cm3
Melting point	Script error: No such module "convert". (sublimes)
Solubility in water	167.2 g/L (25 °C)
Acidity (pKa)	2.35 (carboxyl), 9.69 (amino)
colspan=2 style="background:#f8eaba; border-top:2px solid transparent; border-bottom:2px solid transparent; text-align:center;" #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Supplementary data page#REDIRECTmw:Help:Magic words#Other; This page is a soft redirect.- #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Structure and; properties #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Refractive index (n),; Dielectric constant (εr), etc. #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect.- #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Thermodynamic; data #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Phase behaviour; solid–liquid–gas #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect.- #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. Spectral data #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect. UV, IR, NMR, MS #REDIRECTmw:Help:Magic words#Other; This page is a soft redirect.-	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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	Infobox references

Template:Chembox UNII

Alanine (abbreviated as Ala or A)^[2] is an α-amino acid with the chemical formula CH₃CH(NH₂)COOH. The L-isomer is one of the 20 amino acids encoded by the genetic code. Its codons are GCU, GCC, GCA, and GCG. It is classified as a non-polar amino acid. L-Alanine is second only to leucine in rate of occurrence, accounting for 7.8% of the primary structure in a sample of 1,150 proteins.^[3] D-Alanine occurs in bacterial cell walls and in some peptide antibiotics.

Structure

The α-carbon atom of alanine is bound with a methyl group (-CH₃), making it one of the simplest α-amino acids with respect to molecular structure and also resulting in alanine's being classified as an aliphatic amino acid. The methyl group of alanine is non-reactive and is thus almost never directly involved in protein function.

Sources

Dietary sources

Alanine is a nonessential amino acid, meaning it can be manufactured by the human body, and does not need to be obtained directly through the diet. Alanine is found in a wide variety of foods, but is particularly concentrated in meats.

Good sources of alanine include

Animal sources: meat, seafood, caseinate, dairy products, eggs, fish, gelatin, lactalbumin
Vegetarian sources: beans, nuts, seeds, soy, whey, brewer's yeast, brown rice, bran, corn, legumes, whole grains.

Biosynthesis

Alanine can be manufactured in the body from pyruvate and branched chain amino acids such as valine, leucine, and isoleucine.

Alanine is most commonly produced by reductive amination of pyruvate. Because transamination reactions are readily reversible and pyruvate pervasive, alanine can be easily formed and thus has close links to metabolic pathways such as glycolysis, gluconeogenesis, and the citric acid cycle. It also arises together with lactate and generates glucose from protein via the alanine cycle.

Chemical synthesis

Racemic alanine can be prepared by the condensation of acetaldehyde with ammonium chloride in the presence of sodium cyanide by the Strecker reaction, or by the ammonolysis of 2-bromopropanoic acid:^[4]

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File:L-Alanine synthesis.svg

L-Alanine Synthesis.^[5]

Physiological function

Glucose–alanine cycle

Alanine plays a key role in glucose–alanine cycle between tissues and liver. In muscle and other tissues that degrade amino acids for fuel, amino groups are collected in the form of glutamate by transamination. Glutamate can then transfer its amino group through the action of alanine aminotransferase to pyruvate, a product of muscle glycolysis, forming alanine and α-ketoglutarate. The alanine formed is passed into the blood and transported to the liver. A reverse of the alanine aminotransferase reaction takes place in liver. Pyruvate regenerated forms glucose through gluconeogenesis, which returns to muscle through the circulation system. Glutamate in the liver enters mitochondria and degrades into ammonium ion through the action of glutamate dehydrogenase, which in turn participate in the urea cycle to form urea.^[6]

The glucose–alanine cycle enables pyruvate and glutamate to be removed from the muscle and find their way to the liver. Glucose is regenerated from pyruvate and then returned to muscle: the energetic burden of gluconeogenesis is thus imposed on the liver instead of the muscle. All available ATP in muscle is devoted to muscle contraction.^[6]

Link to hypertension

An international study led by Imperial College London found a correlation between high levels of alanine and higher blood pressure, energy intake, cholesterol levels, and body mass index.^[7]

File:Zwitterion-Alanine.png

(S)-Alanine (left) and (R)-alanine (right) in zwitterionic form at neutral pH

Link to diabetes

Alterations in the alanine cycle that increase the levels of serum alanine aminotransferase (ALT) is linked to the development of type II diabetes. With an elevated level of ALT the risk of developing type II diabetes increases.^[8]

Chemical properties

Free radical stability

The deamination of an alanine molecule produces a stable alkyl free radical, CH₃C^•HCOO⁻. Deamination can be induced in solid or aqueous alanine by radiation.^[9]

This property of alanine is used in dosimetric measurements in radiotherapy. When normal alanine is irradiated, the radiation causes certain alanine molecules to become free radicals, and, as these radicals are stable, the free radical content^{[citation needed]} can later be measured by electron paramagnetic resonance in order to find out how much radiation the alanine was exposed to. Radiotherapy treatment plans can be delivered in test mode to alanine pellets, which can then be measured to check that the intended pattern of radiation dose is correctly delivered by the treatment system.

References

^ Dawson, R.M.C., et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
^ "Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)", Pure Appl. Chem. 56 (5), 1984: 595–624, doi:10.1351/pac198456050595 .
^ Doolittle, R. F. (1989), "Redundancies in protein sequences", in Fasman, G. D., Prediction of Protein Structures and the Principles of Protein Conformation, New York: Plenum, pp. 599–623, ISBN 0-306-43131-9 .
^ Kendall, E. C.; McKenzie, B. F. (1929). "dl-Alanine". Org. Synth. 9: 4. ; Coll. Vol. 1, p. 21 .
^ http://drugsynthesis.blogspot.co.uk/2011/11/laboratory-synthesis-of-l-alanine.html
^ ^a ^b Nelson, David L.; Cox, Michael M. (2005), Principles of Biochemistry (4th ed.), New York: W. H. Freeman, pp. 684–85, ISBN 0-7167-4339-6 .
^ Highfield, Roger (2008-04-21), "'Metabolic fingerprint' linked to high blood pressure", Daily Telegraph .
^ "Elevated Alanine Aminotransferase Predicts New-Onset Type 2 Diabetes Independently of Classical Risk Factors, Metabolic Syndrome, and C-Reactive Protein in the West of Scotland Coronary Prevention Study".
^ Zagórski, Z. P.; Sehested, K. (1998), "Transients and stable radical from the deamination of α-alanine", J. Radioanal. Nucl. Chem. 232 (1–2): 139–41, doi:10.1007/BF02383729 .

External links

Alanine MS spectrum

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[1] Dawson, R.M.C., et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.

[2] "Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)", Pure Appl. Chem. 56 (5), 1984: 595–624, doi:10.1351/pac198456050595 .

[3] Doolittle, R. F. (1989), "Redundancies in protein sequences", in Fasman, G. D., Prediction of Protein Structures and the Principles of Protein Conformation, New York: Plenum, pp. 599–623, ISBN 0-306-43131-9 .

[4] Kendall, E. C.; McKenzie, B. F. (1929). "dl-Alanine". Org. Synth. 9: 4. ; Coll. Vol. 1, p. 21 .

[5] ttp://drugsynthesis.blogspot.co.uk/2011/11/laboratory-synthesis-of-l-alanine.html

[Lehninger-6] Nelson, David L.; Cox, Michael M. (2005), Principles of Biochemistry (4th ed.), New York: W. H. Freeman, pp. 684–85, ISBN 0-7167-4339-6 .

[7] Highfield, Roger (2008-04-21), "'Metabolic fingerprint' linked to high blood pressure", Daily Telegraph .

[8] "Elevated Alanine Aminotransferase Predicts New-Onset Type 2 Diabetes Independently of Classical Risk Factors, Metabolic Syndrome, and C-Reactive Protein in the West of Scotland Coronary Prevention Study".

[9] Zagórski, Z. P.; Sehested, K. (1998), "Transients and stable radical from the deamination of α-alanine", J. Radioanal. Nucl. Chem. 232 (1–2): 139–41, doi:10.1007/BF02383729 .

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