Alanine 63539 219478908 2008-06-15T12:38:16Z SieBot 4005189 robot Modifying: [[id:Alanin]] {{NatOrganicBox | image= [[Image:Alanin - Alanine.svg|150px]] [[Image:L-alanine-3D-sticks.png|140px]] Chemical structure of <small>L</small>-alanine | name=(''S'')-2-aminopropanoic acid | PubChem = 5950 | CAS = 56-41-7 | SMILES = C[C@H](N)C(O)=O | C=3 | H=7 | N=1 | O=2 | mass=89.1 g/mol }} '''Alanine''' (abbreviated as '''Ala''' or '''A''')<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 an α-[[amino acid]] with the [[chemical formula]] HO<sub>2</sub>CCH(NH<sub>2</sub>)CH<sub>3</sub>. The L-isomer is one of the 20 [[proteinogenic amino acid]]s, i.e. the building blocks of [[protein]]s. Its codons are GCU, GCC, GCA, and GCG. It is classified as a non-polar amino acid. L-alanine is second only to [[leucine]], accounting for 7.8% of the [[primary structure]] in a sample of 1,150 [[proteins]].<ref>Doolittle, R. F.; & Fasman G.D. (ed.) (1989). "Redundancies in protein sequences" in ''Prediction of Protein Structures and the Principles of Protein Conformation''. New York: Plenum Press, pp. 599-623.</ref> D-alanine occurs in bacterial cell walls and in some peptide antibiotics. ==Structure== The [[alpha carbon|α-carbon]] atom of alanine is bound with a [[methyl]] group (-CH<sub>3</sub>), making it one of the simplest α-amino acids with respect to molecular structure and also resulting in alanine being classified as an [[aliphatic compound|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 [[essential amino acid|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 [[BCAA|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 via the condensation of [[acetaldehyde]] with [[ammonium chloride]] in the presence of [[potassium cyanide]] by the [[Strecker amino acid synthesis|Strecker reaction]].<ref> Kendall, E. C.; McKenzie, B. F. “dl-Alanine” Organic Syntheses, Collected Volume 1, p.21 (1941). http://www.orgsyn.org/orgsyn/pdfs/CV1P0021.pdf</ref> ==Physiological function== ===As a carrier of ammonia and of the carbon skeleton of pyruvate in 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 [[alpha-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]].<ref name=Nel684>Nelson, D. L. & Cox, M. M. (2005). ''Lehninger Principles of Biochemistry'', 4th Edition. New York: W. H. Freeman and Company, pp. 684-685. ISBN 0-7167-4339-6.</ref> Glucose-alanine cycle enables pyruvate and glutamate to be removed from muscle and find their ways to liver. Glucose is able to be regenerated from pyruvate and returned to muscle. The energetic burden of gluconeogenesis is thus imposed on the liver instead of the muscle. All available [[Adenosine triphosphate|ATP]] in muscle is devoted to muscle contraction.<ref name=Nel684/> ===Link to hypertension=== An international study led by [[Imperial College London]] found that people with high levels of alanine have higher blood pressure, energy intake, cholesterol levels, and body mass index.<ref>[http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2008/04/21/sciblood121.xml 'Metabolic fingerprint' linked to high blood pressure - Telegraph<!-- Bot generated title -->]</ref> ==Chemical properties== ===Free radical stability=== The deamination of an alanine molecule produces a stable alkyl [[Radical (chemistry)|free radical]], CH<sub>3</sub>C<sup>•</sup>HCOO<sup>–</sup>. Deamination can be induced in solid or aqueous alanine by radiation.<ref>Journal of Radioanalytical and Nuclear Chemistry, 1998, 232(1-2), pp. 139-141. DOI 10.1007/BF02383729 http://www.springerlink.com/content/j050542210k251ru/</ref> This property of alanine is used in [[dosimetry|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{{Fact|date=March 2008}} can later be measured in order to find out how much radiation the alanine was exposed to. In this way, one can be assured that complex radiotherapy treatment plans will deliver the intended pattern of radiation dose. ==References== {{reflist}} ==See also== *[[carbamic acid]] *[[glycine]] == External links == *[http://www.compchemwiki.org/index.php?title=Alanine Computational Chemistry Wiki] {{AminoAcids}} [[Category:Proteinogenic amino acids]] [[Category:Glucogenic amino acids]] [[bn:অ্যালানিন]] [[ca:Alanina]] [[cs:Alanin]] [[da:Alanin]] [[de:Alanin]] [[el:Αλανίνη]] [[es:Alanina]] [[eo:Alanino]] [[fr:Alanine]] [[gl:Alanina]] [[ko:알라닌]] [[hr:Alanin]] [[id:Alanin]] [[it:Alanina]] [[he:אלנין]] [[lv:Alanīns]] [[lb:Alanin]] [[lt:Alaninas]] [[hu:Alanin]] [[nl:Alanine]] [[ja:アラニン]] [[ps:آلانين]] [[pl:Alanina]] [[pt:Alanina]] [[ro:Alanină]] [[ru:Аланин]] [[sk:Alanín]] [[sr:Аланин]] [[su:Alanin]] [[fi:Alaniini]] [[sv:Alanin]] [[tr:Alanin]] [[uk:Аланін]] [[zh:丙氨酸]]