Phenylalanine 38001 225796458 2008-07-15T13:11:43Z Richerman 5318500 expanded the lead with some wording that may make it a bit more accessible to the layman :'''''Phe''' redirects here. For the BitTorrent feature, see [[PHE]]. For the constellation, see [[Phoenix (constellation)]].'' {{NatOrganicBox | image=<br>[[Image:L-phenylalanine-skeletal.png|180px]]<br><br>[[Image:L-phenylalanine-3D-sticks.png|160px]] | name=2-Amino-3-phenyl-propanoic acid | PubChem = 994 | CAS = 63-91-2 | SMILES = S=N[C@@H]<br>(Cc1ccccc1)C(O)=O | C=9 | H=11 | N=1 | O=2 | mass=165.19 g/mol }} '''Phenylalanine''' (abbreviated as '''Phe''' or '''F''')<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|formula]] HO<sub>2</sub>CCH(NH<sub>2</sub>)CH<sub>2</sub>C<sub>6</sub>H<sub>5</sub>, which is found naturally in the breast milk of mammals and in some plants and microorganisms. Manufactured forms are used in food and drink products and are also sold as nutritional supplements for their reputed [[analgesic]] and [[antidepressant]] effects. This [[essential amino acid]] is classified as [[nonpolar]] because of the [[hydrophobic]] nature of the [[benzyl]] side chain. The [[codons]] for <small>L</small>-phenylalanine are UUU and UUC. It is a white, powdery [[solid]]. <small>L</small>-Phenylalanine (LPA) is an electrically-neutral [[amino acid]], one of the twenty common amino acids used to biochemically form [[protein]]s, coded for by [[DNA]]. ==Biosynthesis== Breast [[milk]] from mammals is rich in phenylalanine. It is also produced by plants and most microorganisms from [[Prephenic acid|prephenate]], an intermediate on the [[Shikimic acid|shikimate pathway]].<ref name=Nelson>Nelson, D. L.; Cox, M. M. "Lehninger, Principles of Biochemistry" 3rd Ed. Worth Publishing: New York, 2000. ISBN 1-57259-153-6.</ref> [[Image:Phenylalanine biosynthesis.png|500px]] Prephenate is [[Decarboxylation|decarboxylated]] with loss of the [[hydroxyl]] group to give phenylpyruvate. This species is [[Transamination|transaminated]] using [[Glutamic acid|glutamate]] as the nitrogen source to give phenylalanine and [[Ketoglutaric acid|α-ketoglutarate]]. ==Other biological roles== <small>L</small>-phenylalanine can also be converted into <small>L</small>-[[tyrosine]], another one of the DNA-encoded amino acids. <small>L</small>-tyrosine in turn is converted into [[L-DOPA]], which is further converted into [[dopamine]], [[norepinephrine]] (noradrenaline), and [[epinephrine]] (adrenaline) (the latter three are known as the [[catecholamines]]). Phenylalanine uses the same active transport channel as [[tryptophan]] to cross the [[blood-brain barrier]], and, in large quantities, interferes with the production of [[serotonin]]. [[Image:DLPA RXN.GIF]] [[Lignin]] is derived from phenylalanine and from [[tyrosine]]. Phenylalanine is converted to [[cinnamic acid]] by the enzyme phenylalanine ammonia lyase.<ref name=Nelson/> ===Phenylketonuria=== The genetic disorder [[phenylketonuria]] (PKU) is the inability to metabolize phenylalanine. Individuals with this disorder are known as "phenylketonurics" and must abstain from consumption of phenylalanine. This dietary restriction also applies to pregnant women with hyperphenylalanine (high levels of phenylalanine in blood) because they do not properly metabolize the amino acid phenylalanine. Persons suffering from PKU must monitor their intake of protein to control the buildup of phenylalanine as their bodies convert protein into its component amino acids. A non food source of phenylalanine is the artificial sweetener [[aspartame]]. This compound, sold under the trade names "Equal" and "NutraSweet", is metabolized by the body into several chemical byproducts including phenylalanine. The breakdown problems phenylketonurics have with protein and the attendant build up of phenylalanine in the body also occurs with the ingestion of aspartame, although to a lesser degree. Accordingly, all products in Australia, the U.S. and Canada that contain aspartame must be labeled: "Phenylketonurics: Contains phenylalanine." In the UK, foods containing aspartame must carry ingredients panels that refer to the presence of 'aspartame or E951',<ref>[http://www.food.gov.uk/safereating/chemsafe/additivesbranch/sweeteners/55174#h_4 Aspartame], Food Standards Agency</ref> and they must be labeled with a warning "Contains a source of phenylalanine". These warnings are specifically placed to aid individuals who suffer from PKU so that they can avoid such foods. Geneticists have recently sequenced the genome of [[macaques]]. Their investigations have found "some instances where the normal form of the macaque protein looks like the diseased human protein" including markers for PKU.<ref>[http://news.bbc.co.uk/2/hi/science/nature/6550865.stm Scientists decode macaque genome], ''BBC News'', 13 April 2007</ref> ==<small>D</small>- and <small>DL</small>-phenylalanine== The unnatural [[stereoisomer]] <small>D</small>-phenylalanine (DPA) can be produced by conventional [[organic synthesis]], either as a single [[enantiomer]] or as a component of the [[racemic]] mixture. It does not participate in [[protein biosynthesis]] although it is found in proteins in small amounts - particularly aged proteins and food proteins that have been [[processed food|processed]]. The biological functions of <small>D</small>-amino acids remain unclear although some, such as <small>D</small>-phenylalanine, may have [[pharmacological activity]]. <small>DL</small>-Phenylalanine is marketed as a nutritional supplement for its supposed [[analgesic]] and [[antidepressant]] activities. The reputed analgesic activity of DL-phenylalanine may be explained by the possible blockage by <small>D</small>-phenylalanine of [[enkephalin]] [[degradation]] by the [[enzyme]] [[carboxypeptidase A]].<ref>Christianson DW, Mangani S, Shoham G, Lipscomb WN. "Binding of D-phenylalanine and D-tyrosine to carboxypeptidase A." ''Journal of Biological Chemistry'' 1989 Aug 5;264(22):12849-53. PMID: 2568989.</ref> The mechanism of <small>DL</small>-phenylalanine's supposed antidepressant activity may be accounted for by the [[protein precursor|precursor]] role of <small>L</small>-phenylalanine in the synthesis of the [[neurotransmitters]], [[norepinephrine]] and [[dopamine]]. Elevated brain levels of norepinephrine and dopamine are thought to have an antidepressant effect.{{Fact|date=February 2008}} Following ingestion,<small>D</small>-Phenylalanine is absorbed from the small intestine and transported to the liver via the [[portal circulation]]. A small amount of <small>D</small>-phenylalanine appears to be converted to <small>L</small>-phenylalanine. <small>D</small>-Phenylalanine is distributed to the various tissues of the body via the [[systemic circulation]]. It appears to cross the [[blood-brain barrier]] less efficienciently than <small>L</small>-phenylalanine, and so a small amount of an ingested dose of <small>D</small>-phenylalanine is not absorbed but excreted in the [[urine]]. ==History== The genetic [[codon]] for phenylalanine was first discovered by [[Marshall W. Nirenberg]] in 1959. He showed that by using ''m''-[[RNA]] to insert multiple [[uracil]] repeats into the bacterium ''E. coli'', the bacterium produced a new protein consisting solely of repeated phenylalanine amino acids. This discovery lead to the determination of the relationship between RNA and amino acids, which was foundational to the understanding of the [[Genetic Code]]. ==References== <references/> ==External links== *[http://www.chem.qmul.ac.uk/iubmb/enzyme/reaction/AminoAcid/PheTyr.html Phenylalanine and tyrosine biosynthesis] *[http://www.compchemwiki.org/index.php?title=Phenylalanine Computational Chemistry Wiki] *[http://www.nitrogenorder.org/molweek/aug2005/21aug05.shtml Nitrogen Order's Molecule of the Week] *[http://www.biopsychiatry.com/dl-phenylalanine.html DL-phenylalanine versus imipramine in depression] {{AminoAcids}} [[Category:Proteinogenic amino acids]] [[Category:Glucogenic amino acids]] [[Category:Ketogenic amino acids]] [[Category:Aromatic amino acids]] [[Category:Essential amino acids]] [[ar:فينيل ألانين]] [[bg:Фенилаланин]] [[ca:Fenilalanina]] [[cs:Fenylalanin]] [[da:Fenylalanin]] [[de:Phenylalanin]] [[es:Fenilalanina]] [[eo:Fenilalanino]] [[fr:Phénylalanine]] [[ko:페닐알라닌]] [[hr:Fenilalanin]] [[id:Fenilalanin]] [[it:Fenilalanina]] [[he:פנילאלנין]] [[lv:Fenilalanīns]] [[lb:Phenylalanin]] [[lt:Fenilalaninas]] [[hu:Fenilalanin]] [[nl:Fenylalanine]] [[ja:フェニルアラニン]] [[no:Fenylalanin]] [[pl:Fenyloalanina]] [[pt:Fenilalanina]] [[ru:Фенилаланин]] [[sr:Фенилаланин]] [[fi:Fenyylialaniini]] [[sv:Fenylalanin]] [[tr:Fenilalanin]] [[uk:Фенілаланін]] [[zh:苯丙氨酸]]