View source for Phenylalanine

{{redirect|Phe|the BitTorrent feature|BitTorrent protocol encryption|the constellation|Phoenix (constellation)}}
{{chembox
| verifiedrevid = 375351520
| ImageFile = Phenylalanin_-_Phenylalanine.svg
| ImageSize = 180px
| ImageName = Skeletal formula
| ImageFile1 = L-phenylalanine-3D-balls.png
| ImageSize1 = 180px
| ImageName1 = Ball-and-stick model
| IUPACName = Phenylalanine
| OtherNames = 2-Amino-3-phenylpropanoic acid
| Section1 = {{Chembox Identifiers
| CASNo = 150-30-1
| CASNo_Comment = (DL)
|  CASNo_Ref = {{cascite}}
| CASNo2 = 63-91-2
| CASNo2_Comment = (L) <!-- also CAS verified -->
| PubChem = 994
| ChemSpiderID = 5910
| SMILES = C1=CC=C(C=C1)CC(C(=O)O)N}}
| Section2 = {{Chembox Properties
| C=9 | H=11 | O=2 | N=1
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| Section3 = {{Chembox Hazards
| MainHazards = 
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{{drugbox 
|IUPAC_name=(2S)-2-amino-3-phenylpropanoic acid 
|image={{PAGENAME}}.png 
|CAS_number=63-91-2 
|ATC_prefix= 
|ATC_suffix= 
|ATC_supplemental= 
|PubChem=994 
|DrugBank=DB00120 
|chemical_formula=C<sub>9</sub>H<sub>11</sub>NO<sub>2</sub> 
|molecular_weight= 
|bioavailability= 
|protein_bound= 
|metabolism= 
|elimination_half-life= 
|excretion= 
|pregnancy_AU=<!-- A / B1 / B2 / B3 / C / D / X --> 
|pregnancy_US=<!-- A / B / C / D / X --> 
|pregnancy_category= 
|legal_AU=<!-- Unscheduled / S2 / S4 / S8 --> 
|legal_UK=<!-- GSL / P / POM / CD --> 
|legal_US=<!-- OTC / Rx-only --> 
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|routes_of_administration=}}

'''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>. This [[essential amino acid]] is classified as [[nonpolar]] because of the [[hydrophobic]] nature of the [[benzyl]] side chain.  <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]]. The [[codons]] for <small>L</small>-phenylalanine are UUU and UUC. Phenylalanine is a precursor for [[tyrosine]], the [[monoamine]] signaling molecules [[dopamine]], [[norepinephrine]] (noradrenaline), and [[epinephrine]] (adrenaline), and the skin [[pigment]] [[melanin]].

Phenylalanine is found naturally in the breast milk of mammals. It is used in the manufacture of food and drink products and sold as a nutritional supplement for its reputed [[analgesic]] and [[antidepressant]] effects.  It is a direct precursor to the neuromodulator [[phenylethylamine]], a commonly used dietary supplement.

==Other biological roles==
<small>L</small>-phenylalanine is biologically 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 Phenylalanine.GIF]]

===In plants===
Phenylalanine is the starting compound used in the [[flavonoid biosynthesis]]. [[Lignan]] is derived from phenylalanine and from [[tyrosine]]. Phenylalanine is converted to [[cinnamic acid]] by the enzyme phenylalanine ammonia lyase.<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>

==Phenylketonuria==
The genetic disorder [[phenylketonuria]] (PKU) is the inability to metabolize phenylalanine. Individuals with this disorder are known as "phenylketonurics" and must regulate their intake of phenylalanine. A (rare) "variant form" of phenylketonuria called [[hyperphenylalaninemia]] is caused by the inability to synthesize a [[coenzyme]] called [[biopterin]], which can be supplemented. Pregnant women with hyperphenylalaninemia may show similar symptoms of the disorder (high levels of phenylalanine in blood) but these indicators will usually disappear at the end of gestation. Individuals who cannot metabolize phenylalanine 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 ingredient 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 [[Phenylketonuria|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 [[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 (DLPA) 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. 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 efficiently 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 [[J. Heinrich Matthaei]] and [[Marshall W. Nirenberg]] in 1961. They showed that by using ''m''-[[RNA]] to insert multiple [[uracil]] repeats into the [[genome]] of the bacterium ''[[Escherichia coli|E. coli]]'', they could cause the bacterium to produce a polypeptide consisting solely of repeated phenylalanine amino acids. This discovery helped to establish the nature of the coding relationship that links information stored in [[genome|genomic]] nucleic acid with [[proteome|protein expression]] in the living cell.

==See also==
*[[Hyperphenylalanemia]]

==References==
{{reflist}}

==External links==
* [http://www.chemsynthesis.com/base/chemical-structure-453.html Phenylalanine at ChemSynthesis]
* [http://nutrient.javalime.com/nutrient.php/508 Food Sources of Phenylalanine]


{{AminoAcids}}
{{Amino acid metabolism intermediates}}
{{Analgesics}}
{{Antidepressants}}
{{Anxiolytics}}
{{Dopaminergics}}
{{Opioids}}
{{Phenethylamines}}

[[Category:Animal products]]
[[Category:Proteinogenic amino acids]]
[[Category:Glucogenic amino acids]]
[[Category:Ketogenic amino acids]]
[[Category:Aromatic amino acids]]
[[Category:Essential amino acids]]
[[Category:Enkephalinase inhibitors]]

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