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Phenylalanine
Type of α-amino acid / From Wikipedia, the free encyclopedia
Phenylalanine (symbol Phe or F)[3] is an essential α-amino acid with the formula C
9H
11NO
2. It can be viewed as a benzyl group substituted for the methyl group of alanine, or a phenyl group in place of a terminal hydrogen of alanine. This essential amino acid is classified as neutral, and nonpolar because of the inert and hydrophobic nature of the benzyl side chain. The L-isomer is used to biochemically form proteins coded for by DNA. Phenylalanine is a precursor for tyrosine, the monoamine neurotransmitters dopamine, norepinephrine (noradrenaline), and epinephrine (adrenaline), and the biological pigment melanin. It is encoded by the messenger RNA codons UUU and UUC.
![]() Skeletal formula of L-phenylalanine | |||
![]() L-Phenylalanine at physiological pH | |||
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Names | |||
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Pronunciation | US: /ˌfɛnəlˈæləniːn/; UK: /ˌfiːnaɪl-/ | ||
IUPAC name
Phenylalanine | |||
Systematic IUPAC name
(S)-2-Amino-3-phenylpropanoic acid | |||
Identifiers | |||
3D model (JSmol) |
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ChEBI |
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ChEMBL |
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ChemSpider | |||
DrugBank |
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ECHA InfoCard | 100.000.517 ![]() | ||
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KEGG |
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PubChem CID |
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UNII |
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CompTox Dashboard (EPA) |
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Properties | |||
C9H11NO2 | |||
Molar mass | 165.192 g·mol−1 | ||
9.97 g/L at 0 °C 14.11 g/L at 25 °C | |||
Acidity (pKa) | 1.83 (carboxyl), 9.13 (amino)[2] | ||
Hazards | |||
NFPA 704 (fire diamond) | |||
Supplementary data page | |||
Phenylalanine (data page) | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Phenylalanine is found naturally in the milk of mammals. It is used in the manufacture of food and drink products and sold as a nutritional supplement as it is a direct precursor to the neuromodulator phenethylamine. As an essential amino acid, phenylalanine is not synthesized de novo in humans and other animals, who must ingest phenylalanine or phenylalanine-containing proteins.
The one-letter symbol F was assigned to phenylalanine for its phonetic similarity.[4]