Phenylalanine

InChI=1S/C9H11NO2/c10-8(9(11)12)6-7-4-2-1-3-5-7/h1-5,8H,6,10H2,(H,11,12)/t8-/m0/s1
Key: COLNVLDHVKWLRT-QMMMGPOBSA-N
L: Key: COLNVLDHVKWLRT-QMMMGPOBBC
D/L: Key: COLNVLDHVKWLRT-UHFFFAOYSA-N
D: Key: COLNVLDHVKWLRT-MRVPVSSYSA-N

SMILES

L: c1ccc(cc1)C[C@@H](C(=O)O)N
D: c1ccc(cc1)C[C@H](C(=O)O)N
L Zwitterion: [NH3+][C@@H](CC1=CC=CC=C1)C([O-])=O
D Zwitterion: [NH3+][C@H](CC1=CC=CC=C1)C([O-])=O

Properties

Chemical formula

C₉H₁₁NO₂Molar mass165.192 g·mol

Solubility in water

9.97 g/L at 0 °C

14.11 g/L at 25 °C
21.87 g/L at 50 °C
37.08 g/L at 75 °C
68.9 g/L at 100 °C

Acidity (pK_a) 1.83 (carboxyl), 9.13 (amino) Hazards NFPA 704 (fire diamond)

2

1

0

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).

Phenylalanine (symbol Phe or F) is an α-amino acid with the formulaC
₉H
₁₁NO
₂. It is one of the four aromatic amino acids and the 21 proteinogenic amino acids common to all life forms. It is also one of the nine essential amino acids. This means that humans and other animals cannot biosynthesize phenylalanine, so they must obtain it from dietary sources such as meat, dairy, eggs, and legumes. 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.

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. It 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. The one-letter symbol F was assigned to phenylalanine for its phonetic similarity.