Phenylalanine

__**Formula:**__ C6H5CH2CH(NH2)COOH.
 * Phenylalanine** (abbreviated as **Phe** or **F**)

This essential amino acid is classified as nonpolar because of the hydrophobic nature of the benzyl side chain. L -Phenylalanine (LPA) is an electrically neutral amino acid, one of the twenty common amino acids used to biochemically form proteins, coded for by DNA. The codons for L -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.

Uses: 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.