Phenylalanine (symbol Phe or F) is an α-amino acid.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 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 phenethylamine, a commonly used dietary supplement. As an essential amino acid, phenylalanine is not synthesized de novo in humans and other animals, who must ingest phenylalanine or phenylalanine-containing proteins.

Function:
1.L - phenylalanine are important food additives - sweetener Aspartame (Aspartame) of the main raw material, the human body essential amino acids in one of the pharmaceutical industry is mainly used for amino acid transfusion and amino acid drugs.
2.L - phenylalanine is human body can't synthesized a kind of essential amino acids. Food industry mainly for Food sweetener aspartame synthesis raw material;
3.Also can be used as nutritional supplement