phenylalanine

noun

phe·​nyl·​al·​a·​nine ˌfe-nᵊl-ˈa-lə-ˌnēn 

ˌfē-

: an essential amino acid C₉H₁₁NO₂ that is converted in the normal body to tyrosine

Examples of phenylalanine in a Sentence

Recent Examples on the Web

Tuna contains phenylalanine and tryptophan, both of which have been linked to antidepressant properties. —Lindsey Desoto, Rd, Health, 9 Sep. 2024

This causes phenylalanine to build up in the blood, leading to brain damage and intellectual disability.34 Tyrosine is made from phenylalanine, so people with PKU typically have low levels of tyrosine in their blood. —Lindsey Desoto, Rd, Ld, Health, 10 Aug. 2024

People with a rare genetic disorder called phenylketonuria (PKU) disease, a difficulty metabolizing phenylalanine, should avoid or restrict aspartame. —Anna Giorgi, Verywell Health, 8 Aug. 2024

Because aspartame contains the natural amino acid phenylalanine, people with phenylketonuria should avoid aspartame. —Trang Tran, Pharmd, Verywell Health, 26 July 2024

Word History

Etymology

International Scientific Vocabulary

First Known Use

circa 1883, in the meaning defined above

Medical Definition

phenylalanine

noun

phe·​nyl·​al·​a·​nine ˌfen-ᵊl-ˈal-ə-ˌnēn, ˌfēn- 

: an essential amino acid C₉H₁₁NO₂ that is obtained in its levorotatory L-form by the hydrolysis of proteins (as lactalbumin), that is essential in human nutrition, and that is converted in the normal body to tyrosine

—abbreviation Phe see phenylketonuria, phenylpyruvic acid