phe·​nyl·​al·​a·​nine | \ ˌfe-nᵊl-ˈa-lə-ˌnēn How to pronounce phenylalanine (audio) , ˌfē- \

Definition of phenylalanine

: 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 With this knowledge, the family started their child on treatment with a specialized diet including low levels of phenylalanine. Wendy Chung, Scientific American, 30 Apr. 2021 In the 1960s microbiologist Robert Guthrie developed a test for phenylketonuria (PKU), a genetic disorder that causes the amino acid phenylalanine to build up in the body. Tanya Lewis, Scientific American, 24 Dec. 2019 Aspartame does break down into methanol and phenylalanine. Kat Eschner, Smithsonian, 27 Jan. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'phenylalanine.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of phenylalanine

circa 1883, in the meaning defined above

History and Etymology for phenylalanine

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Time Traveler for phenylalanine

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The first known use of phenylalanine was circa 1883

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Cite this Entry

“Phenylalanine.” Dictionary, Merriam-Webster, Accessed 18 Oct. 2021.

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phe·​nyl·​al·​a·​nine | \ ˌfen-ᵊl-ˈal-ə-ˌnēn, ˌfēn- How to pronounce phenylalanine (audio) \

Medical Definition of phenylalanine

: 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

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