tryptophan

American  

[trip-tuh-fan] / ˈtrɪp təˌfæn /

Also tryptophane

noun

Biochemistry.

1. an essential amino acid, (C 8 H 6 N)CH 2 CH(NH2 )COOH, colorless, crystalline, and aromatic, released from proteins by tryptic digestion and a precursor of serotonin. Trp; W

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tryptophan British  

/ ˈtrɪptəˌfæn /

noun

1. an essential amino acid; a component of proteins necessary for growth

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tryptophan Scientific  

/ trĭp′tə-făn′ /

1. An essential amino acid. Chemical formula: C ₁₁ H ₁₂ N ₂ O ₂ .

2. See more at amino acid

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Etymology

Origin of tryptophan

1900–05; trypto- (irregular combining form representing Greek trīptós “rubbed”) + -phan(e) ( def. )

Explanation

Tryptophan is an amino acid that humans need in their diets in order to be healthy. Meat is known for providing lots of tryptophan. You may be familiar with tryptophan as the chemical present in turkey that is supposed to make people feel like taking a nap after their Thanksgiving feasts. In reality, scientists suspect that carbohydrates and alcohol — as well as overeating — are the true culprits in post-feast sleepiness. Tryptophan is important, though, since it helps our bodies synthesize the protein that we eat.

Example Sentences

See Examples For:

tryptophan

These markers include glucose, fats called triglycerides, and the protein tryptophan.

From Science Daily ● Mar. 15, 2026

Partly because I was exhausted from the tryptophan I had ingested with my turkey the day before and could not get out of bed.

From The Wall Street Journal ● Nov. 28, 2025

No—they’re football tryptophan, a snoozy bore to watch.

From The Wall Street Journal ● Nov. 24, 2025

Then, using mass spectrometry, they ran a screen to find the chemical identities of tryptophan metabolites in a gut sample, and identified three such metabolites that were significantly increased when given a tryptophan diet.

From Science Daily ● Mar. 13, 2024

Maize lacks digestible niacin, the amino acids lysine and tryptophan, necessary to make proteins and diets with too much maize can lead to protein deficiency and pellagra, a disease caused by lack of niacin.

From "1491" by Charles C. Mann