methionine

American  

[me-thahy-uh-neen, -nin] / mɛˈθaɪ əˌnin, -nɪn /

noun

Biochemistry.

1. an amino acid, CH 3 SCH 2 CH 2 CH(NH2 )COOH, found in casein, wool, and other proteins or prepared synthetically: used as a supplement to a special diet in the prevention and treatment of certain liver diseases. Met; M

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methionine British  

/ mɛˈθaɪəˌniːn, -ˌnaɪn /

noun

1. an essential amino acid containing sulphur, which occurs in many proteins: important in methylating reactions

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methionine Scientific  

/ mə-thī′ə-nēn′ /

1. An essential amino acid. Chemical formula: C ₅ H ₁₁ NO ₂ S.

2. See more at amino acid

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Etymology

Origin of methionine

First recorded in 1925–30; blend of methyl and thionine ( def. )

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Example Sentences

See Examples For:

methionine

It’s naturally produced in our liver, kidneys and pancreas and comes from the amino acids arginine, glycine and methionine — the “building blocks of protein.”

From Los Angeles Times ● Oct. 19, 2026

“The answer may be: more methionine capacity, a reversion in polyamide spreads and another round of cost savings as the company adapts to intense competition and slow demand growth,” Bray says.

From The Wall Street Journal ● Aug. 10, 2026

They found that adding the amino acid methionine to the animals' diet protected them from wasting, blood-brain barrier problems, and death linked to inflammation.

From Science Daily ● Jun. 1, 2026

This points to methionine as a possible tool for infectious diseases and inflammatory conditions, especially in people with kidney disease, kidney failure, or those undergoing dialysis.

From Science Daily ● Jun. 1, 2026

Beans have both lysine and tryptophan, but not the amino acids cysteine and methionine, which are provided by maize.

From "1491" by Charles C. Mann

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