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methionine Line breaks: me¦thio|nine
Pronunciation: /mɪˈθʌɪəniːn/

Definition of methionine in English:


[mass noun] Biochemistry
A sulphur-containing amino acid which is a constituent of most proteins and is essential to the diet of vertebrates.
Example sentences
  • They fix nitrogen and so contain high quality protein, including the essential amino acids methionine and cystine.
  • The oxidation sites of alpha-crystallin are considered to be methionine, cysteine and tryptophan amino acid residues.
  • For example, eggs are high in alanine and methionine; whey protein is high in tryptophan and threonine.


1920s: from methyl + Greek theion 'sulphur'.

Definition of methionine in:

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