Definition of methionine in English:

Share this entry


Pronunciation: /mɪˈθʌɪəniːn/


[mass noun] Biochemistry
A sulphur-containing amino acid which is a constituent of most proteins and is essential to the diet of vertebrates.
  • Chemical formula: CH3S(CH2)2CH(NH2)COOH.
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'.

For editors and proofreaders

Line breaks: me¦thio|nine

Share this entry

What do you find interesting about this word or phrase?

Comments that don't adhere to our Community Guidelines may be moderated or removed.