noun[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
More 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:
- The US English dictionary