Definition of threonine in US English:



  • A hydrophilic amino acid which is a constituent of most proteins. It is an essential nutrient in the diet of vertebrates.

    Chemical formula: CH₃CH(OH)CH(NH₂)COOH

    • ‘The essential amino acids are histidine, tryptophan, threonine, valine, phenylalanine, leucine, methionine, lysine, and isoleusine.’
    • ‘In animal cells serine, threonine and tyrosine are the amino acids subject to phosphorylation.’
    • ‘The aspartate can be used as a precursor for the synthesis of other amino acids such as asparagine, threonine, isoleucine, leucine, valine, lysine, and methionine.’
    • ‘The amount of the amino acids threonine, proline and histidine were also increased in roots of slag-cultivated maize plants.’
    • ‘Nitrogen limitation in plants could explain the use of the polar amino acids serine and threonine instead of nitrogen-containing asparagine as in P. falciparum.’


1930s: from threose (the name of a tetrose sugar) + -ine.