thréonine

Thréonine, more commonly spelled threonine in English, is an essential amino acid in humans and many other animals. It is known chemically as 2-amino-4-hydroxybutanoic acid and has the formula C4H9NO3. In proteins, threonine is found in the L-configuration, and its codons are ACN (ACU, ACC, ACA, ACG).

As an essential amino acid, threonine cannot be synthesized in sufficient amounts by adults and must be obtained from the diet. Dietary sources include meat, fish, dairy products, eggs, legumes, nuts, seeds, and grains. Adequate intake of threonine supports normal growth, tissue maintenance, and protein synthesis. It also contributes to the production of mucin, a glycoprotein component of mucus, and supports overall gut and immune function.

Threonine participates in several metabolic pathways. It can be degraded through routes that yield glycine and other metabolites, and via pathways that produce intermediates such as 2-oxobutyrate, which feed into broader metabolic networks. Because threonine is both a building block for proteins and a precursor to other biomolecules, balanced dietary intake is important for health.

In clinical contexts, threonine deficiency is uncommon with a varied diet but may occur in cases of malnutrition or certain metabolic disorders. Excess intake from supplements is generally well tolerated, though high levels may disrupt amino acid balance. Overall, threonine is a fundamental, protein-building amino acid with specific roles in structural proteins and gut-related biology.