Threonine

Threonine (abbreviated Thr or T) is one of the twenty amino acids that make up proteins; its side chain is hydrophilic. It is encoded in the messenger RNA as ACU, ACC, ACA, or ACG.

L-threonine (levothreonine) is obtained almost preferably by a fermentation process by microorganisms (for example, genetically modified yeasts), although it can also be obtained by isolation from protein hydrolysates for pharmaceutical use.

History

Threonine was the last of the 20 common proteinogenic amino acids discovered in 1935 by American William Cumming Rose, collaborating with Curtis Meyer and William Rose. The amino acid threonine was named because it was similar in structure to threose, a four-carbon monosaccharide or carbohydrate with the molecular formula C
4H
8O
4.

Biosynthesis

As an essential amino acid, threonine is not synthesized in sufficient amounts in humans, so it must be ingested in the protein you eat. In plants and microorganisms, threonine is synthesized from aspartic acid by the α-Aspartyl-semialdehyde and homoserine pathway. Enzymes involved in its synthesis include: Threonine acts together with two other amino acids: methionine and aspartic acid, working to metabolize fats that are deposited in organs such as the liver.

• Asparto quinasa
• α-Aspartil-semialdhyde dehydrogenase
• Homoserina dehydrogenase
• Homoserina quinasa
• Treonina sintasa

Fonts

Foods rich in threonine include cottage cheese, poultry, fish, meat, lentils, and sesame seeds.