Threonine

Threonine

Skeletal formula of L-threonine
Ball-and-stick model Space-filling model
Names
IUPAC name Threonine
Other names 2-Amino-3-hydroxybutanoic acid
Identifiers
CAS Number	L: 72-19-5 Y D/L: 80-68-2 Y
3D model ( JSmol )	L: Interactive image L Zwitterion: Interactive image
ChEBI	L: CHEBI:16857 Y
ChEMBL	L: ChEMBL291747 Y
ChemSpider	L: 6051 Y
DrugBank	L: DB00156 Y
ECHA InfoCard	100.000.704
EC Number	L: 200-774-1
IUPHAR/BPS	L: 4785
KEGG	L: D00041
PubChem CID	L: 6288
UNII	L: 2ZD004190S Y D/L: TFM6DU5S6A Y
CompTox Dashboard (EPA)	L: DTXSID70893087 DTXSID2046412, DTXSID70893087
InChI InChI=1S/C4H9NO3/c1-2(6)3(5)4(7)8/h2-3,6H,5H2,1H3,(H,7,8)/t2-,3+/m1/s1 Y Key: AYFVYJQAPQTCCC-GBXIJSLDSA-N Y D/L: Key: AYFVYJQAPQTCCC-FGNFWGHYNA-N
SMILES L: C[C@H]([C@@H](C(=O)O)N)O L Zwitterion: C[C@H]([C@@H](C(=O)[O-])[NH3+])O
Properties
Chemical formula	C4H9NO3
Molar mass	119.120 g·mol−1
Solubility in water	(H2O, g/dl) 10.6(30°),14.1(52°),19.0(61°)
Acidity (pKa)	2.63 (carboxyl), 10.43 (amino)[1]
Supplementary data page
Threonine (data page)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Threonine (symbol Thr or T)

Threonine sidechains are often hydrogen bonded; the most common small motifs formed are based on interactions with

Stereoisomers

L-threonine (2S,3R) and D-threonine (2R,3S)

L-allothreonine (2S,3S) and D-allothreonine (2R,3R)

Threonine is one of two proteinogenic amino acids with two

As an essential amino acid, threonine is not synthesized in humans, and needs to be present in proteins in the diet. Adult humans require about 20 mg/kg body weight/day.[8] In plants and microorganisms, threonine is synthesized from aspartic acid via α-aspartyl-semialdehyde and homoserine. Homoserine undergoes O-phosphorylation; this phosphate ester undergoes hydrolysis concomitant with relocation of the OH group.^[9] Enzymes involved in a typical biosynthesis of threonine include:

1. aspartokinase
2. β-aspartate semialdehyde dehydrogenase
3. homoserine dehydrogenase
4. homoserine kinase
5. threonine synthase.

Metabolism

Threonine is metabolized in at least three ways:

• In many animals it is converted to
  threonine dehydrogenase. An intermediate in this pathway can undergo thiolysis with CoA to produce acetyl-CoA and glycine
  .
• In humans the gene for threonine dehydrogenase is an inactive
  α-ketobutyrate. The mechanism of the first step is analogous to that catalyzed by serine dehydratase, and the serine and threonine dehydratase reactions are probably catalyzed by the same enzyme.^[11]
• In many organisms it is
  (R)-1-aminopropan-2-ol for incorporation into the vitamin's sidechain.^[12]
• Threonine is used to synthesize glycine during the endogenous production of L-carnitine in the brain and liver of rats.[13]^[14]

Metabolic diseases

This section does not cite any sources. Please help improve this section by adding citations to reliable sources. Unsourced material may be challenged and removed. (November 2023) (Learn how and when to remove this template message)

The degradation of threonine is impaired in the following metabolic diseases:

• Combined malonic and methylmalonic aciduria (CMAMMA)^[15]
• Methylmalonic acidemia^[15]
• Propionic acidemia^[16]

Research of Threonine as a Dietary Supplement in Animals

Effects of threonine dietary supplementation have been researched in broilers.^[17]

An essential amino acid, threonine is involved in the metabolism of fats, the creation of proteins, the proliferation and differentiation of

Foods high in threonine include cottage cheese, poultry, fish, meat, lentils, black turtle bean^[19] and sesame seeds.^[20]