Threonine

Threonine
	Skeletal formula of L-threonine
Ball-and-stick model	Space-filling model
Names
	IUPAC name Threonine
	Systematic IUPAC name 2-Amino-3-hydroxybutanoic acid
Identifiers
CAS Number	L: 72-19-5 ; D/L: 80-68-2 ;
3D model (JSmol)	L: Interactive image; L Zwitterion: Interactive image;
ChEBI	L: CHEBI:16857 ;
ChEMBL	L: ChEMBL291747 ;
ChemSpider	L: 6051 ;
DrugBank	L: DB00156 ;
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 ; D/L: TFM6DU5S6A ;
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 Key: AYFVYJQAPQTCCC-GBXIJSLDSA-N ; 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)
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)^[2] is an amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated −NH⁺
₃ form when dissolved in water), a carboxyl group (which is in the deprotonated −COO⁻ form when dissolved in water), and a side chain containing a hydroxyl group, making it a polar, uncharged amino acid. It is essential in humans, meaning the body cannot synthesize it: it must be obtained from the diet. Threonine is synthesized from aspartate in bacteria such as E. coli.^[3] It is encoded by all the codons starting AC (ACU, ACC, ACA, and ACG).

Threonine sidechains are often hydrogen bonded; the most common small motifs formed are based on interactions with serine: ST turns, ST motifs (often at the beginning of alpha helices) and ST staples (usually at the middle of alpha helices).

^ Dawson, R.M.C., et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.
^ "Nomenclature and Symbolism for Amino Acids and Peptides". IUPAC-IUB Joint Commission on Biochemical Nomenclature. 1983. Archived from the original on 9 October 2008. Retrieved 5 March 2018.
^ Raïs, Badr; Chassagnole, Christophe; Lettelier, Thierry; Fell, David; Mazat, Jean-Pierre (2001). "Threonine synthesis from aspartate in Escherichia coli cell-free extracts: pathway dynamics". Biochem J. 356 (Pt 2): 425–32. doi:10.1042/bj3560425. PMC 1221853. PMID 11368769.

[1] Dawson, R.M.C., et al., Data for Biochemical Research, Oxford, Clarendon Press, 1959.

[2] "Nomenclature and Symbolism for Amino Acids and Peptides". IUPAC-IUB Joint Commission on Biochemical Nomenclature. 1983. Archived from the original on 9 October 2008. Retrieved 5 March 2018.

[3] Raïs, Badr; Chassagnole, Christophe; Lettelier, Thierry; Fell, David; Mazat, Jean-Pierre (2001). "Threonine synthesis from aspartate in Escherichia coli cell-free extracts: pathway dynamics". Biochem J. 356 (Pt 2): 425–32. doi:10.1042/bj3560425. PMC 1221853. PMID 11368769.

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