Valine

Valine

Names
IUPAC name Valine
Other names 2-amino-3-methylbutanoic acid
Identifiers
CAS Number	516-06-3 Y 72-18-4 (L-isomer) Y 640-68-6 (D-isomer) Y
ChEBI	CHEBI:57762 Y
ChEMBL	ChEMBL43068 Y
ChemSpider	6050 Y
DrugBank	DB00161 Y
EC Number	208-220-0
IUPHAR/BPS	4794
Jmol 3D model	Interactive image
KEGG	D00039 Y
PubChem	1182
UNII	4CA13A832H Y
InChI InChI=1S/C5H11NO2/c1-3(2)4(6)5(7)8/h3-4H,6H2,1-2H3,(H,7,8)/t4-/m0/s1 Y Key: KZSNJWFQEVHDMF-BYPYZUCNSA-N Y InChI=1/C5H11NO2/c1-3(2)4(6)5(7)8/h3-4H,6H2,1-2H3,(H,7,8)/t4-/m0/s1 Key: KZSNJWFQEVHDMF-BYPYZUCNBW
SMILES CC(C)[C@@H](C(=O)O)N
Properties
Chemical formula	C5H11NO2
Molar mass	117.15 g·mol−1
Density	1.316 g/cm3
Melting point	298 °C (568 °F; 571 K) (decomposition)
Solubility in water	soluble
Acidity (pKa)	2.32 (carboxyl), 9.62 (amino)
Vapor pressure	{{{value}}}
Supplementary data page
Structure and properties	Refractive index (n), Dielectric constant (εr), etc.
Thermodynamic data	Phase behaviour solid–liquid–gas
Spectral data	UV, IR, NMR, MS
Y verify (what is YN ?)
Infobox references

Valine (abbreviated as Val or V)^[1] encoded by the codons GUU, GUC, GUA, and GUG is an ɑ-amino acid that is used in the biosynthesis of proteins. It contains an α-amino group (which is in the protonated -+NH3 form under biological conditions), an α-carboxylic acid group (which is in the deprotonated –COO- form under biological conditions), and a side chain isopropyl variable group, classifying it as a non-polar amino acid. It is essential in humans, meaning the body cannot synthesize it and thus it must be obtained from the diet. Human dietary sources are any proteinaceous foods such as meats, dairy products, soy products, beans and legumes.

Along with leucine and isoleucine, valine is a branched-chain amino acid. In sickle-cell disease, valine substitutes for the hydrophilic amino acid glutamic acid in β-globin. Because valine is hydrophobic, the hemoglobin is prone to abnormal aggregation.

History and etymology

Valine was first isolated from casein in 1901 by Emil Fischer. The name valine comes from valeric acid, which in turn is named after the plant valerian due to the presence of the acid in the roots of the plant.

Nomenclature

According to IUPAC, carbon atoms forming valine are numbered sequentially starting from 1 denoting the carboxyl carbon, whereas 4 and 4' denote the two terminal methyl carbons.

Biosynthesis

Valine is an essential amino acid, hence it must be ingested, usually as a component of proteins. It is synthesized in plants via several steps starting from pyruvic acid. The initial part of the pathway also leads to leucine. The intermediate α-ketoisovalerate undergoes reductive amination with glutamate. Enzymes involved in this biosynthesis include:

1. Acetolactate synthase (also known as acetohydroxy acid synthase)
2. Acetohydroxy acid isomeroreductase
3. Dihydroxyacid dehydratase
4. Valine aminotransferase

Synthesis

Racemic valine can be synthesized by bromination of isovaleric acid followed by amination of the α-bromo derivative

HO₂CCH₂CH(CH₃)₂ + Br₂ → HO₂CCHBrCH(CH₃)₂ + HBr

HO₂CCHBrCH(CH₃)₂ + 2 NH₃ → HO₂CCH(NH₂)CH(CH₃)₂ + NH₄Br

See also

• Valinol

External links

• Valine MS Spectrum
• Isoleucine and valine biosynthesis
• Valine's relationship to prions