Valine

Valine
IUPAC name
Valine
Other names
2-amino-3-methylbutanoic acid
Identifiers
CAS number 516-06-3 YesY, 
72-18-4 (L-isomer)
640-68-6 (D-isomer)
PubChem 1182
EC-number 208-220-0
Properties[1]
Molecular formula C5H11NO2
Molar mass 117.15 g mol−1
Density 1.316 g/cm3
Melting point

298 ºC decomp.
Solubility in water soluble
 YesY (what is this?)  (verify)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Valine (abbreviated as Val or V)[2] is an α-amino acid with the chemical formula HO2CCH(NH2)CH(CH3)2. L-Valine is one of 20 proteinogenic amino acids. Its codons are GUU, GUC, GUA, and GUG. This essential amino acid is classified as nonpolar. Human dietary sources include cottage cheese, fish, poultry, peanuts, sesame seeds, and lentils.

Along with leucine and isoleucine, valine is a branched-chain amino acid. It is named after the plant valerian. In sickle-cell disease, valine substitutes for the hydrophilic amino acid glutamic acid in hemoglobin. Because valine is hydrophobic, the hemoglobin does not fold correctly.

Contents

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-ketovalerate undergoes reductive amination with glutamate. Enzymes involved in this biosynthesis include:[3]

  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[4]

HO2CCH2CH(CH3)2 + Br2 → HO2CCHBrCH(CH3)2 + HBr
HO2CCHBrCH(CH3)2 + 2 NH3 → HO2CCH(NH2)CH(CH3)2 + NH4Br

References

  1. ↑ Weast, Robert C., ed. (1981), CRC Handbook of Chemistry and Physics (62nd ed.), Boca Raton, FL: CRC Press, p. C-569, ISBN 0-8493-0462-8 .
  2. ↑ "Nomenclature and symbolism for amino acids and peptides (IUPAC-IUB Recommendations 1983)", Pure Appl. Chem. 56 (5): 595–624, 1984, doi:10.1351/pac198456050595 .
  3. ↑ Lehninger, Albert L.; Nelson, David L.; Cox, Michael M. (2000), Principles of Biochemistry (3rd ed.), New York: W. H. Freeman, ISBN 1-57259-153-6 .
  4. ↑ Marvel, C. S. (1940), "dl-Valine", Org. Synth. 20: 106, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV3P0848 ; Coll. Vol. 3: 848 .

External links

The 20 Common Amino Acids ("dp" = data page)
Branched-chain amino acids
Isoleucine · Leucine · Valine
Non Branch-chain
Other classifications
Essential amino acids · Ketogenic amino acid · Glucogenic amino acid
By properties
Aliphatic
Valine  · Isoleucine  · Leucine  · Methionine  · Alanine  · Proline  · Glycine
Aromatic
Polar, uncharged
Positive charge (pKa)
Lysine (≈10.8)  · Arginine (≈12.5)  · Histidine (≈6.1)
Negative charge (pKa)
Aspartic acid (≈3.9)  · Glutamic acid (≈4.1)  · Cysteine (≈8.3)  · Tyrosine (≈10.1)
General
biochemical families: prot · nucl · carb (alco, glys, glpr) · lipd (fata, phld, strd, gllp, eico, ttpy) · amac · ncbs
Amino acid metabolism metabolic intermediates
K→acetyl-CoA
Saccharopine · Allysine · α-Aminoadipic acid · α-Aminoadipate · Glutaryl-CoA · Glutaconyl-CoA · Crotonyl-CoA · β-Hydroxybutyryl-CoA
α-Ketoisocaproic acid · Isovaleryl-CoA · 3-Methylcrotonyl-CoA · 3-Methylglutaconyl-CoA · HMG-CoA
N'-Formylkynurenine · Kynurenine · Anthranilic acid · 3-Hydroxykynurenine · 3-Hydroxyanthranilic acid · 2-Amino-3-carboxymuconic semialdehyde · 2-Aminomuconic semialdehyde · 2-Aminomuconic acid · Glutaryl-CoA
G
G→pyruvate→citrate

3-Phosphoglyceric acid

glycine→creatine: Glycocyamine · Phosphocreatine · Creatinine
G→glutamate→
α-ketoglutarate
Urocanic acid · Imidazol-4-one-5-propionic acid · Formiminoglutamic acid · Glutamate-1-semialdehyde
1-Pyrroline-5-carboxylic acid
Ornithine · Putrescine · Agmatine
other
cysteine+glutamate→glutathione: γ-Glutamylcysteine
G→propionyl-CoA→
succinyl-CoA
valine→
α-Ketoisovaleric acid · Isobutyryl-CoA · Methacrylyl-CoA · 3-Hydroxyisobutyryl-CoA · 3-Hydroxyisobutyric acid · 2-Methyl-3-oxopropanoic acid
2,3-Dihydroxy-3-methylpentanoic acid · 2-Methylbutyryl-CoA · Tiglyl-CoA · 2-Methylacetoacetyl-CoA

generation of homocysteine: S-Adenosyl methionine · S-Adenosyl-L-homocysteine · Homocysteine

conversion to cysteine: Cystathionine · alpha-Ketobutyric acid+Cysteine
α-Ketobutyric acid
propionyl-CoA→
Methylmalonyl-CoA
4-Hydroxyphenylpyruvic acid · Homogentisic acid · 4-Maleylacetoacetate
G→oxaloacetate
see urea cycle
Other
Cysteine metabolism
Cysteine sulfinic acid

: MET

mt, r//c/p/i/y, f/s/l/o, a/u, n, h

rgcp//y, f/s/l/o, au, n, h,

m(A16, C10),i(//c//i/y, /s/o, a/u,n, h)
Stub icon This biochemistry article is a stub. You can help Wikipedia by expanding it.