Valine

Valine is an amino acid obtained by hydrolysis of proteins and was first isolated by the German chemist Emil Fischer in 1901 from casein and is not only an essential amino acid but is also a branched-chain amino acid (the others are isoleucine and leucine) found in high concentration in the muscles.

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 is prone to abnormal aggregation.
 * Valine ** (abbreviated as ** Val ** or ** V ** ) [|[3]] 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.

It has a stimulating effect and is needed for muscle metabolism, repair and growth of tissue and maintaining the nitrogen balance in the body. Since it is a branched-chain amino acid, it can be used as an energy source in the muscles, and in doing so preserves the use of glucose. Many amino acids become deficient with drug addiction, and here it also plays an important role and there are indications that it may also be beneficial in treating or reversing hepatic encephalopathy, or alcohol related brain damage, as well as degenerative neurological conditions.

Maple syrup urine disease (MSUD) is caused by the inability to metabolize leucine, isoleucine, and valine. The disease is so named because urine from affected people smells like maple syrup. A deficiency may affect the myelin covering of the nerves.

Very high levels of valine can cause symptoms such as a crawling sensation on the skin, as well as hallucinations. Individuals with kidney or liver disease should be careful in consuming high intakes of amino acids without consulting their doctor.

Valine is often used by bodybuilders, (in conjunction with leucine and isoleucine), to promote muscle growth, tissue repair and energizer, although little scientific evidence supports these claims. Studies have however shown that these three substances might be useful in restoring muscle mass in people with liver disease, injuries, or who have undergone surgery.

Melting point: 298 degrees C Ingested as a component of proteins

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: [|[4]] 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
 * 1) [|Acetolactate synthase] (also known as acetohydroxy acid synthase)
 * 2) [|Acetohydroxy acid isomeroreductase]
 * 3) [|Dihydroxyacid dehydratase]
 * 4) [|Valine aminotransferase]


 * [|Molecular formula] || C 5 H 11 NO 2 ||
 * [|Molar mass] || 117.15 g mol −1 ||
 * [|Density] || 1.316 g/cm 3 ||
 * [|Melting point] || 298 °C decomp. ||
 * [|Solubility] in [|water] || soluble ||
 * [|Acidity] (p//K// a ) || 2.32 (carboxyl), 9.62 (amino)[|[1]] ||