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Valine

There are around twenty three amino acids which act as the molecular building blocks of proteins. Out of all these amino acids nine are called as indispensable amino acids or essential amino acids, hence they must be supplied from some food or supplement source while others are known as nonessential or are dispensable amino acids or conditionally indispensable and human body is able to synthesize them through biosynthesis process.

The content and balance of both types of amino acids is used to determine the body and health building value of a protein food or supplement. The amount of energy released by protein is also influenced by the presence of other bio molecules like carbohydrates, fats as well as to the amount of the specific amino acids categories. For example; nonessential or are dispensable amino acids like glutamine, leucine and iso-leucine has less importance compare to indispensable amino acids or essential amino acids as they're synthesized too slowly to support maximum growth.
Even if a source has a perfect amino acid profile, it is important that to what extent these acids are actually delivered to the tissues in need which further raises the issues of digestion, absorption and actual bio availability of amino acids in body.

 

Valine Structure

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  • Valine is an aliphatic, hydrophobic, non-polar and an essential amino acid which is usually found in the interior of proteins and named after the plant valerian.
  • It was first discovered by Emil Fischer in 1901.
  • The side chain of valine contains a non polar branched alkyl group, isopropyl group and show quite similarities with threonine in their shape and volume.
  • Valine is found almost in the interior proteins due to its hydrophobic nature and its presence tends to favor the formation of helical structures.
  • It is abbreviated as Val or V with the chemical formula HOOC-CH(NH2)CH(CH3)2 and molecular mass 117.15 g $mol^{-1}$.
  • The genetic codons for valine are GUG, GUC, GUU, and GUA. It is quite soluble in water and gets decomposed over 571 K temperature.
  • The IUPAC name of valine amino acid is 2-amino-3-methylbutanoic acid

Valine Structure
Two possible configurations of optically active Valine amino acid are as follow.
Valine Amino Acid

Since valine consist of a neutral side chain; hence it can show three possible structures in different mediums. In acidic medium, it exists as positive ion and in basic medium as a negative ion. One structure is overall neutral and contains two opposite charges called as zwitterion.

zwitterion

Hence the isoelectric point for valine will be equals to the average of, these two $pK_{a}$'s; pI = 1/2 ($pK_{a1}$ + $pK_{a2}$). The value of $pK_{a}$'s for valine are 2.32 ($pK_{a1}$) and 9.62($pK_{a2}$) and isoelectric point is 5.96.

Oxaloacetate acts as precursor for the synthesis of valine amino acid and this biosynthesis moves parallel to the synthesis of isolucine. This whole process involves four enzymes, Valine aminotransferase, Acetolactate synthase, Dihydroxyacid dehydratase and Acetohydroxy acid isomeroreductase.

Synthesis of Valine Amino Acid

Valine Benefits

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Valine is an essential amino acid, hence must be ingested through foods or supplements. Out of both configurations, L-Valine mainly involves in biochemical processes. It is actively taken by muscles but not processed by liver and effects the brain uptake of neurotransmitter precursors like trptophan and phenylalanine. The main food sources of Valine are Poultry and milk, rice and other cereals, kidney
beans and other legumes, leafy vegetables and pulses, mushrooms, peanuts, soy protein, finger millet, pistachio and cashew nuts, piyal see ds and peaches.

Valine is generally taken as a part of the amino-acid combination with phenylalanine, methionine and tryptophan in the ratio of 3:2:2:1 (phenylalanine-valine-methionine-tryptophan) and results in decreased food intake in 50 per cent of obese women.

The deficiency of valine amino acid causes Maple syrup urine disease (MSUD) in which the urine from patients smells like maple syrup. Its deficiency may affect the myelin covering of the nerves.
Some important benefits of Valine are as follows.
  1. L-Valine involves in improvement of insomnia, nervousness, in disorders of the muscles, mental and emotional upsets and also effective as an appetite suppressant.
  2. L-Valine also regulates the immune system and essential for muscle tissue repair and muscle metabolism as well as increases exercise endurance.
  3. L-Valine required for the proper performance of the nervous system and prevents the nervous and digestive disorders.
  4. Valine amino acid is also used by bodybuilders, in conjunction with other amino acids like isoleucine and leucine to promote muscle growth and as energy source. It helps to repair tissues which are damaged during physical activity. These branched-chain amino acids help the skeletal muscle to withstand metabolic stress and also help to increase endurance and energy.
  5. Valine is also helpful in maintenance of proper amount of nitrogen content in the human body. Because of the presence of a branched side chain in Valine, it can be used as an energy source for muscles and preserving the use of glucose.
  6. Valine involves with other branched-chain amino acid (BCAA) like isoleucine and leucine, to promote normal growth, regulate blood sugar, repair tissues and provide energy. It helps to stimulate the central nervous system for proper mental functioning.
  7. Valine is able to remove potentially toxic excess nitrogen from the liver, and transport nitrogen to other tissues in the body. It can be helpful for the treatment of liver and gallbladder disease and damage to these organs caused by alcoholism and drug abuse. Hence Valine helps in treatment of reverse hepatic encephalopathy, or alcohol-related brain damage. Supplements of L-valine can be used to improve cognitive performance.
  8. Although Valine is an essential amino acid, yet an excessive intake of valine may cause hallucinations and a skin crawling sensation. It can also disrupt kidney function and liver and increase the amount of ammonia in the body.
  9. Valine and other branched-chain amino acids are essential nutrients and used to treat brain conditions due to liver disease like chronic hepatic encephalopathy and latent hepatic encephalopathy, a movement disorder known as tardive dyskinesia, amyotrophic lateral sclerosis (ALS, Lou Gehrig's disease), a disease called spinocerebellar degeneration, a genetic disease called McArdle's disease, cancer patients and poor appetite in elderly kidney failure patients. L valine supplements are used to prevent fatigue and improve concentration. It also helps to improve exercise performance and reduce protein breakdown.

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