Valine

3D model of Valine

Valine is an alpha-amino acid that is used in the biosynthesis of proteins. It contains an amino group, a carboxyl group, and a side chain isopropyl group, classifying it as a non-polar, aliphatic amino acid. Valine is one of the branched-chain amino acids (BCAAs), along with leucine and isoleucine.

Structure

Valine is encoded by the codons GUU, GUC, GUA, and GUG. Its chemical formula is C₅H₁₁NO₂, and it has a molar mass of 117.15 g/mol. The side chain of valine is a simple isopropyl group, making it hydrophobic and thus often found in the interior of proteins.

Function

Valine is essential for muscle growth, tissue repair, and the maintenance of proper nitrogen balance in the body. As a BCAA, it is metabolized in the muscle rather than the liver, which makes it particularly important for athletes and individuals with muscle-wasting diseases.

Dietary Sources

Valine is an essential amino acid, meaning it must be obtained through the diet. Rich sources of valine include meat, dairy products, soy products, beans, and legumes.

Metabolism

Valine is metabolized in the body through a series of enzymatic reactions. It is first transaminated to form alpha-ketoisovalerate, which is then converted to isobutyryl-CoA. This compound undergoes further reactions to eventually form succinyl-CoA, which enters the citric acid cycle.

Clinical Significance

Valine levels can be affected in certain metabolic disorders, such as maple syrup urine disease, where there is a deficiency in the enzyme complex responsible for breaking down BCAAs. Symptoms of valine deficiency include fatigue, muscle weakness, and impaired cognitive function.

Related Pages

• Amino acid
• Branched-chain amino acid
• Protein synthesis
• Essential amino acid