Valine is an aliphatic amino acid that is closely related to leucine and isoleucine both in structure and function.  These amino acids are extremely hydrophobic and are almost always found in the interior of proteins.  They are also seldom useful in routine biochemical reactions, but are relegated to the duty of determining the three-dimensional structure of proteins due to their hydrophobic nature.  They are also essential amino acids and must be obtained in the diet or through supplementation.

Branched-chain amino acids are needed for the maintenance of muscle tissue and appear to preserve muscle stores of glycogen – a storage form of carbohydrate that can be converted into energy.

When fed to rats, valine has been shown to give rise to a small but significant amount of liver glycogen. When valine is fed to a rat suffering from a ketosis, the excretion of acetone bodies is markedly decreased.  This is true both in a ketonuria arising from endogenous stores and when the feeding of sodium butyrate increases the already existing acidosis.

Important sources of valine include soy flour, cottage cheese, fish, meats, and vegetables.  Valine is incorporated into proteins and enzymes at the molar rate of 6.9 percent when compared to the other amino acids.

Sources:  Wikipedia, Orthomolecular, The Journal of Biological Chemistry