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Isoleucine is an amino acid that is essential for the diet of humans and animals. It must be obtained from external food sources. This amino acid is important for many biochemical reactions in the body, and errors in metabolism can have drastic consequences. It is also used to treat burn victims, and is taken as a supplement by body builders.
Proteins are comprised of chains of amino acids, which always contain carbon, hydrogen, oxygen, and nitrogen. They have a carboxylate (COOH) group on one end and an amino (NH2) group on the other. The rest of the molecule varies. The isoleucine structure has a side chain comprised of a branch of four carbon atoms with accompanying hydrogen atoms, and does not contain any double bonds. It is called a branched chain amino acid(BCAA), along with the amino acids leucine and valine.
All of these amino acids are essential for humans and animals. They are normally consumed as protein components. Food from animals can provide all of the essential amino acids, but there are a number of others that are also needed to synthesize proteins. Some plant sources provide most of these necessary amino acids, and, if one eats many different plant-based foods, this should lead to a diet that contains all the amino acids that are needed for proper body function.
The World Health Organization (WHO) recommends that an adult with a body weight of 154 lb (70 kg) consume .05 oz (1.4 g) of isoleucine daily. Most people already get enough from their diet, but people who eat a low protein diet or exercise vigorously must sometimes take supplements. If one does take these, one should be sure that it provides a proper balance of leucine and valine. If there are problems with kidney or liver function, a doctor should be consulted before taking these amino acids.
Leucine, valine, and isoleucine make up a significant amount of the human body’s skeletal muscle. Protein synthesis is another function. Isoleucine and valine can also be metabolized during fasting or intense exercise to form glucose, helping to regulate blood sugar levels.
Some people have rare genetic disorders in isoleucine metabolism that can be detected by the presence of breakdown products in the urine. Such illnesses can cause severe problems in the brain, along with other symptoms. One such disorder is known as Maple Syrup Urine Disease, and involves an accumulation of all of the BCAAs and their breakdown products.
All of the BCAAs have side chains that are hydrophobic, meaning they are repelled by water. Because of this tendency, they tend to bury within the interior of molecules. This gives them a significant effect on maintaining the three-dimensional structure of proteins. They can also be involved in the protein’s binding and recognition of hydrophobic compounds, such as lipids.
Isoleucine is present in only one form in proteins, and this is L-isoleucine. The molecule has the capability to exist as different forms that are mirror images of each other. These are referred to as stereoisomers. There are four of them: D- and L-isoleucine, and D- and L-alloisoleucine.