A dipeptide is a peptide chain which includes two amino acids. Numerous dipeptides are found in nature, performing a variety of functions, and they can also be made in laboratory environments. Dipeptides have a number of commercial and industrial uses in addition to playing an important role in the biology of many species on Earth. Researchers who work with amino acids are often interested in identifying dipeptides and learning about their function, in addition to researching known dipeptides to learn more about them.
Peptides in general are chains of amino acids. Short chains may be known by terms which indicate the number of amino acids in the grouping, as in the case of dipeptides, while longer chains are known simply as polypeptides, referencing the fact that they contain many amino acids. Long chains of peptides can link to form proteins, more complex structures which include numerous amino acid groupings. Many organisms have the ability to synthesize protein formation with the assistance of enzymes, and enzymes can also be used to break down proteins and peptides into units which can be processed by the body.
During digestion, the digestive tract starts to break down dietary proteins into polypeptides, and these can be broken down into smaller units such as dipeptides. This is done by attacking the peptide bond which links two amino acids together. Once broken down, the substances can be absorbed by the body as needed. At least one dipeptides actually signals the body to produce enzymes which can be used in digestion.
If the body has a need for a particular dipeptide, it can absorb it through the intestinal tract or synthesize it if needed, depending on the dipeptide. Making peptides can use up energy in the body, while breaking them down is much easier. Numerous dipeptides can be found in the body. One example if kyotorphin, found in the brain, where it acts as part of the system used to regulate pain. Other dipeptides do things like reducing fatigue and playing a role as antioxidants.
A famous example of a dipeptide with industrial uses is aspartame, an artificial sweetener. Developed in the 1970s, aspartame was later demonized and held responsible for a wide range of health care problems. Additional study suggested that while this dipeptide could be dangerous for some people in high quantities, the low level use of aspartame as an artificial sweetener was probably not a cause for concern.