It’s commonly believed that taurine is an amino acid. There are a few reasons for the misconception. The chemical name for taurine is 2-aminoethanesulfonic acid, so it has an amino group and is an acid. Taurine has the “-ine” ending that is common with other amino acids, plus it is a nutritional supplement. However, the molecule does not have the amino acid structure. Taurine has a sulfonic acid group rather than the carboxyl group found in amino acids.
Taurine is an important molecule in people and animals. It accounts for about 0.1% of total human body weight. It is a major component of bile and is used to moderate calcium signaling, osmoregulation, and proper muscle function. Human can synthesize taurine from the amino acid cysteine. However, cats and other carnivores cannot, so they have to obtain it from their diet. Taurine is important for development of other animals, too. Some birds seek out taurine-rich spiders to feed to their young.