Taurine, or 2-aminoethanesulfonic acid, is an amino sulfonic acid, but it is often referred to as an amino acid, a chemical that is a required building block of protein. Taurine is found in large amounts in the brain, retina, heart, and blood cells called platelets. Taurine has many biological roles, such as conjugation of bile acids, antioxidation, osmoregulation, membrane stabilization, and modulation of calcium signaling. It is essential for cardiovascular function, and development and function of skeletal muscle, the retina, and the central nervous system. Taurine is an ESSENTIAL amino acid for cats. (Read More: The Journal of Nutrition, Volume 108, Issue 5, May 1978 and Wikipedia).