Taurine

Taurine (Latin taurus = bull, as it was first isolated from ox (Bos taurus) bile in 1827 by German scientists Friedrich Tiedemann and Leopold Gmelin) or 2-aminoethanesulfonic acid is an acidic chemical substance found in high abundance in the tissues of many animals (metazoa), especially sea animals. Taurine is also found in plants, fungi, and some bacterial species, but in far less abundance. Taurine is a derivative of the sulphur-containing(sulfhydryl) amino acid, cysteine. Although it is often called an amino acid, even in scientific literature, it lacks a carboxyl group and therefore does not qualify as an amino acid. It does contain a sulfonate group and may be called an amino sulfonic acid. Small polypeptides have been identified which contain taurine but to date no tRNA synthetase has been identified as specifically recognizing taurine and capable of charging it to a tRNA.

Biosynthesis

The major pathway for mammalian taurine synthesis occurs in the liver via the cysteine sulfinic acid pathway. In this pathway, the sulfhydryl group of cysteine is first oxidized to cysteine sulfinic acid by the enzyme cysteine dioxygenase. Cysteine sulfinic acid, in turn, is decarboxylated by cysteine sulfinic acid decarboxylase to form hypotaurine. It is unclear whether hypotaurine is then spontaneously or enzymatically oxidized to yield taurine.

Physiological roles

Taurine is conjugated via its amino terminal group with the bile acids chenodeoxycholic acid and cholic acid to form the bile salts sodium taurochenodeoxycholate and sodium taurocholate (see bile). The low pKa (1.5) of taurine's sulfonic acid group ensures that this moiety is negatively charged in the pH ranges normally found in the intestinal tract and thus improves the surfactant properties of the cholic acid conjugate.

Taurine has also been implicated in a wide array of other physiological phenomena including inhibitory neurotransmission, long-term potentiation in the striatum/hippocampus, membrane stabilization, feedback inhibition of neutrophil/macrophage respiratory bursts, adipose tissue regulation, and calcium homeostasis. The evidence for these claims, when compared against that reported for taurine's role in bile acid synthesis and osmoregulation, is relatively poor.

Prematurely-born infants who lack the enzymes needed to convert cystathionine to cysteine may become deficient in taurine. Thus, taurine is a dietary essential nutrient in these individuals and is often added to many infant formulas as a measure of prudence. There is also evidence that taurine in adult humans reduces blood pressure.

Many therapeutic applications of taurine have been investigated. Some conditions that taurine might be useful in treating include: cardiovascular diseases, hypercholesterolemia, epilepsy and other seizure disorders, macular degeneration, Alzheimer's disease, hepatic disorders, alcoholism, and cystic fibrosis. Recent studies show that taurine supplements taken by mice on a high-fat diet reduced their overall weight. Studies have yet to be done on the effect of taurine on obesity in humans.

Taurine and animals

Taurine is essential for cat health, as they cannot synthesize the compound. The absence of taurine causes the cat's retina to slowly degenerate, causing eye problems and (eventually) irreversible blindness. This condition is called central retinal degeneration (CRD). In addition, taurine deficiency can cause feline dilated cardiomyopathy, and supplementation can reverse left ventricular systolic dysfunction. (Pion et al 1988)

Taurine levels in vegans

Taurine levels were found to be significantly lower in vegans (staff members of a Seventh Day Adventist college) than in a control group on a standard American diet. Plasma taurine was 78% of control values, and urinary taurine only 29%.

Commercial uses for taurine


In recent years, taurine has become a common ingredient in energy drinks. Taurine is also often used in combination with bodybuilding supplements such as creatine and anabolic steroids, but there is no evidence to suggest that it has any positive effect on muscle growth.

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