Mice with a genetic taurine deficiency had a nearly complete depletion of skeletal and cardiac muscle taurine levels and a reduction of more than 80% of exercise capacity compared to control mice. Taurine is necessary for normal skeletal muscle functioning. Taurine has been shown to reduce the secretion of apolipoprotein B100 and lipids in HepG2 cells. Role in nutrition and cardiovascular health Taurine reacts with these halogenating agents to form N-chloro- and N-bromotaurine, which are less toxic than their precursors hypohalides. Taurine functions as an antioxidant, suppressing the toxicity of hypochlorite and hypobromite produced physiologically. It is a biosynthetic precursor to the bile salts sodium taurochenodeoxycholate and sodium taurocholate. Taurine is essential for cardiovascular function and development and function of skeletal muscle, the retina, and the central nervous system. It is also found in various dietary supplements aimed towards athletes. Many contain 1000 mg per serving, and some as much as 2000 mg. Taurine is an ingredient in some energy drinks. However, this practice has never been rigorously studied, and as such it has yet to be proven to be necessary, or even beneficial. Taurine is present in breast milk, and has been added to many infant formulas, as a measure of prudence, since the early 1980s. Prematurely born infants are believed to lack the enzymes needed to convert cystathionine to cysteine, and may, therefore, become deficient in taurine. Plasma taurine was 78% of control values, and urinary taurine was 29%. Taurine levels were found to be significantly lower in vegans than in a control group on a standard American diet. The availability of taurine is affected depending on how the food is prepared, raw diets retaining the most taurine, and baking or boiling resulting in the greatest taurine loss. According to a third study, taurine consumption was estimated to vary between 40 and 400 mg/day. In another study, taurine intake was estimated to be generally less than 200 mg/day, even in individuals eating a high-meat diet. The mean daily intake from omnivore diets was determined to be around 58 mg (range from 9 to 372 mg) and to be low or negligible from a strict vegan diet. Taurine occurs naturally in fish and meat. Hypotaurine is then oxidized to taurine as described above. The cystathionine is then converted to hypotaurine by the sequential action of three enzymes: cystathionine gamma-lyase, cysteine dioxygenase, and cysteine sulfinic acid decarboxylase. Taurine is also produced by the transsulfuration pathway, which converts homocysteine into cystathionine. Hypotaurine is enzymatically oxidized to yield taurine by hypotaurine dehydrogenase. Cysteine sulfinic acid, in turn, is decarboxylated by sulfinoalanine decarboxylase to form hypotaurine. In this pathway, cysteine is first oxidized to its sulfinic acid, catalyzed by the enzyme cysteine dioxygenase. Mammalian taurine synthesis occurs in the pancreas via the cysteine sulfinic acid pathway. Taurine is naturally derived from cysteine. In the laboratory taurine can be produced by alkylation of ammonia with bromoethanesulfonate salts. Most of these enterprises employ the ethanolamine method to produce a total annual production of about 3,000 tonnes. As of 2010, China alone has more than 40 manufacturers of taurine. In 1993, about 5,000–6,000 tonnes of taurine were produced for commercial purposes: 50% for pet food and 50% in pharmaceutical applications. A direct approach involves the reaction of aziridine with sulfurous acid.
Synthetic taurine is obtained by the ammonolysis of isethionic acid (2-hydroxyethanesulfonic acid), which in turn is obtained from the reaction of ethylene oxide with aqueous sodium bisulfite. The sulfonic acid has a low p K a ensuring that it is fully ionized to the sulfonate at the pHs found in the intestinal tract.
Taurine exists as a zwitterion H 3N +CH 2CH 2SO − 3, as verified by X-ray crystallography. 5.1 In cosmetics and contact lens solutionsĬhemical and biochemical features.3.1 Role in nutrition and cardiovascular health.2.1 Energy drinks and workout supplements.
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