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Taurine

Taurine (2-aminoethanesulfonic acid) is the amino acid with the highest concentration in the human body. It is derived from methionine and cysteine and is not utilized in protein synthesis but found free or in some simple peptides. Taurine is a unique amino acid, which lacks a carboxyl group, and as such it does not enter into protein synthesis. Taurine is a sulfonic amino acid which is biologically synthesized in the body of mammals. This exists in a state free from intracellular fluids, and is found in skeletal muscles, such as cerebrum, eyeball, muscles, liver and the like, free amino acid groups and at high concentrations. Taurine is considered to be a metabolic factor involved in the conjugation and excretion of bile acids. Taurine is also a free amino acid present in most cells of the body including the adrenal glands, blood, cardiac muscle and brain. Taurine is a major constituent of the free amino acid pool in mammalian neural tissue, where it functions as a neurotransmitter or neuromodulator in the central nervous system. Taurine is considered to be important for the maintenance of the intracellular ion, in particular calcium, homeostasis. Taurine appears to do this by affecting several membrane systems. It modulates calcium and sodium channels through the cellular calcium/sodium-exchanger and a taurine/sodium-exchanger. Furthermore, taurine can act as an antioxidant and may react with a variety of potentially toxic intracellular aldehydes, including malonic dialdehyde. Taurine is structurally related to the inhibitory amino acid gamma-aminobutyric acid (GABA) and exerts inhibitory effects on the brain, suggesting a role as a neurotransmitter or neuromodulator. Taurine can be released from both neurons and glial cells by receptor-mediated mechanisms as well as in response to cell volume changes. Taurine appears to be an important amino acid for the modulation of cellular calcium levels, exhibiting a remarkable biphasic action by increasing or decreasing calcium levels appropriate to the maintenance of cellular calcium homeostasis. In the heart, taurine appears to do this by affecting several myocardial membrane systems. Taurine displays inhibitory neurotransmitter properties over sensitive pathways in the brain stem and spinal cord. Taurine is a known neuromodulator and is an inhibitory amino acid. Another key function is as an osmolyte in most cells. Taurine may regulate many biological processes, including heart rhythm, contractile function, blood pressure, platelet aggregation, neuronal excitability, body temperature, learning, motor behavior, food consumption, eye sight, sperm motility, cell proliferation and viability, energy metabolism and bile acid synthesis. Taurine deficiency in the feline diet has been shown to be associated with the incidence of dilated cardiomyopathy, a condition in which the heart enlarges and becomes globular from the dilatation of the ventricles and the atria. Supplementing the diet of cats with taurine has proven effective in reducing the incidence of cardiomyopathy and as an anticonvulsant. Taurine has been used long in foods and drinks as a health additive having various functional characteristics, such as improvement of the liver function through detoxication and antioxidation actions, decreased blood cholesterol, and blood pressure adjustment. Because of such biological activities, taurine is used as an additive in various health foods or medical supplies, such as weaning diets for babies, gums, drinks, and nutritious tonic drinks, but is not practically used as drugs. Also, its reported therapeutic use was only for therapy of heart diseases.

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