Taurine activation

Taurolidine (bis-[l,l-dioxoperhydro-l,2,4-thiadiazinyl-4] methane) is a condensate of two molecules of the amino acid taurine and three molecules of formaldehyde. It is more stable than noxythiolin in solution and has similar uses. The activity oftaurolidine is stated to be greater than that of formaldehyde. 

This area has been covered in a review by Eldefrawi and Eldefrawi [23]. The GABA -receptor channel is activated by GABA (Fig. 2), avermectin, muscimol, taurine (Fig. 2) and j -alanine (Fig. 2). The activation by agonists is potentiated by benzodiazepines and barbiturates. The channel is blocked by the competitive... 

Low levels of hypochlorous acid can function as a mediator in cell activation, induce NFKB heterodimer p50 /p65 in a T-lymphocytic cell line through proteolysis of IKB and pl05 inhibitors. Hypochlorous acid will also contribute to the release of TNFo in cellular supernatants of T-lymphocytes which are capable of commencing activation in non-induced cells (Schoonbroodt et ah, 1997). Hypochlorous acid can react with amines to produce chloroamines and N-chlorinated derivatives that have a long lifetime in plasma. Taurine, a sulfonated amino acid, will finally combine with these two products to reduce their toxicity. 

The desulfinase enzyme was reported to have narrow substrate specificity. In addition to HBPSi, only 2-phenyl benzene sulfinate was reported to serve as a substrate [164], It was found to be inactive against benzene sulfinate, cysteine sulfinate, benzene sulfonate, /7-toluene sulfonate, 1-octane sulfonate, methane sulfonate, and taurine. This enzyme was found to be inhibited by HBP beginning at 0.5 mM with complete loss of activity at 9 mM HBP, but was not affected by sulfite. 

Vohra and Hui [352] showed that the pretreatment of cultured neutrons with taurine suppressed lipid peroxidation and the loss of glutathione peroxidase activity induced in these cells by carbon tetrachloride. 

Hussy, N., Deleuze, C., Desarmenien, M. G. and Moos, F. C. Osmotic regulation of neuronal activity a new role for taurine and glial cells in a hypothalamic neuroendocrine structure. Prog. Neurobiol. 62 113-134, 2000. 

Fig. 2. Active site of taurine dioxygenase (TauD) with 2-oxoglutarate bound to Fe(II) and a taurine substrate (PDB-Code 1GY9) (31).

Fig. 7. (a) Active site of Taurine dioxygenase TauD after activation by the taurine substrate and (b) a benzoylformato model [Fe(bdtbpza)(02CC(0)Ph)] (6). 

Glycine plays an important inhibitory role in the lower brain stem and spinal cord. Little is known about the synthesis of glycine. It activates a Cl- channel, which is antagonized by strychnine. Other endogenous amino acids may activate the glycine channel, such as taurine and j8-alanine. Neuropeptides... 

Parent M, Anderson A, Baker G. 2003. Septal GABA receptor activation prevents glucose-induced increases in hippocampal extracellular glutamate, GABA, and taurine levels. Society for Neuroscience Abstracts, New Orleans, LA. 

Amino acids and some small peptides are absorbed into the enterocytes in the jejnnnm. The transport of amino acids from the lumen into the ceU is an active process, coupled to the transport of Na ions down a concentration gradient. There are at least six carrier systems with different amino acid specificities neutral amino acids (i.e. those with no net charge, e.g. branched-chain amino acids) neutral plus basic amino acids imino acids (proline, hydroxyproline) and glycine basic amino acids (e.g. arginine and lysine) P-amino acids and taurine acidic amino acids (glutamic and aspartic acids). 

Cholic acid and chenodeoxycholic acid, known as the primary bile acids, are quantitatively the most important metabolites of cholesterol. After being biosynthesized, they are mostly activated with coenzyme A and then conjugated with glycine or the non-pro-teinogenic amino acid taurine (see p. 62). The acid amides formed in this way are known as conjugated bile acids or bile salts. They are even more amphipathic than the primary products. 

Before leaving the liver, a large proportion of the bile acids are activated with CoA and then conjugated with the amino acids g/ycine or taurine (2 cf A). In this way, cholic acid gives rise to glycocholic acid and taurocholic acid. The liver bile secreted by the liver becomes denser in the gallbladder as a result of the removal of water (bladder bile 3). 

Saghatelian A, McKinney MK, Bandell M, Patapoutian A, Gravatt BF, A FAAH-Regulated Class ofN-Acyl Taurines That Activates TRP Ion Channels, Biochemistry 45 9007—9015, 2006. 

Militante JD, Lombardini JB (1999) Taurine uptake activity in the rat retina protein kinase C-independent inhibition by chelerythrine. Brain Res 818 368-374... 

Tallon, M. J., Harris, R. C., Maffulli, N., and Tarnopolsky, M. A. (2007). Carnosine, taurine and enzyme activities of human skeletal muscle fibres from elderly subjects with osteoarthritis and young moderately active subjects. Biogerontology 8,129-137. 

Taurine (2-aminoethanesulfonic acid 4.235) is an inhibitory neurochemical that probably acts primarily as a neuromodulator rather than a neurotransmitter. It is formed from cysteine, and its accumulation can be prevented by the cardiac glycoside ouabain. Although receptor sites and specific actions cannot be elucidated without an antagonist, taurine has been implicated in epilepsy and, potentially, in heart disease. There are a large number of physiological effects attributed to taurine, among them cardiovascular (antiarrythmic), central (anticonvulsant, excitability modulation), muscle (membrane stabilizer), and reproductive (sperm motility factor) activity. Analogs of taurine, phthalimino-taurinamide (4.236) and its iV-alkyl derivatives, are less polar than taurine and are potent anticonvulsant molecules. 

Bile salts secreted into the intestine are efficiently reabsorbed (greater than 95 percent) and reused. The mixture of primary and secondary bile acids and bile salts is absorbed primarily in the ileum. They are actively transported from the intestinal mucosal cells into the portal blood, and are efficiently removed by the liver parenchymal cells. [Note Bile acids are hydrophobic and require a carrier in the portal blood. Albumin carries them in a noncovalent complex, just as it transports fatty acids in blood (see p. 179).] The liver converts both primary and secondary bile acids into bile salts by conjugation with glycine or taurine, and secretes them into the bile. The continuous process of secretion of bile salts into the bile, their passage through the duodenum where some are converted to bile acids, and their subsequent return to the liver as a mixture of bile acids and salts is termed the enterohepatic circulation (see Figure 18.11). Between 15 and 30 g of bile salts are secreted from the liver into the duodenum each day, yet only about 0.5 g is lost daily in the feces. Approximately 0.5 g per day is synthesized from cholesterol in the liver to replace the lost bile acids. Bile acid sequestrants, such as cholestyramine,2 bind bile acids in the gut, prevent their reabsorption, and so promote their excretion. They are used in the treatment of hypercholesterolemia because the removal of bile acids relieves the inhibition on bile acid synthesis in the liver, thereby diverting additional cholesterol into that pathway. [Note Dietary fiber also binds bile acids and increases their excretion.]... 

Studies by Hall et al (1979) have shown that the bile-activated enzyme can be stimulated fifty-fold by freezing and thawing, by Bonification, or by addition of bile salt addition of glycine conjugate was four times more effective than addition of taurine conjugate. Studies on the kinetic and chemical characterization of the enzyme were performed by Wang (1981). 

Melemeleones A and B (320 and 321) possess a 4,9-friedodrimane sesquiterpene array linked to a quinone bearing a taurine and they are structurally related to avarol. Compounds 320 and 321 were isolated from the sponge Dysidea sp. and identified by analysis of their spectroscopic data. Compound 321 showed a moderate inhibitory activity against the pp60v src protein Tyrosine Kinase with an IC50 of 28 pM [236]. 

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