Thiamin triphosphate TTP

Thiamine uptaken into the cell is phosphorylated to TDP by the enzyme thiamine pyrophosphokinase. TDP is then further phosphorylated to thiamine triphosphate (TTP) or is dephosphorylated to thiamine monophosphate (TMP). 

This vitamin, also called aneurin, is the antiberiberi factor. The active coenzyme form is thiamine pyrophosphate (TPP), or coearboxylase. Thiamine triphosphate (TTP) may be an active form in the central nervous system. Of the thiamine in the body, 10% occurs as TTP, 80% as TPP, and 10% as TMP (thiamine monophosphate) (Figure 38-12). 

Description. Thiamin is a water-soluble B-complex vitamin, previously known as vitamin B, or aneurine. " Isolated and characterized in the 1930s, thiamin was one of the first organic compounds to be recognized as a vitamin. " Thiamin occurs in the human body as free thiamin and its phosphorylated forms thiamin monophosphate (TMP), thiamin triphosphate (TTP), and thiamin pyrophosphate (TPP). 

Chemical structure (Figure 6). Pyrimidine and thiazole moiety linked by methylene bridge - phos-phorylated forms thiamine monophosphate (TMP), thiamine diphosphate (TDP), thiamine triphosphate (TTP). 

TMP), thiamine diphosphate (TDP also known as thiamine pyrophosphate, TPP), and thiamine triphosphate (TTP). TDP, the best characterized form, in its role as a eoenzyme for molecules involved in carbohydrate metabolism e.g. transketolase and pyruvate dehydrogenase) is important for energy production and numerous metabolic functions (Lonsdale 2006). 

Thiamine is a relatively simple compound consisting of a pyrimidine and a thiazole ring. It exists naturally in most types of foods as free thiamine and phosphorylated forms including thiamine monophosphate (TMP), thiamine diphosphate or pyrophosphate (TPP), and thiamine triphosphate (TTP) (Tanphaichitr 2001) (Figure 17.1). Although all forms exist in animal and plant foods, thiamine as the free (non-phosphorylated) form is mainly found in plant-based foods whereas, in animal products, 80% of thiamine is represented by TPP and lesser amounts by TMP and triphosphate TTP. 

The structures of the phosphate esters of thiamine are also shown in Figure 1. Thiamine monophosphate (TMP), thiamine pyrophosphate (TPP), and thiamine triphosphate (TTP) are commonly found in organisms. About 80% to 90% of the total thiamine content in cells is TPP, the coenzyme form of thiamine. In some animal tissues, especially pig skeletal muscle (2) and chicken white skeletal muscle (3), TTP is present in an extremely high amount (70% to 80% of total thiamine—i.e., thiamine plus thiamine phosphate esters). However, TTP has no coenzyme activity. Thiamine pyrophosphate in the dried state is stable for several months when stored at a low temperature in the dark. In solution, TPP is unstable and partially decomposes to TMP and/or thiamine when stored for several months at pH 5 and 38°C. However, TPP in solution at pH 2 to 6 and at 0°C is... 

Further phosphates of thiamine, thiamine monophosphate (TMP), and thiamine triphosphate (TTP) have also been found as natural products 19, 80). Kiessling has shown that potato apyrase, ch cleaves Y-phosphates, hydrolyzes TTP in the same manner as it does ATP, suggesting that the two compounds have their phosphate groups arranged in a similar manner 81). Yeast incorporates P K)4 to a greater extent into the phosphate of TTP than into any other thiamine phosphate 88). Neither TMP nor TTP possess cocarboxylase activity 83). TTP can, however, transfer its terminal phosphate enzymically to glucose, just as does ATP 84). 

Fig. 2 Intercellular trafficking and thiamine and thiamine esters in brain. TMP thiamine monophosphate, TDP thiamine diphosphate, TTP thiamine triphosphate, TPKinase thiamine pyrophosphokinase...

Elecfiical stimulation of a wide range of nerve preparations results in thiamine release suggesting a role for the vitamin in membrane function that is independent of its enzyme cofactor role mediated by TDP. TDP is further phosphorylated to thiamine triphosphate (Fig. 2). Although its precise role has yet to be elucidated, it has been proposed that TTP activates high-conductance chloride channels (Bettendorf,... 

Thiamine is required by the body as the pyrophosphate (TPP) in two general types of reaction, the oxidative decarboxylation of a keto acids catalyzed by dehydrogenase complexes and the formation of a-ketols (ketoses) as catalyzed by transketolase, and as the triphosphate (TTP) within the nervous system. TPP functions as the Mg -coordinated coenzyme for so-called active aldehyde transfers in mul-tienzyme dehydrogenase complexes that affect decarboxyia-tive conversion of a-keto (2 oxo) acids to acyl-coenzyme A (acyl-CoA) derivatives, such as pyruvate dehydrogenase and a-ketoglutarate dehydrogenase. These are often localized in the mitochondria, where efficient use in the Krebs tricarboxylic acid (citric acid) cycle follows. 

C,2H,8C1N404PS M 380.791 Vitamin B deriv. used clinically. Mp ca. 200°. O-Triphosphate Thiamine triphosphate. Thiamine triphosphoric acid. TTP Isol. from animal tissues. Cryst. (EtOH aq.). 

TPP thiamine pyrophosphate Trp tryptophan TTP thymidine triphosphate Tyr tyrosine U uracil... 

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