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|Section2= |Section3= }} Thiamine pyrophosphate (TPP or ThPP), or thiamine diphosphate (ThDP), or cocarboxylase〔〕 is a thiamine (vitamin B1) derivative which is produced by the enzyme thiamine diphosphokinase. Thiamine pyrophosphate is a cofactor that is present in all living systems, in which it catalyzes several biochemical reactions. It was first discovered as an essential nutrient (vitamin) in humans through its link with the peripheral nervous system disease Beriberi, which results from a deficiency of thiamine in the diet. TPP works as a coenzyme in many enzymatic reactions, such as: * Pyruvate dehydrogenase complex * Pyruvate decarboxylase in ethanol fermentation * Alpha-ketoglutarate dehydrogenase complex * Branched-chain amino acid dehydrogenase complex * 2-hydroxyphytanoyl-CoA lyase * Transketolase ==Chemistry== Chemically, TPP consists of a pyrimidine ring which is connected to a thiazole ring, which is in turn connected to a pyrophosphate (diphosphate) functional group. The part of TPP molecule that is most commonly involved in reactions is the thiazole ring, which contains nitrogen and sulfur. Thus, the thiazole ring is the "reagent portion" of the molecule. The C2 of this ring is capable of acting as an acid by donating its proton and forming a carbanion. Normally, reactions that form carbanions are highly unfavorable, but the positive charge on the tetravalent nitrogen just adjacent to the carbanion stabilizes the negative charge, making the reaction more favorable. (A compound with positive and negative charges on adjacent atoms is called an ylid or ylide, so sometimes the carbanion form of TPP is referred to as the "ylid form".〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thiamine pyrophosphate」の詳細全文を読む スポンサード リンク
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