View source for Thiamine pyrophosphate/ja

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{{chembox
| Watchedfields  = changed
| verifiedrevid  = 470606241
| Name           = 
| ImageFile      = Thiamine diphosphate.png
| ImageSize      = 200px
| IUPACName      = 2-[3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl]ethyl phosphono hydrogen phosphate
| OtherNames     = Thiamine diphosphate
| SystematicName = 
| Section1       = {{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 10670483
| ChEBI = 9532
| KEGG = C00068
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = Q57971654Y
| InChI = 1/C12H17N4OS.ClH.H4O7P2/c1-8-11(3-4-17)18-7-16(8)6-10-5-14-9(2)15-12(10)13;;1-8(2,3)7-9(4,5)6/h5,7,17H,3-4,6H2,1-2H3,(H2,13,14,15);1H;(H2,1,2,3)(H2,4,5,6)/q+1;;/p-1
| InChIKey = NBSUTVXQOGUTJX-REWHXWOFAB
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/C12H17N4OS.ClH.H4O7P2/c1-8-11(3-4-17)18-7-16(8)6-10-5-14-9(2)15-12(10)13;;1-8(2,3)7-9(4,5)6/h5,7,17H,3-4,6H2,1-2H3,(H2,13,14,15);1H;(H2,1,2,3)(H2,4,5,6)/q+1;;/p-1
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = NBSUTVXQOGUTJX-UHFFFAOYSA-M
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 136-08-3
| PubChem = 1132
| SMILES = Cc2ncc(C[n+]1csc(CCOP(=O)(O)OP(=O)(O)O)c1C)c(N)n2
| MeSHName = Thiamine+pyrophosphate
  }}
| Section2       = {{Chembox Properties
| Formula = C<sub>12</sub>H<sub>19</sub>N<sub>4</sub>O<sub>7</sub>P<sub>2</sub>S<sup>+</sup>
| MolarMass = 425.314382  g/mol
| Appearance = 
| Density = 
| MeltingPt = 
| BoilingPt = 
  }}
| Section3       = {{Chembox Hazards
| MainHazards = 
| FlashPt = 
| AutoignitionPt = 
  }}
| Section4       = 
| Section5       = 
| Section6       = 
}}
'''チアミンピロリン酸'''（'''TPP'''または'''ThPP'''）、または'''チアミン二リン酸'''（'''ThDP'''）、または'''コカルボキシラーゼ'''は、[[enzyme/ja|酵素]]によって生成される[[thiamin/ja|チアミン]]（ビタミンB<sub>1</sub>）の[[derivative (chemistry)/ja|誘導体]]である。[チアミンジホスホキナーゼ]]によって生成される。チアミン・ピロリン酸は[[cofactor (biochemistry)/ja|補因子]]であり、すべての生体系に存在し、いくつかの[[Biochemistry/ja|生化学]]反応を触媒する。
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チアミンピロリン酸は[[cytosol/ja|細胞質]]で合成され、細胞質ではトランスケトラーゼの活性に、ミトコンドリアではピルビン酸、オキソグルタル酸、分岐鎖ケト酸デヒドロゲナーゼの活性に必要である。現在までに、ThPPとThMPのミトコンドリア輸送を担うものとして、酵母ThPPキャリアー（Tpc1p）、ヒトTpc、''[[Drosophila melanogaster/ja|ショウジョウバエ]]''が同定されている。ThPPは、[[diet (nutrition)/ja|食事療法]]におけるチアミンの欠乏に起因する[[peripheral nervous system/ja|末梢神経系]]の[[disease/ja|病気]][[beriberi/ja|脚気]]との関連性から、ヒトの[[essential nutrient/ja|必須栄養素]]（[[vitamin/ja|ビタミン]]）として初めて発見された。

TPPは多くの酵素反応において[[coenzyme/ja|補酵素]]として働く：

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* [[Pyruvate dehydrogenase]] complex
* [[Pyruvate decarboxylase]] in [[ethanol fermentation]]
* [[Alpha-ketoglutarate dehydrogenase]] complex
* [[Branched-chain amino acid dehydrogenase]] complex
* [[2-hydroxyphytanoyl-CoA lyase]] 
* [[Transketolase]]
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==Chemistry==
[[Image:TPP-ylide.svg|thumb|right|The "ylide form" of TPP.]]
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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]].
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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 much more favorable. A compound with positive and negative charges on adjacent atoms is called an [[ylide]], so sometimes the carbanion form of TPP is referred to as the "ylide form".
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==Reaction mechanisms==
In several reactions, including that of pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, and transketolase, TPP catalyses the reversible decarboxylation reaction (aka cleavage of a substrate compound at a carbon-carbon bond connecting a [[carbonyl group]] to an adjacent reactive group—usually a [[carboxylic acid]] or an [[Alcohol (chemistry)|alcohol]]). It achieves this in four basic steps:
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#The carbanion of the TPP ylid [[nucleophilic attack|nucleophilically attacks]] the carbonyl group on the substrate.  (This forms a single bond between the TPP and the substrate.)
#The target bond on the substrate is broken, and its electrons are pushed towards the TPP.  This creates a double bond between the substrate carbon and the TPP carbon and pushes the electrons in the N-C double bond in TPP entirely onto the nitrogen atom, reducing it from a positive to neutral form.
#In what is essentially the reverse of step two, the electrons push back in the opposite direction forming a new bond between the substrate carbon and another atom.  (In the case of the decarboxylases, this creates a new carbon-hydrogen bond.  In the case of transketolase, this attacks a new substrate molecule to form a new carbon-carbon bond.)
#In what is essentially the reverse of step one, the TPP-substrate bond is broken, reforming the TPP ylid and the substrate carbonyl.
  
[[File:TPP Mechanism.svg|TPP Mechanism]]
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<gallery mode=packed style="text-align:left">
Image:TPP_thiazolium.svg|The TPP thiazolium ring can be deprotonated at C2 to become an ylid.
Image:Thiamine pyrophosphate ng.png|A full view of TPP.  The arrow indicates the acidic proton.
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==See also==
* [[TPP riboswitch]]
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==External links==
*[http://www.uic.edu/classes/phar/phar332/Clinical_Cases/vitamin%20cases/thiamin/thiamin_pyrophosphate.htm UIC.edu]
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{{Enzyme cofactors}}
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{{二次利用|date=3 November 2023}}
[[Category:Cofactors]]
[[Category:Organophosphates]]
[[Category:Thiazoles]]
[[Category:Pyrimidines]]
[[Category:Thiamine]]
[[Category:Pyrophosphates]]
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