Thiamine pyrophosphate

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Thiamine pyrophosphate
Thiamine diphosphate.png
Names
IUPAC name
2-[3-[(4-amino-2-methylpyrimidin-5-yl)methyl]-4-methyl-1,3-thiazol-3-ium-5-yl]ethyl phosphono hydrogen phosphate
Other names
Thiamine diphosphate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
KEGG
MeSH Thiamine+pyrophosphate
PubChem CID
UNII
  • InChI=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 Yes check.svgY
    Key: NBSUTVXQOGUTJX-UHFFFAOYSA-M Yes check.svgY
  • 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
    Key: NBSUTVXQOGUTJX-REWHXWOFAB
  • Cc2ncc(C[n+]1csc(CCOP(=O)(O)OP(=O)(O)O)c1C)c(N)n2
Properties
C12H19N4O7P2S+
Molar mass 425.314382 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Yes check.svgY  verify  (what is  Yes check.svgYX mark.svgN ?)

Thiamine pyrophosphate (TPP or ThPP), or thiamine diphosphate (ThDP), or cocarboxylase [1] 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.

Contents

Thiamine pyrophosphate is synthesized in the cytosol and is required in the cytosol for the activity of transketolase and in the mitochondria for the activity of pyruvate-, oxoglutarate- and branched chain keto acid dehydrogenases. To date, the yeast ThPP carrier (Tpc1p) the human Tpc and the Drosophila melanogaster have been identified as being responsible for the mitochondrial transport of ThPP and ThMP. [2] [3] [4] 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. [5]

TPP works as a coenzyme in many enzymatic reactions, such as:

Chemistry

The "ylide form" of TPP. TPP-ylide.svg
The "ylide form" of TPP.

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. [7] 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. [7] 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". [5] [8]

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). It achieves this in four basic steps:

  1. The carbanion of the TPP ylid nucleophilically attacks the carbonyl group on the substrate. (This forms a single bond between the TPP and the substrate.)
  2. 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.
  3. 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.)
  4. In what is essentially the reverse of step one, the TPP-substrate bond is broken, reforming the TPP ylid and the substrate carbonyl.

TPP Mechanism.svg

See also

Related Research Articles

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<span class="mw-page-title-main">Thiamine</span> Chemical compound

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<span class="mw-page-title-main">Isocitrate dehydrogenase</span> Class of enzymes

Isocitrate dehydrogenase (IDH) (EC 1.1.1.42) and (EC 1.1.1.41) is an enzyme that catalyzes the oxidative decarboxylation of isocitrate, producing alpha-ketoglutarate (α-ketoglutarate) and CO2. This is a two-step process, which involves oxidation of isocitrate (a secondary alcohol) to oxalosuccinate (a ketone), followed by the decarboxylation of the carboxyl group beta to the ketone, forming alpha-ketoglutarate. In humans, IDH exists in three isoforms: IDH3 catalyzes the third step of the citric acid cycle while converting NAD+ to NADH in the mitochondria. The isoforms IDH1 and IDH2 catalyze the same reaction outside the context of the citric acid cycle and use NADP+ as a cofactor instead of NAD+. They localize to the cytosol as well as the mitochondrion and peroxisome.

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<span class="mw-page-title-main">Transketolase</span> Enzyme involved in metabolic pathways

Transketolase is an enzyme that, in humans, is encoded by the TKT gene. It participates in both the pentose phosphate pathway in all organisms and the Calvin cycle of photosynthesis. Transketolase catalyzes two important reactions, which operate in opposite directions in these two pathways. In the first reaction of the non-oxidative pentose phosphate pathway, the cofactor thiamine diphosphate accepts a 2-carbon fragment from a 5-carbon ketose (D-xylulose-5-P), then transfers this fragment to a 5-carbon aldose (D-ribose-5-P) to form a 7-carbon ketose (sedoheptulose-7-P). The abstraction of two carbons from D-xylulose-5-P yields the 3-carbon aldose glyceraldehyde-3-P. In the Calvin cycle, transketolase catalyzes the reverse reaction, the conversion of sedoheptulose-7-P and glyceraldehyde-3-P to pentoses, the aldose D-ribose-5-P and the ketose D-xylulose-5-P.

<span class="mw-page-title-main">Pyruvate decarboxylase</span> Class of enzymes

Pyruvate decarboxylase is an enzyme that catalyses the decarboxylation of pyruvic acid to acetaldehyde. It is also called 2-oxo-acid carboxylase, alpha-ketoacid carboxylase, and pyruvic decarboxylase. In anaerobic conditions, this enzyme is participates in the fermentation process that occurs in yeast, especially of the genus Saccharomyces, to produce ethanol by fermentation. It is also present in some species of fish where it permits the fish to perform ethanol fermentation when oxygen is scarce. Pyruvate decarboxylase starts this process by converting pyruvate into acetaldehyde and carbon dioxide. Pyruvate decarboxylase depends on cofactors thiamine pyrophosphate (TPP) and magnesium. This enzyme should not be mistaken for the unrelated enzyme pyruvate dehydrogenase, an oxidoreductase, that catalyzes the oxidative decarboxylation of pyruvate to acetyl-CoA.

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<span class="mw-page-title-main">Pyruvate dehydrogenase</span> Class of enzymes

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<span class="mw-page-title-main">Pyruvate synthase</span> Class of enzymes

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<span class="mw-page-title-main">Pyruvate dehydrogenase (lipoamide) alpha 1</span> Protein-coding gene in the species Homo sapiens

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<span class="mw-page-title-main">Pyruvate dehydrogenase (lipoamide) alpha 2</span> Protein-coding gene in the species Homo sapiens

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References

  1. ↑ Pietrzak I (1995). "[Vitamin disturbances in chronic renal insufficiency. I. Water soluble vitamins]". Przegla̧D Lekarski (in Polish). 52 (10): 522–5. PMID   8834846.
  2. ↑ Marobbio, C. M. T.; Vozza, A.; Harding, M.; Bisaccia, F.; Palmieri, F.; Walker, J. E. (2002-11-01). "Identification and reconstitution of the yeast mitochondrial transporter for thiamine pyrophosphate". The EMBO Journal. 21 (21): 5653–5661. doi:10.1093/emboj/cdf583. ISSN   0261-4189. PMC   131080 . PMID   12411483.
  3. ↑ Iacopetta, Domenico; Carrisi, Chiara; De Filippis, Giuseppina; Calcagnile, Valeria M.; Cappello, Anna R.; Chimento, Adele; Curcio, Rosita; Santoro, Antonella; Vozza, Angelo (2010-03-01). "The biochemical properties of the mitochondrial thiamine pyrophosphate carrier from Drosophila melanogaster". FEBS Journal. 277 (5): 1172–1181. doi: 10.1111/j.1742-4658.2009.07550.x . ISSN   1742-4658. PMID   20121944.
  4. ↑ Lindhurst, Marjorie J.; Fiermonte, Giuseppe; Song, Shiwei; Struys, Eduard; Leonardis, Francesco De; Schwartzberg, Pamela L.; Chen, Amy; Castegna, Alessandra; Verhoeven, Nanda (2006-10-24). "Knockout of Slc25a19 causes mitochondrial thiamine pyrophosphate depletion, embryonic lethality, CNS malformations, and anemia". Proceedings of the National Academy of Sciences. 103 (43): 15927–15932. Bibcode:2006PNAS..10315927L. doi: 10.1073/pnas.0607661103 . ISSN   0027-8424. PMC   1595310 . PMID   17035501.
  5. 1 2 Pavia, Donald L., Gary M. Lampman, George S. Kritz, Randall G. Engel (2006). Introduction to Organic Laboratory Techniques (4th Ed.). Thomson Brooks/Cole. pp. 304–5. ISBN   978-0-495-28069-9.{{cite book}}: CS1 maint: multiple names: authors list (link)
  6. ↑ "PDBs for Biochemistry". Georgia State University. Archived from the original on 2011-07-16. Retrieved 2009-02-07.
  7. 1 2 Begley, Tadhg P.; Ealick, Steven E. (2010-01-01), Liu, Hung-Wen (Ben); Mander, Lew (eds.), "7.15 - Thiamin Biosynthesis", Comprehensive Natural Products II, Oxford: Elsevier, pp. 547–559, doi:10.1016/b978-008045382-8.00148-9, ISBN   978-0-08-045382-8 , retrieved 2020-12-16
  8. ↑ Voet, Donald; Judith Voet; Charlotte Pratt (2008). Fundamentals of Biochemistry . John Wiley & Sons Inc. p.  508. ISBN   978-0-470-12930-2.
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