Thiamine pyrophosphate
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| General | ||||||||||
| Surname | Thiamine pyrophosphate | |||||||||
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| Molecular formula | C 12 H 18 N 4 O 7 P 2 S | |||||||||
| Brief description |
white solid |
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| properties | ||||||||||
| Molar mass | 424.30 g mol −1 | |||||||||
| Physical state |
firmly |
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| Melting point |
240–244 ° C ( decomposition ) |
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| solubility |
good in water (220 g l −1 at 20 ° C) |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||
Thiamine pyrophosphate (TPP), also thiamine diphosphate (TDP), is a phosphate ester of thiamine (vitamin B 1 ). TPP is the coenzyme form ( cocarboxylase ) of thiamine and dominates in cells of eukaryotes compared to thiamine, as it is soon synthesized from this by the enzyme thiamine pyrophosphokinase .
The previously popular view that TPP is not transported out of the cell at all is wrong. At least one transport protein is known which is able to transport TPP in mammals.
properties
Thiamine pyrophosphate crystallizes in two hydrate forms . Both forms, a tetrahydrate and a 4,5 hydrate, form triclinic crystal lattices with the space group P1.
function
Several TPP-dependent enzymes are located at the switching points of cell metabolism. In general, TPP participates in aldehyde transfer reactions . TPP is the prosthetic group of transketolase , an enzyme of the pentose phosphate pathway . Their activity in the red blood cells is a criterion for assessing the state of supply with thiamine.
Other enzymes in which TPP acts as a coenzyme:
- Pyruvate dehydrogenase ( oxidative decarboxylation of pyruvate)
- α-ketoglutarate dehydrogenase ( citric acid cycle )
- Branched chain α-keto acid dehydrogenase (breakdown of amino acids with branched side chains)
- Acetolactate synthase (2,3-butanediol fermentation)
- Pyruvate decarboxylase ( alcoholic fermentation )
- Pyruvate oxidase
- Indole pyruvate decarboxylase
- Transketolase (pentose phosphate pathway)
Individual evidence
- ↑ a b c data sheet Cocarboxylase chloride (PDF) from Merck , accessed on January 25, 2013.
- ↑ a b Data sheet Thiamine pyrophosphate, ≥95% from Sigma-Aldrich , accessed on February 27, 2013 ( PDF ).
- ^ R. Zhao, F. Gao, Y. Wang, GA Diaz, BD Gelb, ID Goldman: Impact of the reduced folate carrier on the accumulation of active thiamin metabolites in murine leukemia cells . In: J. Biol. Chem. Volume 276 , no. 2 , January 2001, p. 1114-1118 , doi : 10.1074 / jbc.M007919200 , PMID 11038362 .
- ↑ L. de Jong, Y. Meng, J. Dent, S. Hekimi: Thiamine pyrophosphate biosynthesis and transport in the nematode Caenorhabditis elegans . In: Genetics . tape 168 , no. 2 , October 2004, p. 845-854 , doi : 10.1534 / genetics.104.028605 , PMID 15514058 , PMC 1448845 (free full text).
- ↑ J. Pletcher, M. Wood, G. Blank, W. Shin, M. Sax: Thiamine Pyrophosphate Tetrahydrate: A Structure with the Pyrophosphate Ester in an Extended Conformation. In: Acta Cryst. B 33, 1977, pp. 3349-3359.
- ↑ J. Pletcher, G. Blank, M. Wood, M. Sax: Thiamin Pyrophosphate * 4½H2O: A Second Polymorph of the Neutral Zwitterion. In: Acta Cryst. B 35, 1979, pp. 1633-1637.