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Thiamine pyrophosphate is a cofactor that is present in all living systems, in which it catalyzes several biochemical reactions. 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 ...
It serves as a riboswitch [1] [2] that binds thiamine pyrophosphate (TPP) directly and modulates gene expression through a variety of mechanisms in archaea, bacteria and eukaryotes. [3] [4] [5] TPP is the active form of thiamine (vitamin B 1), an essential coenzyme synthesised by coupling of pyrimidine and thiazole moieties in bacteria.
[12] [13] In the body, thiamine can form derivatives; the most well-characterized of which is thiamine pyrophosphate (TPP), a coenzyme in the catabolism of sugars and amino acids. [3] The chemical structure consists of an aminopyrimidine and a thiazolium ring linked by a methylene bridge. The thiazole is substituted with methyl and hydroxyethyl ...
Pyruvate decarboxylation requires a few cofactors in addition to the enzymes that make up the complex. The first is thiamine pyrophosphate (TPP), which is used by pyruvate dehydrogenase to oxidize pyruvate and to form a hydroxyethyl-TPP intermediate. This intermediate is taken up by dihydrolipoyl transacetylase and reacted with a second ...
E 1 uses thiamine pyrophosphate (TPP) as a catalytic cofactor. E 1 catalyzes both the decarboxylation of the α-ketoacid and the subsequent reductive acylation of the lipoyl moiety (another catalytic cofactor) that is covalently bound to E 2.
Initially, pyruvate and thiamine pyrophosphate (TPP or vitamin B 1) are bound by pyruvate dehydrogenase subunits. [1] The thiazolium ring of TPP is in a zwitterionic form, and the anionic C2 carbon performs a nucleophilic attack on the C2 (ketone) carbonyl of pyruvate.
The conversion requires the coenzyme thiamine pyrophosphate. Pyruvate dehydrogenase is usually encountered as a component, referred to as E1, of the pyruvate dehydrogenase complex (PDC). PDC consists of other enzymes, referred to as E2 and E3. Collectively E1-E3 transform pyruvate, NAD +, coenzyme A into acetyl-CoA, CO 2, and NADH.
There are three different coenzymes required throughout the 5 steps that this complex carries out: thiamine pyrophosphate (TPP), lipoamide, and coenzyme A. This step is only one of the central metabolic pathway carried out by eukaryotes, in which glucose is oxidized to form carbon dioxide, water, and ATP.