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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.
Thiamine, also known as thiamin and vitamin B 1, is a vitamin, an essential micronutrient for humans and animals. [3] [4] It is found in food and commercially synthesized to be a dietary supplement or medication. [1] [5] Phosphorylated forms of thiamine are required for some metabolic reactions, including the breakdown of glucose and amino ...
Simplified mechanism for pyruvate dehydrogenase reaction. The TPP coenzyme is shown with abbreviated substituents. The thiamine pyrophosphate (TPP) converts to an ylide by deprotonation. The ylide attack the ketone group of pyruvate. The resulting adduct decarboxylates. The resulting 1,3-dipole reductively acetylates lipoamide-E2. [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.
[5] [9] [10] Mechanisms of the transformations are unknown. In Salmonella, HMP-P can be derived independently of purine biogenesis when AICAR is available. [11] [12] In algae, thiamine forms and precursors are scavenged by uptake from water of exogenous products from other organisms. In higher plants, thiamine biogenesis resembles that of bacteria.
Dihydrolipoyl transacetylase mechanism. 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 ...
3 Mechanism. 4 Role in disease. 5 Diagnostic use. ... acceleration of enzyme activity after the addition of thiamine pyrophosphate may be diagnostic of thiamine ...