Pyruvate Dehydrogenase

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Pyruvate Dehydrogenase

 

a polyenzymatic complex that catalyzes the oxidative decarboxylation of pyruvic acid:

This reaction is the main pathway for the conversion of alpha keto acids in the tissues of animals, plants, and aerobic microorganisms; it links the two most important metabolic processes— glycolysis and the reactions of the tricarboxylic acid cycle. The vitamin derivatives thiamine pyrophosphate (TPP), coenzyme A (CoA), flavine-adenine dinucleotide (FAD), nicotinamide-adenine dinucleotide (NAD), lipoic acid, and Mg2+ ions all take part in the catalytic activity of pyruvate dehydrogenase. Magnesium ions are also necessary cofactors of the enzymes pyruvate decarboxylase, lipoyl transacetylase, and lipoyl dehydrogenase. The enzymes are present in specific quantitative relationships and fix the structure of the enzyme complex, which does not dissociate under normal conditions.

Pyruvate dehydrogenase that is extracted from animal organs and bacteria is a large protein aggregate with a molecular weight that ranges from 4,800,000 to 10,000,000 depending on its source. The complex ranges in size from 300 to 400 angstroms and is regulated by a variety of factors. In living organisms, pyruvate dehydrogenase is inhibited by phosphorylation of the decarboxylase component and reactivated upon splitting of the phosphate radical; the activity is also dependent on the energetic and hormonal state of the organism.

REFERENCE

Glemzha, A. A. “Piruvatdegidrogenaza: mekhanizm deistviia i struktura.” In the collection Uspekhi biologicheskoi khimii. Moscow, 1969.

L. S. KHAILOVA

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Competition between glucose and fatty acids for oxidation occurs at the level of the PDH complex, whose activity is decreased by PDKs.
2011) indicates that both the biotransformation of DCA and the site of its major pharmacodynamic action, the PDH complex, occur within the matrix of this organelle.
In two patients, PDHc deficiency was confirmed to result from disease-causing mutations in the E1[alpha] gene of the PDH complex. In five patients, mutation analysis of this gene did not reveal any disease-causing mutation, suggesting an involvement of other components of the PDHc.