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

References in periodicals archive ?
Increased pyruvate levels could suggest decreased pyruvate dehydrogenase activity (due to known [As.
Two separate IPG were purified from rat liver: one (containing DCI and galactosamine) was able to activate pyruvate dehydrogenase phosphatase and the second (containing MI and glucosamine) was able to inhibit cyclic adenosine monophosphate (cAMP) kinase and adenylate cyclase, both regulatory enzymes in FFA metabolism [47].
Figure 7 shows that sublethal dose 120 PFU of IAV PR/8/34(H1N1) infection affects glucose oxidation, and reduction of energy metabolism (measured by ATP level) in skeletal muscles, liver, lung and heart, but not the brain, through reduction of mitochondrial pyruvate dehydrogenase (PDH) activity.
Autistic and schizophrenic metabolonomic patterns include low efficiency pyruvate dehydrogenase activity, mitochondrial dysfunction, dominant GABA shunt, Warburg glycolytic phenotype, hyperammonemia, hyperhomocysteinemia, porphyria, low cholesterol and bile acid levels (R.
Insulin-induced activation of pyruvate dehydrogenase complex in skeletal muscle of diabetic.
Zellweger's spectrum) Plasma lactate / 1 ml fluoride blood on A normal lactate / pyruvate ratio ice to reach laboratory pyruvate ratio [less immediately or blood than or equal to]20 collected in obtained during lactic pre-prepared perchloric acidosis suggests acid tube pyruvate dehydrogenase deficiency or a gluconeogenic defect Specific tissue or Plasma, leukocytes, Confirmation of plasma enzyme assays erythrocytes, skin specific enzyme fibroblasts or deficiency hepatocytes collected as per testing laboratory protocol Molecular gene 1 ml EDTA blood for Confirmation of genetic sequencing or nuclear gene mutations.
Increased blood lactate concentrations may also, especially in patients with sepsis, result from impaired clearance of lactate (4), inhibition of pyruvate dehydrogenase (5) and accelerated aerobic glycolysis6, at least in part related to activation of Na/K ATPase by endogenous or exogenous catecholamines (7,8).
No effect of trimetazidine was observed on glycolysis, glucose oxidation, fatty acid oxidation, or active pyruvate dehydrogenase when palmitate was substituted with 0.
It generates calcium waves in the brain and also acts as a major regulator of pyruvate dehydrogenase [5, 15].
Pyruvate dehydrogenase kinase 1 (PDK-1) phosphorylates the enzyme pyruvate dehydrogenase to inhibit its activity.
2008) demonstrated that a decrease in pyruvate dehydrogenase (PDH) activity catalyzes the conversion of pyruvate to acetyl-CoA.
2] Nonstandard abbreviations: MEGS, mitochondrial energy-generating system; PDHc, pyruvate dehydrogenase complex; TCA, tricarboxylic acid; OXPHOS, oxidative phosphorylation; DMEM, Dulbecco's modified Eagle's medium; FBS, fetal bovine serum; SETH, sucrose, EDTA, Tris-HCl, and heparin; ROCR, relative oxygen consumption rate; CS, citrate synthase; RFU, relative fluorescence units; ANT, adenine nucleotide transporter; CCCP, carbonyl cyanide 3-chlorophenyl hydrazone; mtDNA, mitochondrial DNA; ROS, reactive oxygen species.