SEARCH · PubMed Health

Results for “Pyruvate dehydrogenase”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,063 records · Page 59Linked to original sources

PubMed2002

Quantitative proteomics: the copy number of pyruvate dehydrogenase is more than 10(2)-fold lower than that of complex III in human mitochondria.

Pyruvate dehydrogenase (PDH) and complex III are two key protein complexes in mitochondrial metabolic activity. Using a novel quantitative Western blotting method, we find that PDH and complex III exist at a steady-state ratio of 1:100, 1:128 and 1:202 in HeLa cell extracts, fibroblast mitochondria and heart tissue mitochondria, respectively. This difference in stoichiometry is reflected in the immunogold labeling intensities of the two complexes and by the much more sparse distribution of PDH in fluorescence microscopy. In Rho0 fibroblasts there is a 64% reduction of complex III but the concentration of PDH remains the same as wild-type.

Blotting, Western↗

PubMed1993

E1 pyruvate dehydrogenase deficiency in a child with motor neuropathy.

We report the case of a boy who developed a motor neuropathy during infectious episodes at 18 mo and 3 y of age. When he was 7 y old, he suffered persistent weakness and areflexia; his resting lactate and pyruvate values were 3.65 mM and 398 microM, respectively (controls: 1.1 +/- 0.3 mM and 90 +/- 22 microM), and an exercise test demonstrated a lactic acidosis (13.6 mM; controls: 6.4 +/- 1.3 mM) with a high pyruvate level (537 microM; controls: 176 +/- 15 microM) and a low lactate/pyruvate ratio (24.2; controls: 35 +/- 2). The results of polarographic studies on muscle mitochondria suggested a defect in pyruvate oxidation (pyruvate 17 ng atom O/min/mg protein; controls: 115 +/- 42), whereas glutamate, palmitoylcarnitine, and succinate were good respiratory substrates. The activity of total pyruvate dehydrogenase complex (PDHC) in muscle mitochondria and in fresh mononuclear cells was markedly decreased (9.7 and 0.054 nmol 14CO2/min/mg protein, respectively; controls: 123 +/- 4.5 and 0.733 +/- 0.03, respectively). Immunochemical analysis in muscle mitochondria demonstrated an absence of the alpha and beta E1 PDHC subunits. After 2 y of treatment with 500 mg/d thiamine, the patient was clinically improved. A genetic study of the main regions of mutations (exon 10 and 11) in the X chromosome encoding for the E1 alpha subunit of PDHC did not show any mutation. These data indicate that, although genetically different, this case enters in a very rare category of patients with PDHC deficiency without cerebral dysfunction and improved by thiamine + L-carnitine therapy.

Base Sequence↗

PubMed1996

A putative pyruvate dehydrogenase alpha subunit gene from Trypanosoma cruzi.

A full-length DNA clone encoding a putative pyruvate dehydrogenase alpha subunit (E1 alpha) gene was isolated from a Trypanosoma cruzi (RA strain) DNA library. Sequencing of this clone revealed it to encode a 378 amino acid protein (M(r) 42774) with high sequence similarity to E1 alpha obtained from different sources. The highest score is obtained with human E1 alpha: 43,3% similarity. Southern blot analysis is consistent with the existence of a single copy of this putative T. cruzi E1 alpha gene per haploid genome in different parasite strains. Expression of this gene was demonstrated by Northern blot analysis and its trans-splicing acceptor site was identified by Polymerase Chain Reaction-mediated amplification of its cDNA.

Amino Acid Sequence↗

PubMed1981

Rotational diffusion of eosin-labeled pyruvate dehydrogenase complex of Escherichia coli.

The enzymatically reduced lipoyl residues of the transacetylase component of the pyruvate dehydrogenase complex from Escherichia coli were labeled with eosin maleimide. Using eosin as triplet probe, triplet-triplet absorption dichroism measurements were performed to obtain rotational correlation times of the complex in the microsecond time domain. It was found that the hydrodynamic properties determined from the correlation times are in very good agreement with those obtained with other methods of different origin. The results can be fully explained by eosin molecules rotating with the whole complex, which consists of a mixture of heavy (60 S) and light (20 S) particles. Since no independent mobility could be detected it is suggested that the (charged) chromophoric group is folded against the protein surface. Labeling with excess eosin maleimide tends to destabilize the complex, since the longer correlation time (60 S) decreases and the contribution of the shorter correlation time (20 S) becomes more significant upon labeling.

Coloring Agents↗

PubMed2000

The abundance of mRNAs for pyruvate dehydrogenase kinase isoenzymes in brain regions of young and aged rats.

The abundance of mRNAs for pyruvate dehydrogenase kinase (PDK) isoenzymes in four brain regions of young (10 wk) and aged (50 wk) rats was investigated by reverse transcription-polymerase chain reaction (RT-PCR). The mRNAs for PDK1, 2, and 4 were detected in all the regions examined. The level of PDK2 mRNA was the most abundant among the isoenzymes in all the brain regions when judged from the PCR cycles. The level of PDK1 mRNA was relatively high in cerebellum and cerebral cortex compared to medulla oblongata and hippocampus. Aging decreased the levels of mRNAs for PDK1 and 2 in cerebellum and increased the PDK2 mRNA in hippocampus and cerebral cortex. The level of PDK4 mRNA was not affected by aging. These results provide the first evidence suggesting that there is the regional difference in the abundance of mRNAs for PDK isoenzymes in rat brain and that the levels of mRNAs for the isoenzymes were affected by aging.

Aging↗

PubMed1987

The regulation of adipose tissue pyruvate dehydrogenase activity of dietary fiber.

In vitro studies have established that insulin enhances the oxidation of pyruvate to acetyl CoA by the stimulation of mitochondrial pyruvate dehydrogenase (PDH) activity through plasma membrane binding response (Jarett and Seals 1979; Kiechle, Jarett, Dennis and Kotagal 1980). In the present study adipose tissue PDH activity was utilized as a marker for insulin responsiveness. The metabolic response of this enzyme to exogenous insulin was employed to test the hypothesis that dietary fiber enhances tissue responsiveness to insulin using adipose tissue from male weanling Sprague Dawley rats. Eight groups of rats (n = 5 per group) were fed ad libitum various diets containing different levels of cellulose and protein as already reported elsewhere (Ogunwole, Knight, Adkins, Thomaskutty and Pointer 1985). Percent insulin stimulation of PDH from basal activity (PDS) was utilized as an index of insulin responsiveness. Compared to all fiber treated groups, both basal (PDB) and insulin stimulated (PDI) activities were significantly lower (P less than 0.05) in the fiber free groups at both low (10%) and high (20%) protein levels. At all fiber levels tested (0, 5, 15 and 30%) protein intake resulted in a significant increase in both PDB and PDI. Gradual increase in cellulose intake resulted in a biphasic increase in PDS in both protein groups at the 5% and 30% fiber levels. PDS was higher (P less than 0.05) in the 10% protein groups than the 20% protein group at all fiber levels tested. A significant interaction effect of protein and fiber was observed on PDB (P less than 0.001) and PDI (P less than 0.04) when caloric intake was held constant as a covariate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗

PubMed1995

Metabolic engineering in Escherichia coli: lowering the lipoyl domain content of the pyruvate dehydrogenase complex adversely affects the growth rate and yield.

Isogenic strains of Escherichia coli W3110 containing pyruvate dehydrogenase complexes with three (wild-type), two or one lipoyl domains per lipoate acetyltransferase (E2p) chain, were constructed. The maximum growth rates (mumax) for batch cultures growing in minimal medium containing different carbon sources showed that reducing the number of lipoyl domains adversely mumax value of the mutant containing one lipoyl domain per E2p chain was restored by the presence of compatible multicopy plasmids encoding PDH complexes with either one or three lipoyl domains per E2p chain. In glucose-limited chemostat cultures the protein contents of all strains were similar and substrate carbon was totally accounted for in the biomass and CO2 produced. However, the carbon efficiencies (percentage carbon conversion to biomass) were significantly lower when the lipoyl domain content of the E2p subunit was reduced from three to one. Similarly, the cellular maintenance energy (m(e)) and the maximum growth yield (Ymax) were lower in bacteria containing PDH complexes with fewer than three lipoyl domains per E2p chain. Wild-type values were restored by supplementing the medium with either casamino acids (0.01%) or acetate (up to 0.1 mM). The lower growth efficiencies of the mutants were further confirmed in competition experiments where equal numbers of genetically marked (NalR) mutant and wild-type bacteria were used to inoculate glucose-limited chemostat cultures (dilution rate 0.075 h-1). The mutants with one or two lipoyl domains per E2p chain were washed out, whereas in controls, the initial ratio of wild-type (Nals) to reconstructed wild-type (NalR) bacteria was maintained over 50 generations.

Acetyltransferases↗

PubMed1995

A library of monoclonal antibodies to Escherichia coli K-12 pyruvate dehydrogenase complex. A biochemical analysis and their ability to inhibit the enzyme complex.

A library of monoclonal antibodies to K-12 Escherichia coli pyruvate dehydrogenase complex (PDHc) and its pyruvate decarboxylating (EC 1.2.4.1; E1) subunit is reported. 21 monoclonal antibodies were generated, and 20 were investigated, of which 9 were elicited to PDHc and 11 to pure E1 subunit; 19 were of the IgG1 isotype and one of the IgG3 isotype. According to an enzyme immunoassay, all 20 of the monoclonal antibodies bound the PDHc, and 17 bound the E1 subunit. According to Western blot analysis, 14 of the 19 monoclonal antibodies bound to the E1 subunit. The monoclonal antibodies inhibited PDHc from 0 to > 98%. The six monoclonal antibodies that displayed greater than 30% inhibition of E. coli PDHc were unable to inhibit porcine heart PDHc nor did they bind porcine heart PDHc according to dot blot analysis. Radiolabeling gave binding constants ranging from 5 to 10 x 10(8) M-1 on these six monoclonal antibodies, with greater than 80% of maximal inhibition achieved in less than 1 min. One of the six, 18A9, gave > 98% inhibition, required two antibodies/E1 subunit for maximum inhibition, and was shown to be a non-competitive inhibitor. Monoclonal antibody 15A9 was shown to counteract GTP-induced inhibition, while 1F2 influenced the conformation of E1, allowing two antibodies, which did not previously bind E1, to bind to it. A new mechanism-based kinetic assay is presented that is specific for the E1 component of 2-keto acid dehydrogenases. This assay confirmed that the three most strongly inhibitory monoclonal antibodies specifically inhibited the E1 function while antibody 1F2 led to enhanced activity, suggesting an induced conformational change in PDHc or in E1.

Animals↗

PubMed1987

Muscle involvement in pyruvate dehydrogenase complex (PDHC) deficiency.

Muscle biopsies from a 13-month-old female infant with a delay in developmental milestones, lactic acidosis and visual disturbance, and a 6 year-old female with frequent epileptic fits are described. Biochemical studies of biopsied muscles and skin fibroblasts demonstrated markedly decreased pyruvate dehydrogenase complex (PDHC) activity to about 16% of normal value. Muscle histochemistry in both patients showed disorganized intermyofibrillar networks containing large diformazan granules on NADH-TR, small angulated fibers with high nonspecific esterase (NSE) activity and basophilic fibers. Ragged-red fibers and increased lipid droplet accumulation were absent. Patient 1 had increased numbers of type 2C fibers (11.3%) and mild fiber type grouping. On electron microscopy, most mitochondria were nearly normal. There were focal aggregates of mildly enlarged mitochondria in the subsarcolemmal areas in both patients. Morphometric study showed that the mean mitochondrial size and the mitochondrial percentage of fiber volume were not significantly different amongst patients and normal controls.

Child↗

PubMed2004

Rapid upregulation of pyruvate dehydrogenase kinase activity in human skeletal muscle during prolonged exercise.

Prolonged moderate-intensity exercise is characterized by a progressive reduction in carbohydrate oxidation and concomitant increase in fat oxidation. Pyruvate dehydrogenase (PDH) controls the entry of pyruvate into oxidative pathways and is a rate-limiting enzyme for carbohydrate metabolism. PDH is controlled by the activities of a kinase (PDK, inhibitory) and phosphatase (stimulatory). To test the hypothesis that increased PDK activity was associated with decreased PDH activity and carbohydrate oxidation during an acute exercise bout, seven recreationally active men completed 4 h of cycle exercise at 55% peak oxygen consumption. Muscle samples were obtained before and at 10 min and 4 h of exercise for the measurement of PDH activity and the extraction of intact mitochondria for the measurements of PDK activity and PDK-2 and PDK-4 protein expression. Carbohydrate oxidation was reduced (P < 0.05) with exercise duration. Muscle glycogen content was lower (P < or = 0.05) at 4 h compared with rest and there was no change in muscle pyruvate content from 10 to 240 min during exercise (10 min: 0.28 +/- 0.05; 240 min: 0.35 +/- 0.09 mmol/kg dry muscle). PDH activity increased (P < 0.05) above resting values at 10 min (2.86 +/- 0.26 mmol.min(-1).kg wet muscle(-1)), but was lower than 10 min after 4 h (2.23 +/- 0.24 mmol.min(-1).kg wet muscle(-1)) of exercise. PDK-2 and PDK-4 protein expression was not different from rest at 10 min and 4 h of exercise. PDK activity at rest averaged 0.081 +/- 0.016 min(-1), was similar at 10 min, and increased (P < 0.05) to 0.189 +/- 0.013 min(-1) at 4 h. Although reduced glycolytic flux may have played a role in decreasing carbohydrate oxidation, the results suggest that increased PDK activity contributed to the reduction in PDH activity and carbohydrate oxidation late in prolonged exercise. The increased PDK activity was independent of changes in intra-mitochondrial effectors, and PDK-2 and PDK-4 protein content, suggesting that it was caused by a change in the specific activity of the existing kinases.

Adult↗

PubMed1986

Hepatic glycogen synthesis on carbohydrate re-feeding after starvation. A regulatory role for pyruvate dehydrogenase in liver and extrahepatic tissues.

Glucose administration to 48 h-starved rats increased hepatic glucose, lactate, pyruvate and glycogen concentrations and re-activated PDH (pyruvate dehydrogenase complex) in kidney, but not in heart or liver. Dichloroacetate together with glucose re-activated PDH in all three tissues, decreased hepatic lactate and pyruvate concentrations and impaired glycogen resynthesis. Thus on re-feeding, delayed PDH re-activation is important for provision of precursors for hepatic glyconeogenesis.

Animals↗

PubMed2002

Enhanced pyruvate dehydrogenase activity does not affect muscle O2 uptake at onset of intense exercise in humans.

It has been proposed that the activation state of pyruvate dehydrogenase (PDH) may influence the rate of skeletal muscle O2 uptake during the initial phase of exercise; however, this has not been directly tested in humans. To remedy this, we used dichloroacetate (DCA) infusion to increase the active form of PDH (PDH(a)) and, subsequently, measured leg O2 uptake and markers of anaerobic ATP provision during conditions of intense dynamic exercise, when the rate of muscle O2 uptake would be very high. Six subjects performed brief bouts of one-legged knee-extensor exercise at approximately 110% of thigh peak O2 uptake (65.3 +/- 3.7 W) on several occasions: under noninfused control (Con) and DCA-supplemented conditions. Needle biopsy samples from the vastus lateralis muscle were obtained at rest and after 5 s, 15 s, and 3 min of exercise during both experimental conditions. In addition, thigh blood flow and femoral arteriovenous differences for O2 and lactate were measured repeatedly during the 3-min work bouts (Con and DCA) to calculate thigh O2 uptake and lactate release. After DCA administration, PDH(a) was four- to eightfold higher (P < 0.05) than Con at rest, and PDH(a) remained approximately 130% and 100% higher (P < 0.05) after 5 and 15 s of exercise, respectively. There was no difference between trials after 3 min. Despite the marked difference in PDH(a) between trials at rest and during the initial phase of exercise, thigh O2 uptake was the same. In addition, muscle phosphocreatine utilization and lactate production were similar after 5 s, 15 s, and 3 min of exercise in DCA and Con. The present findings demonstrate that increasing PDH(a) does not alter muscle O2 uptake and anaerobic ATP provision during the initial phase of intense dynamic knee-extensor exercise in humans.

Adult↗

PubMed2004

Pyruvate dehydrogenase E1alpha subunit deficiency in a female patient: evidence of antenatal origin of brain damage and possible etiology of infantile spasms.

Enlargement of the lateral ventricles and atrophy of the brain were documented ultrasonographically in utero at as early as 28th week of gestation in a female patient with lactic acidosis due to deficiency of the pyruvate dehydrogenase E1alpha subunit, demonstrating that the changes characteristic of this disease can occur antenatally. The mechanism of infantile spasms in this disease may be linked to mosaicism of the brain cells involving the normal enzyme and the mutant enzyme.

Electroencephalography↗

PubMed1995

Interaction of component enzymes with the peripheral subunit-binding domain of the pyruvate dehydrogenase multienzyme complex of Bacillus stearothermophilus: stoichiometry and specificity in self-assembly.

The interaction between the pyruvate decarboxylase (E1) component and a di-domain (lipoyl domain plus peripheral subunit-binding domain) from the dihydrolipoyl acetyltransferase (E2) component of the Bacillus stearothermophilus pyruvate dehydrogenase multienzyme complex was investigated. Only 1 mol of di-domain (binding domain) was bound to 1 mol of heterotetrameric E1 (alpha 2 beta 2) and the binding was without effect on the kinetic activity of E1. Similarly, the di-domain bound to separate E1 beta subunits at a maximal polypeptide chain ratio of 1:2, but no detectable interaction was found with the E1 alpha subunit. However, addition of the monomeric E1 alpha subunit to an E1 beta-di-domain complex generated a fully functional E1 (alpha 2 beta 2)-di-domain complex, indicating that the E1 beta subunit plays the critical part in binding the E1 component to the di-domain and suggesting that no chaperonin is needed in vitro to promote the assembly of the three separate proteins. Mixing the E1 and dihydrolipoyl dehydrogenase (E3) components in the presence of di-domain revealed that E1 and E3 cannot bind simultaneously to the same molecule of di-domain, a new feature of the assembly pathway and an important factor in determining the ultimate structure of the assembled enzyme complex.

Binding Sites↗

PubMed1990

Three genes for enzymes of the pyruvate dehydrogenase complex map to human chromosomes 3, 7, and X.

The genes for three proteins of the pyruvate dehydrogenase (PDH) complex have been assigned to human chromosomes by Southern analysis of a panel of human-rodent somatic cell hybrid DNAs with cDNA probes for these genes. PDH-E1 alpha has been localized on human chromosome 3p13-q23. The assignments of lipoamide dehydrogenase(E3) and PDH-E1 alpha [corrected] to chromosomes 7 and Xp, respectively, have been confirmed. Restrictive-fragment-length polymorphisms have been identified with E3, which will permit further localization of this gene by genetic linkage analysis.

Animals↗

PubMed2004

Azorhizobium caulinodans electron-transferring flavoprotein N electrochemically couples pyruvate dehydrogenase complex activity to N2 fixation.

Azorhizobium caulinodans thermolabile point mutants unable to fix N2 at 42 degrees C were isolated and mapped to three, unlinked loci; from complementation tests, several mutants were assigned to the fixABCX locus. Of these, two independent fixB mutants carried missense substitutions in the product electron-transferring flavoprotein N (ETFN) alpha-subunit. Both thermolabile missense variants Y238H and D229G mapped to the ETFNalpha interdomain linker. Unlinked thermostable suppressors of these two fixB missense mutants were identified and mapped to the lpdA gene, encoding dihydrolipoamide dehydrogenase (LpDH), immediately distal to the pdhABC genes, which collectively encode the pyruvate dehydrogenase (PDH) complex. These two suppressor alleles encoded LpDH NAD-binding domain missense mutants G187S and E210G. Crude cell extracts of these fixB lpdA double mutants showed 60-70% of the wild-type PDH activity; neither fixB lpdA double mutant strain exhibited any growth phenotype at the restrictive or the permissive temperature. The genetic interaction between two combinations of lpdA and fixB missense alleles implies a physical interaction of their respective products, LpDH and ETFN. Presumably, this interaction electrochemically couples LpDH as the electron donor to ETFN as the electron acceptor, allowing PDH complex activity (pyruvate oxidation) to drive soluble electron transport via ETFN to N2, which acts as the terminal electron acceptor. If so, then, the A. caulinodans PDH complex activity sustains N2 fixation both as the driving force for oxidative phosphorylation and as the metabolic electron donor.

Azorhizobium caulinodans↗

PubMed1989

Effects of re-feeding after prolonged starvation on pyruvate dehydrogenase activities in heart, diaphragm and selected skeletal muscles of the rat.

We investigated the capacity for pyruvate oxidation in skeletal muscle, diaphragm and heart after starvation and re-feeding. Starvation for 48 h decreased pyruvate dehydrogenase (PDH) activity in soleus (by 47%), extensor digitorum longus (64%), gastrocnemius (86%), diaphragm (87%), adductor longus (90%), tibialis anterior (92%) and heart (99%). Chow re-feeding increased PDH activity in all muscles to 43-78% of the fed value within 2 h. However, complete re-activation was not observed for at least 4-6 h, during which time hepatic glycogen was replenished. We discuss the importance of muscle PDH activity in relation to sparing carbohydrate for hepatic glycogen synthesis.

Animals↗

PubMed1980

Pyruvate dehydrogenase complex from germinating castor bean endosperm.

Subcellular organelles from castor bean (Ricinus communis) endosperm were isolated on discontinuous sucrose gradients from germinating seeds which were 1 to 7 days postimbibition. Marker enzyme activities of the organelles were measured (fumarase, catalase, and triose phosphate isomerase) and the homogeneity of the organelle fractions was examined by electron microscopy. Pyruvate dehydrogenase complex activity was measured only in the mitochondrial fraction and attempts to activate or release the enzyme from the proplastid were not successful. A pathway is proposed for the most efficient use of endosperm carbon for de novo fatty acid biosynthesis that does not require the presence of the pyruvate dehydrogenase complex in the proplastid to provide acetyl-coenzymeA.

Journal Article↗