Pyruvate dehydrogenase kinase

About: Pyruvate dehydrogenase kinase is a research topic. Over the lifetime, 4224 publications have been published within this topic receiving 161052 citations. The topic is also known as: [pyruvate dehydrogenase (lipoamide)] kinase & pyruvate dehydrogenase (lipoamide) kinase.

Stimulation of pyruvate transport in metabolizing mitochondria through changes in the transmembrane pH gradient induced by glucagon treatment of rats.

Abstract: Glucagon treatment of rats allowed the isolation of liver mitochondria with enhanced rates of pyruvate metabolism measured in either sucrose or KCl media No change in the activity of the pyruvate carrier itself was apparent, but under metabolizing conditions, use of the inhibitor of pyruvate transport, alpha-cyano-4-hydroxycinnamate, demonstrated that pyruvate transport limited the rate of pyruvate metabolism The maximum rate of transport under metabolizing conditions was enhanced by glucagon treatment Problems involved in measuring the transmembrane pH gradient under metabolizing conditions are discussed and a variety of techniques are used to estimate the matrix pH From the distribution of methylamine, ammonia and D-lactate and the Ki for inhibition by alpha-cyano-4-hydroxycinnamate it is concluded that the matrix is more acid than the medium and that the pH of the matrix rises after glucagon treatment The increase in matrix pH stimulates pyruvate transport The membrane potential, ATP concentration and O2 uptake were also increased under metabolizing conditions in glucagon-treated mitochondria These changes were correlated with a stimulation of the respiratory chain which can be observed in uncoupled mitochondria [Yamazaki (1975) J Biol Chem 250, 7924--7930] The mitochondrial Mg2+ content (mean +/- SEM) was increased from 388 +/- 12 (n = 26) to 475 +/- 20 (n = 26) ng-atoms/mg by glucagon and the K+ content from 1267 +/- 103 (n = 19) ng-atoms/mg This may represent a change in membrane potential induced by glucagon in vivo The physiological significance of these results in the control of gluconeogenesis is discussed

The potato tuber mitochondrial proteome

Abstract: Mitochondria are called the powerhouses of the cell. To better understand the role of mitochondria in maintaining and regulating metabolism in storage tissues, highly purified mitochondria were isolated from dormant potato tubers (Solanum tuberosum ‘Folva’) and their proteome investigated. Proteins were resolved by one-dimensional gel electrophoresis, and tryptic peptides were extracted from gel slices and analyzed by liquid chromatography-tandem mass spectrometry using an Orbitrap XL. Using four different search programs, a total of 1,060 nonredundant proteins were identified in a quantitative manner using normalized spectral counts including as many as 5-fold more “extreme” proteins (low mass, high isoelectric point, hydrophobic) than previous mitochondrial proteome studies. We estimate that this compendium of proteins represents a high coverage of the potato tuber mitochondrial proteome (possibly as high as 85%). The dynamic range of protein expression spanned 1,800-fold and included nearly all components of the electron transport chain, tricarboxylic acid cycle, and protein import apparatus. Additionally, we identified 71 pentatricopeptide repeat proteins, 29 membrane carriers/transporters, a number of new proteins involved in coenzyme biosynthesis and iron metabolism, the pyruvate dehydrogenase kinase, and a type 2C protein phosphatase that may catalyze the dephosphorylation of the pyruvate dehydrogenase complex. Systematic analysis of prominent posttranslational modifications revealed that more than 50% of the identified proteins harbor at least one modification. The most prominently observed class of posttranslational modifications was oxidative modifications. This study reveals approximately 500 new or previously unconfirmed plant mitochondrial proteins and outlines a facile strategy for unbiased, near-comprehensive identification of mitochondrial proteins and their modified forms.

Measurement of the Energy-Generating Capacity of Human Muscle Mitochondria: Diagnostic Procedure and Application to Human Pathology

Abstract: Background: Diagnosis of mitochondrial disorders usually requires a muscle biopsy to examine mitochondrial function. We describe our diagnostic procedure and results for 29 patients with mitochondrial disorders. Methods: Muscle biopsies were from 43 healthy individuals and 29 patients with defects in one of the oxidative phosphorylation (OXPHOS) complexes, the pyruvate dehydrogenase complex (PDHc), or the adenine nucleotide translocator (ANT). Homogenized muscle samples were used to determine the oxidation rates of radiolabeled pyruvate, malate, and succinate in the absence or presence of various acetyl Co-A donors and acceptors, as well as specific inhibitors of tricarboxylic acid cycle or OXPHOS enzymes. We determined the rate of ATP production from oxidation of pyruvate. Results: Each defect in the energy-generating system produced a specific combination of substrate oxidation impairments. PDHc deficiencies decreased substrate oxidation reactions containing pyruvate. Defects in complexes I, III, and IV decreased oxidation of pyruvate plus malate, with normal to mildly diminished oxidation of pyruvate plus carnitine. In complex V defects, pyruvate oxidation improved by addition of carbonyl cyanide 3-chlorophenyl hydrazone, whereas other oxidation rates were decreased. In most patients, ATP production was decreased. Conclusion: The proposed method can be successfully applied to the diagnosis of defects in PDHc, OXPHOS complexes, and ANT.