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Complex IV (complex + iv)
Selected AbstractsPseudomonas fluorescens orchestrates a fine metabolic-balancing act to counter aluminium toxicityENVIRONMENTAL MICROBIOLOGY, Issue 6 2010Joseph Lemire Summary Aluminium (Al), an environmental toxin, is known to disrupt cellular functions by perturbing iron (Fe) homeostasis. However, Fe is essential for such metabolic processes as the tricarboxylic acid (TCA) cycle and oxidative phosphorylation, the two pivotal networks that mediate ATP production during aerobiosis. To counter the Fe conundrum induced by Al toxicity, Pseudomonas fluorescens utilizes isocitrate lyase and isocitrate dehydrogenase-NADP dependent to metabolize citrate when confronted with an ineffective aconitase provoked by Al stress. By invoking fumarase C, a hydratase devoid of Fe, this microbe is able to generate essential metabolites. To compensate for the severely diminished enzymes like Complex I, Complex II and Complex IV, the upregulation of a H2O-generating NADH oxidase enables the metabolism of citrate, the sole carbon source via a modified TCA cycle. The overexpression of succinyl-CoA synthetase affords an effective route to ATP production by substrate-level phosphorylation in the absence of O2. This fine metabolic balance enables P. fluorescens to survive the dearth of bioavailable Fe triggered by an Al environment, a feature that may have potential applications in bioremediation technologies. [source] Syntheses, Spectroscopic Studies, and Crystal Structures of Chiral [Rh(aminocarboxylato)(,4 -cod)] and Chiral [Rh(amino alcohol)(,4 -cod)](acetate) Complexes with an Example of a Spontaneous Resolution of a Racemic Mixture into Homochiral Helix-EnantiomersEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2006Mohammed Enamullah Abstract The dimeric complex acetato(,4 -cycloocta-1,5-diene)rhodium(I), [Rh(O2CMe)(,4 -cod)]2 (cod = cycloocta-1,5-diene), reacts with amino acids [HAA = L -alanine, (S)-2-amino-2-phenylacetic acid (L -phenylglycine), N -methylglycine, and N -phenylglycine] and with the amino alcohol (S)-2-amino-2-phenylethanol to afford the aminocarboxylato(,4 -cycloocta-1,5-diene)rhodium(I) complexes [Rh(AA)(,4 -cod)] (AA = deprotonated amino acid = aminocarboxylato ligand) and [(S)-2-amino-2-phenylethanol](,4 -cycloocta-1,5-diene)rhodium(I) acetate, [Rh{(S)-HOCH2,CH(Ph)-NH2}(,4 -cod)](O2CMe) (V). The complexes are characterized by IR, UV/Vis, 1H/13C NMR and mass spectroscopy. The achiral N -phenylglycine ligand gives a chiral N -phenylglycinato complex [Rh(O2C,CH2,NHPh)(,4 -cod)] (IV) with the amine nitrogen atom becoming the stereogenic center upon metal coordination. Complex IV crystallizes in the tetragonal, chiral space group P43 and the crystal structure reveals twofold spontaneous resolution of a racemic mixture into homochiral helix-enantiomers. The investigated crystal contained only one type of helix, namely (left-handed or M- ) 43 -helical chains. This is traced first to an intermolecular N,H···O hydrogen bonding from the stereogenic amino group to a neighboring unligated carboxyl oxygen atom that connects only molecules of the same (R)-configuration into (left-handed or M- ) 43 -helical chains. This intrachain homochirality is supplemented, secondly, by the interlocking of adjacent chains with their corrugated van der Waals surface to allow for an interchain transmission of the sense of helicity, building the single crystal from the same homochiral helix-enantiomer. The enantiomeric amino alcohol complex V crystallizes in the monoclinic, noncentrosymmetric (Sohncke) space group P21. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Mitochondrial formation of reactive oxygen speciesTHE JOURNAL OF PHYSIOLOGY, Issue 2 2003Julio F. Turrens The reduction of oxygen to water proceeds via one electron at a time. In the mitochondrial respiratory chain, Complex IV (cytochrome oxidase) retains all partially reduced intermediates until full reduction is achieved. Other redox centres in the electron transport chain, however, may leak electrons to oxygen, partially reducing this molecule to superoxide anion (O2,,). Even though O2,, is not a strong oxidant, it is a precursor of most other reactive oxygen species, and it also becomes involved in the propagation of oxidative chain reactions. Despite the presence of various antioxidant defences, the mitochondrion appears to be the main intracellular source of these oxidants. This review describes the main mitochondrial sources of reactive species and the antioxidant defences that evolved to prevent oxidative damage in all the mitochondrial compartments. We also discuss various physiological and pathological scenarios resulting from an increased steady state concentration of mitochondrial oxidants. [source] Supercomplex organization of the mitochondrial respiratory chain and the role of the Coenzyme Q pool: Pathophysiological implicationsBIOFACTORS, Issue 1-4 2005Maria Luisa Genova Abstract In this review we examine early and recent evidence for an aggregated organization of the mitochondrial respiratory chain. Blue Native Electrophoresis suggests that in several types of mitochondria Complexes I, III and IV are aggregated as fixed supramolecular units having stoichiometric proportions of each individual complex. Kinetic evidence by flux control analysis agrees with this view, however the presence of Complex IV in bovine mitochondria cannot be demonstrated, presumably due to high levels of free Complex. Since most Coenzyme Q appears to be largely free in the lipid bilayer of the inner membrane, binding of Coenzyme Q molecules to the Complex I-III aggregate is forced by its dissociation equilibrium; furthermore free Coenzyme Q is required for succinate-supported respiration and reverse electron transfer. The advantage of the supercomplex organization is in a more efficient electron transfer by channelling of the redox intermediates and in the requirement of a supramolecular structure for the correct assembly of the individual complexes. Preliminary evidence suggests that dilution of the membrane proteins with extra phospholipids and lipid peroxidation may disrupt the supercomplex organization. This finding has pathophysiological implications, in view of the role of oxidative stress in the pathogenesis of many diseases. [source] Focused proteomics: Monoclonal antibody-based isolation of the oxidative phosphorylation machinery and detection of phosphoproteins using a fluorescent phosphoprotein gel stainELECTROPHORESIS, Issue 15 2004James Murray Abstract We have raised monoclonal antibodies capable of immunocapturing all five complexes involved in oxidative phosphorylation for evaluating their post-translational modifications. Complex I (NADH dehydrogenase), complex II (succinate dehydrogenase), complex III (cytochrome c reductase), complex IV (cytochrome c oxidase), and complex V (F1F0 ATP synthase) from bovine heart mitochondria were obtained in good yield from small amounts of tissue in more than 90% purity in one step. The composition and purity of the complexes was evaluated by Western blotting using monoclonal antibodies against individual subunits of the five complexes. In this first study, the phosphorylation state of the proteins without inducing phosphorylation or dephosphorylation was identified by using the novel Pro-Q Diamond phosphoprotein gel stain. The major phosphorylated components were the same as described before in sucrose gradient enriched complexes. In addition a few additional potential phosphoproteins were observed. Since the described monoclonal antibodies show cross reactivity to human proteins, this procedure will be a fast and efficient way of studying post-translational modifications in control and patient samples using only small amounts of tissue. [source] Different pathophysiological mechanisms of intramitochondrial iron accumulation in acquired and congenital sideroblastic anemia caused by mitochondrial DNA deletionEUROPEAN JOURNAL OF HAEMATOLOGY, Issue 2 2006Thomas Matthes Abstract:, Sideroblastic anemias (SA) are characterized by iron accumulation in the mitochondria of erythroblasts. Although we have evidence of mitochondrial gene alterations in sporadic congenital cases, the origin of acquired forms [refractory anemia with ring sideroblasts (RARS)], is still largely unknown. Here, we report the analysis of respiratory chain function in a patient with a large mitochondrial deletion and in patients with RARS. A young boy with SA showed symptoms typical of a mitochondrial disease with metabolic acidosis, muscle weakness and cerebral involvement. His bone marrow DNA was analyzed for the presence of mitochondrial deletions. We found a new mitochondrial (mt)DNA deletion spanning 3614 bp and including all the mt genes encoding complex IV, plus ATPase 6 and 8, and several transfer (t)RNAs. All tissues analyzed (liver, skeletal muscle, brain, pancreas) showed a heteroplasmic distribution of this mutant DNA. Bone marrow homogenates were obtained from five patients with RARS and from three patients with normal bone marrow and respiratory chain function assayed by spectrophotometric analysis. Cytochrome c oxidase (CCO) activity was greatly reduced in the patient's bone marrow. In contrast, CCO activity and global respiratory chain function were conserved in patients with RARS. We conclude that deficient CCO activity secondary to mtDNA deletions is related to intramitochondrial iron accumulation, as in our patient or in those with Pearson's syndrome, whereas other mechanisms, e.g. nuclear DNA mutations, have to be proposed to be involved in the acquired forms of SA. [source] Defective hepatic mitochondrial respiratory chain in patients with nonalcoholic steatohepatitisHEPATOLOGY, Issue 4 2003M.D., Mercedes Pérez-Carreras Ph.D. Mitochondrial dysfunction might play a central role in the pathogenesis of nonalcoholic steatohepatits (NASH). The aims of this study were to evaluate whether free fatty acid (FFA) transport into the mitochondria or the activity of mitochondria respiratory chain (MRC) complexes are impaired in NASH. In patients with NASH and control subjects, we measured free carnitine, short-chain acylcarnitine (SCAC) and long-chain acylcarnitine (LCAC) esters, carnitine palmitoyltransferase (CPT) activity, and MRC enzyme activity in liver tissue as well as serum concentration of tumor necrosis factor , (TNF-,), homeostatic metabolic assessment of insulin resistance (HOMAIR), and body mass index (BMI). In patients with NASH, the LCAC/free carnitine ratio was significantly increased and the SCAC/free carnitine ratio was decreased. In patients with NASH, the activity of the MRC complexes was decreased to 63% ± 20% (complex I), 58.5% ± 16.7% (complex II), 70.6% ± 10.3% (complex III), 62.5% ± 13% (complex IV), and 42.4% ± 9.1% (adenosine triphosphate synthase) of the corresponding control values. Activity of these complexes correlated significantly with serum TNF-, and HOMAIR. Serum TNF-, (36.3 ± 23.1 pg/mL), HOMAIR (4.5 ± 2.38), and BMI (29.9 ± 3.5 kg/m2) values were significantly increased in patients with NASH. In conclusion, activities of MRC complexes were decreased in liver tissue of patients with NASH. This dysfunction correlated with serum TNF-,, insulin resistance, and BMI values. (Hepatology 2003;38:999,1007). [source] Oxidative stress and metabolism in animal model of colitis induced by dextran sulfate sodiumJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 11 2007Carlos R Damiani Abstract Background and Aim:, Ulcerative colitis is a chronic inflammatory disease of the gastrointestinal tract. Its etiology remains unclear, but it appears to result from a dysregulated immune response, with infiltration of phagocytic leukocytes into the mucosal interstitium. The production and release of reactive oxygen species by immune cells seems to play a crucial role in physiopathology of colitis. The aim of this work was to evaluate the effects of N-acetylcysteine (NAC) and deferoxamine (DFX) in the treatment of colitis induced by dextran sulfate sodium (DSS). Methods:, The effects of NAC and DRX on rats with DSS-induced colitis were determined by measuring intestinal parameters of oxidative stress and mitochondrial function, inflammatory response and bowel histopathological alterations. Results:, DSS increased white blood cells count and NAC and DFX did not prevent this effect. However, DSS increased mitochondrial respiratory chain complex IV in colon of rats and NAC and DFX prevented this alteration. In addition, thiobarbituric acid reactive substances were increased in colon of DSS-treated rats. NAC and DFX, when taken together, prevented this effect. Complex II and succinate dehydrogenase were not affected by DSS, as protein carbonyl content. Conclusions:, It is speculated that NAC and DFX might be useful for treatment of colitis, but further research is necessary to clarify these effects. [source] In Vivo Labeling of Mitochondrial Complex I (NADH:UbiquinoneOxidoreductase) in Rat Brain Using [3H]DihydrorotenoneJOURNAL OF NEUROCHEMISTRY, Issue 6 2000Deepa J. Talpade Abstract: Defects in mitochondrial energy metabolism have beenimplicated in several neurodegenerative disorders. Defective complex I(NADH:ubiquinone oxidoreductase) activity plays a key role in Leber'shereditary optic neuropathy and, possibly, Parkinson's disease, but there isno way to assess this enzyme in the living brain. We previously described anin vitro quantitative autoradiographic assay using[3H]dihydrorotenone ([3H]DHR) binding to complex I. Wehave now developed an in vivo autoradiographic assay for complex I using[3H]DHR binding after intravenous administration. In vivo[3H]DHR binding was regionally heterogeneous, and brain uptake wasrapid. Binding was enriched in neurons compared with glia, and white matterhad the lowest levels of binding. In vivo [3H]DHR binding wasmarkedly reduced by local and systemic infusion of rotenone and was enhancedby local NADH administration. There was an excellent correlation betweenregional levels of in vivo [3H]DHR binding and the in vitroactivities of complex II (succinate dehydrogenase) and complex IV (cytochromeoxidase), suggesting that the stoichiometry of these components of theelectron transport chain is relatively constant across brain regions. Theability to assay complex I in vivo should provide a valuable tool toinvestigate the status of this mitochondrial enzyme in the living brain andsuggests potential imaging techniques for complex I in humans. [source] Detection of carbonyl-modified proteins in interfibrillar rat mitochondria using N, -aminooxymethylcarbonylhydrazino- D -biotin as an aldehyde/keto-reactive probe in combination with Western blot analysis and tandem mass spectrometryELECTROPHORESIS, Issue 6 2008Woon-Gye Chung Abstract There is now a large body of supporting data available that links oxidative modifications of proteins to a large number of diseases, degenerative disorders and aging. However, the detailed analysis of oxidative protein modifications remains challenging. Here, we report a new efficient method for identification of oxidatively modified proteins in complex biological samples which is based on the use of an aldehyde-reactive probe, N,-aminooxymethylcarbonylhydrazino- D -biotin (ARP), in combination with Western-type analyses and MS. The biotinylated hydroxylamine derivative forms a chemically stable oxime derivative with the aldehyde/keto group found in carbonyl-modified proteins. The biotin tag is detected by avidin affinity staining. ARP-positive proteins are subsequently subjected to in-gel trypsinization and MS/MS for protein identification. We demonstrate the usefulness of the method for the analysis of protein extracts obtained from interfibrillar heart mitochondria (IFM) from young and old rats. In this study, we identified as putative major protein targets of oxidative modifications the mitochondrial matrix protein, aconitase, the inner mitochondrial membrane protein, ADP/ATP translocase, and constituents of the electron transport chain complexes IV and V. An age-related increase of carbonyl levels was found for aconitase and ATP synthase. [source] | |||||||||||||