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Complex V (complex + v)
Selected AbstractsChemInform Abstract: ,,,-Unsaturated Fischer Carbene Complexes vs.CHEMINFORM, Issue 2 20013-Dipoles: Reactions with Nitrones, Nitrilimines. Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [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] Sevoflurane and propofol depolarize mitochondria in rat and human cerebrocortical synaptosomes by different mechanismsACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009R. BAINS Background and objectives: The mitochondrial membrane potential drives the main functions of the mitochondria. Sevoflurane depolarizes neural mitochondria. There is still, however, limited information concerning the effect of anaesthetics on neural mitochondria in humans. The effect of sevoflurane and propofol on the intracellular Ca2+ concentration [Ca2+]i and the mitochondrial membrane potential (,,m) was therefore compared in rat and human synaptosomes, and the changes were related to interventions in the electron transport chain. Methods: Synaptosomes from rat and human cerebral cortex were loaded with the fluorescent probes fura-2 ([Ca2+]i) and JC-1 (,,m) before exposure to sevoflurane 1 and 2 minimum alveolar concentration (MAC), and propofol 30 and 100 ,M. The effect on the electron transport chain was investigated by blocking complex V. Results: Sevoflurane and propofol decreased ,,m in rat synaptosomes in a dose-dependent manner, and to the same extent by equipotent doses. Inhibition of complex V enhanced the depolarizing effect of sevoflurane 2 MAC, but not of propofol 100 ,M. Neither sevoflurane nor propofol affected [Ca2+]i significantly. Sevoflurane and propofol decreased ,,m in human synaptosomes to the same extent as in the rat experiments. Conclusions: Sevoflurane and propofol at equipotent doses depolarize the mitochondria in rat and human nerve terminals to the same extent. The depolarizing effect of propofol on ,m was more rapid in onset than that of sevoflurane. Whereas sevoflurane inhibits the respiratory chain sufficiently to cause ATP synthase reversal, the depolarizing effect of propofol seems to be related to inhibition of the respiratory chain from complex I to V. [source] Perturbation of mitochondrial complex V alters the response to dietary restriction in DrosophilaAGING CELL, Issue 1 2010Sepehr Bahadorani Summary Studies in a broad spectrum of model organisms have reported that dietary restriction (DR) is associated with an increase in mitochondrial electron transport chain (ETC) function. However, the question of whether ETC function is required for DR-mediated longevity remains controversial. Here, we report that genetic and pharmacological interventions that target mitochondrial complex V affect Drosophila lifespan in a nutrient-dependent manner. These findings support a requirement for mitochondrial complex V in DR-mediated longevity in flies. [source] Isoflurane-induced depolarization of neural mitochondria increases with ageACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 1 2009RAVI BAINS Background and objectives: The mitochondrial membrane potential (,,m) drives the three fundamental functions of mitochondria, namely adenosine triphosphate (ATP) generation, Ca2+ uptake/storage, and generation/detoxification of ROS. Isoflurane depolarizes neural mitochondria. The sensitivity for general anesthetics increases with age, but the mechanism for this age-related sensitivity is still unknown. We compared the effect of isoflurane on [Ca2+]i and ,,m in isolated pre-synaptic terminals (synaptosomes) from neonatal, adolescent, and adult rats and the influence of interventions in the respiratory chain was assessed. Methods: Synaptosomes were loaded with the fluorescent probes fura-2 ([Ca2+]i) and JC-1 (,,m) and exposed to isoflurane 1 and 2 minimum alveolar concentration (MAC). The effect on the electron transport chain was investigated by blocking complexes I and V. Results: In neonatal rats isoflurane had no significant effect on ,,m. In adolescent and adult synaptosomes, however, isoflurane 1 and 2 MAC decreased ,,m. Isoflurane 2 MAC increased [Ca2+]i in neonatal and adolescent rats, but not in adult synaptosomes. In Ca2+ -depleted medium, isoflurane still decreased ,,m, while [Ca2+]i remained unaltered. By blocking complex V of the respiratory chain, the isoflurane-induced mitochondrial depolarization was enhanced in all age groups. Blocking complex I depolarized the mitochondria to the same extent as isoflurane 2 MAC, but without any additive effect. Conclusions: The depolarizing effect of isoflurane on neural mitochondria is more pronounced in the adolescent and adult than in neonatal synaptosomes. The increased mitochondrial sensitivity with age seems to be related to the reversed function of the ATP synthase of the electron transport chain. [source] Volatile anaesthetics depolarize neural mitochondria by inhibiton of the electron transport chainACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 5 2006R. Bains Background:, The mitochondrial membrane potential (,,m) controls the generation of adenosine triphosphate (ATP) and reactive oxygen species, and sequesteration of intracellular Ca2+[Ca2+]i. Clinical concentrations of sevoflurane affect the ,,m in neural mitochondria, but the mechanisms remain elusive. The aim of the present study was to compare the effect of isoflurane and sevoflurane on ,,m in rat pre-synaptic terminals (synaptosomes), and to investigate whether these agents affect ,,m by inhibiting the respiratory chain. Methods:, Synaptosomes were loaded with the fluorescent probes JC-1 (,,m) and Fura-2 ([Ca2+]i) and exposed to isoflurane or sevoflurane. The effect of the anaesthetics on the electron transport chain was investigated by blocking complex I and complex V. Results:, Isoflurane 1 and 2 minimum alveolar concentration (MAC) decreased the normalized JC-1 ratio from 0.92 ± 0.03 in control to 0.86 ± 0.02 and 0.81 ± 0.01, respectively, reflecting a depolarization of the mitochondrial membrane (n = 9). Isoflurane 2 MAC increased [Ca2+]i. In Ca2+ -depleted medium, isoflurane still decreased ,,m while [Ca2+]i remained unaltered. The effect of isoflurane was more pronounced than for sevoflurane. Blocking complex V of the respiratory chain enhanced the isoflurane- and sevoflurane-induced mitochondrial depolarization, whereas blocking complex I and V decreased ,,m to the same extent in control, isoflurane and sevoflurane experiments. Conclusions:, Isoflurane and sevoflurane may act as metabolic inhibitors by depolarizing pre-synaptic mitochondria through inhibition of the electron transport chain, although isoflurane seems to inhibit mitochondrial function more significantly than sevoflurane. Both agents inhibit the respiratory chain sufficiently to cause ATP synthase reversal. [source] Influence of supported vanadium catalyst on ethylene polymerization reactionsPOLYMER INTERNATIONAL, Issue 2 2008Sutapa Ghosh Abstract BACKGROUND: In the research area of homogeneous Ziegler,Natta olefin polymerization, classic vanadium catalyst systems have shown a number of favourable performances. These catalysts are useful for (i) the preparation of high molecular weight polymers with narrow molecular weight distributions, (ii) the preparation of ethylene/R -olefin copolymers with high R -olefin incorporation and (iii) the preparation of syndiotactic polypropylenes. In view of the above merits of vanadium-based catalysts for polymerization reactions, the development of well-defined single-site vanadium catalysts for polymerization reactions is presently an extremely important industrial goal. The main aim of this work was the synthesis and characterization of a heterogeneous low-coordinate non-metallocene (phenyl)imido vanadium catalyst, V(NAr)Cl3, and its utility for ethylene polymerization. RESULTS: Imido vanadium complex V(NAr)Cl3 was synthesized and immobilized onto a series of inorganic supports: SiO2, methylaluminoxane (MAO)-modified SiO2 (4.5 and 23 wt% Al/SiO2), SiO2 Al2O3, MgCl2, MCM-41 and MgO. Metal contents on the supported catalysts determined by X-ray fluorescence spectroscopy remained between 0.050 and 0.100 mmol V g,1 support. Thermal stability of the catalysts was determined by differential scanning calorimetry (DSC). Characterization of polyethylene was done by gel permeation chromatography and DSC. All catalyst systems were found to be active in ethylene polymerization in the presence of MAO or triisobutylaluminium/MAO mixture (Al/V = 1000). Catalyst activity was found to depend on the support nature, being between 7.5 and 80.0 kg PE (mol V),1 h,1. Finally, all catalyst systems were found to be reusable for up to three cycles. CONCLUSION: Best results were observed in the case of silica as support. Acid or basic supports afforded less active systems. In situ immobilization led to higher catalyst activity. The resulting polyethylenes in all experiments had ultrahigh molecular weight. Finally, this work explains the synthesis and characterization of reusable supported novel vanadium catalysts, which are useful in the synthesis of very high molecular weight ethylene polymers. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||