The Experts below are selected from a list of 189 Experts worldwide ranked by ideXlab platform
Nicola Elio Lofrumento - One of the best experts on this subject based on the ideXlab platform.
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Valinomycin induced energy-dependent mitochondrial swelling, cytochrome c release, cytosolic NADH/cytochrome c oxidation and apoptosis
Apoptosis, 2011Co-Authors: Dario Domenico Lofrumento, Gianluigi La Piana, Daniela Isabel Abbrescia, Valeria Palmitessa, Velia La Pesa, Domenico Marzulli, Nicola Elio LofrumentoAbstract:In Valinomycin induced stimulation of mitochondrial energy dependent reversible swelling, supported by succinate oxidation, cytochrome c (cyto- c ) and sulfite oxidase (Sox) [both present in the mitochondrial intermembrane space (MIS)] are released outside. This effect can be observed at a Valinomycin concentration as low as 1 nM. The rate of cytosolic NADH/cyto- c electron transport pathway is also greatly stimulated. The test on the permeability of mitochondrial outer membrane to exogenous cyto- c rules out the possibility that the increased rate of exogenous NADH oxidation could be ascribed either to extensively damaged or broken mitochondria. Accumulation of potassium inside the mitochondria, mediated by the highly specific ionophore Valinomycin, promotes an increase in the volume of matrix (evidenced by swelling) and the interaction points between the two mitochondrial membranes are expected to increase. The data reported and those previously published are consistent with the view that “respiratory contact sites” are involved in the transfer of reducing equivalents from cytosol to inside the mitochondria both in the absence and the presence of Valinomycin. Magnesium ions prevent at least in part the Valinomycin effects. Rather than to the dissipation of membrane potential, the pro-apoptotic property of Valinomycin can be ascribed to both the release of cyto- c from mitochondria to cytosol and the increased rate of cytosolic NADH coupled with an increased availability of energy in the form of glycolytic ATP, useful for the correct execution of apoptotic program.
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Valinomycin induced energy dependent mitochondrial swelling cytochrome c release cytosolic nadh cytochrome c oxidation and apoptosis
Apoptosis, 2011Co-Authors: Dario Domenico Lofrumento, Gianluigi La Piana, Daniela Isabel Abbrescia, Valeria Palmitessa, Velia La Pesa, Domenico Marzulli, Nicola Elio LofrumentoAbstract:In Valinomycin induced stimulation of mitochondrial energy dependent reversible swelling, supported by succinate oxidation, cytochrome c (cyto-c) and sulfite oxidase (Sox) [both present in the mitochondrial intermembrane space (MIS)] are released outside. This effect can be observed at a Valinomycin concentration as low as 1 nM. The rate of cytosolic NADH/cyto-c electron transport pathway is also greatly stimulated. The test on the permeability of mitochondrial outer membrane to exogenous cyto-c rules out the possibility that the increased rate of exogenous NADH oxidation could be ascribed either to extensively damaged or broken mitochondria. Accumulation of potassium inside the mitochondria, mediated by the highly specific ionophore Valinomycin, promotes an increase in the volume of matrix (evidenced by swelling) and the interaction points between the two mitochondrial membranes are expected to increase. The data reported and those previously published are consistent with the view that “respiratory contact sites” are involved in the transfer of reducing equivalents from cytosol to inside the mitochondria both in the absence and the presence of Valinomycin. Magnesium ions prevent at least in part the Valinomycin effects. Rather than to the dissipation of membrane potential, the pro-apoptotic property of Valinomycin can be ascribed to both the release of cyto-c from mitochondria to cytosol and the increased rate of cytosolic NADH coupled with an increased availability of energy in the form of glycolytic ATP, useful for the correct execution of apoptotic program.
Hiroshi Terada - One of the best experts on this subject based on the ideXlab platform.
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permeability transition independent release of mitochondrial cytochrome c induced by Valinomycin
FEBS Journal, 2002Co-Authors: Yasuo Shinohara, Mohamad Radwan Almofti, Takenori Yamamoto, Taro Ishida, Fumiyo Kita, Hideki Kanzaki, Masakatsu Ohnishi, Kikuji Yamashita, Shigeomi Shimizu, Hiroshi TeradaAbstract:To examine whether Valinomycin induces a mitochondrial permeability transition (PT), we investigated its effects on mitochondrial functions under various conditions. The acceleration of mitochondrial respiration and swelling, induced by Valinomycin, were found to be insensitive to inhibitors of the ordinary PT, indicating that Valinomycin does not induce the ordinary PT. Results of experiments using mitochondria isolated from transgenic mice expressing human bcl-2 also supported this conclusion. Furthermore, evidence for induction of PT pores by Valinomycin was not obtained by either electron microscopic analysis of mitochondrial configurations or by measurement of the permeability of the inner mitochondrial membrane by use of polyethylene glycol. However, Valinomycin did induce a significant release of cytochrome c, and thus it may be a nice tool to study the processes of mitochondrial cytochrome c release.
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Permeability transition‐independent release of mitochondrial cytochrome c induced by Valinomycin
European journal of biochemistry, 2002Co-Authors: Yasuo Shinohara, Mohamad Radwan Almofti, Takenori Yamamoto, Taro Ishida, Fumiyo Kita, Hideki Kanzaki, Masakatsu Ohnishi, Kikuji Yamashita, Shigeomi Shimizu, Hiroshi TeradaAbstract:To examine whether Valinomycin induces a mitochondrial permeability transition (PT), we investigated its effects on mitochondrial functions under various conditions. The acceleration of mitochondrial respiration and swelling, induced by Valinomycin, were found to be insensitive to inhibitors of the ordinary PT, indicating that Valinomycin does not induce the ordinary PT. Results of experiments using mitochondria isolated from transgenic mice expressing human bcl-2 also supported this conclusion. Furthermore, evidence for induction of PT pores by Valinomycin was not obtained by either electron microscopic analysis of mitochondrial configurations or by measurement of the permeability of the inner mitochondrial membrane by use of polyethylene glycol. However, Valinomycin did induce a significant release of cytochrome c, and thus it may be a nice tool to study the processes of mitochondrial cytochrome c release.
Dario Domenico Lofrumento - One of the best experts on this subject based on the ideXlab platform.
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Valinomycin induced energy-dependent mitochondrial swelling, cytochrome c release, cytosolic NADH/cytochrome c oxidation and apoptosis
Apoptosis, 2011Co-Authors: Dario Domenico Lofrumento, Gianluigi La Piana, Daniela Isabel Abbrescia, Valeria Palmitessa, Velia La Pesa, Domenico Marzulli, Nicola Elio LofrumentoAbstract:In Valinomycin induced stimulation of mitochondrial energy dependent reversible swelling, supported by succinate oxidation, cytochrome c (cyto- c ) and sulfite oxidase (Sox) [both present in the mitochondrial intermembrane space (MIS)] are released outside. This effect can be observed at a Valinomycin concentration as low as 1 nM. The rate of cytosolic NADH/cyto- c electron transport pathway is also greatly stimulated. The test on the permeability of mitochondrial outer membrane to exogenous cyto- c rules out the possibility that the increased rate of exogenous NADH oxidation could be ascribed either to extensively damaged or broken mitochondria. Accumulation of potassium inside the mitochondria, mediated by the highly specific ionophore Valinomycin, promotes an increase in the volume of matrix (evidenced by swelling) and the interaction points between the two mitochondrial membranes are expected to increase. The data reported and those previously published are consistent with the view that “respiratory contact sites” are involved in the transfer of reducing equivalents from cytosol to inside the mitochondria both in the absence and the presence of Valinomycin. Magnesium ions prevent at least in part the Valinomycin effects. Rather than to the dissipation of membrane potential, the pro-apoptotic property of Valinomycin can be ascribed to both the release of cyto- c from mitochondria to cytosol and the increased rate of cytosolic NADH coupled with an increased availability of energy in the form of glycolytic ATP, useful for the correct execution of apoptotic program.
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Valinomycin induced energy dependent mitochondrial swelling cytochrome c release cytosolic nadh cytochrome c oxidation and apoptosis
Apoptosis, 2011Co-Authors: Dario Domenico Lofrumento, Gianluigi La Piana, Daniela Isabel Abbrescia, Valeria Palmitessa, Velia La Pesa, Domenico Marzulli, Nicola Elio LofrumentoAbstract:In Valinomycin induced stimulation of mitochondrial energy dependent reversible swelling, supported by succinate oxidation, cytochrome c (cyto-c) and sulfite oxidase (Sox) [both present in the mitochondrial intermembrane space (MIS)] are released outside. This effect can be observed at a Valinomycin concentration as low as 1 nM. The rate of cytosolic NADH/cyto-c electron transport pathway is also greatly stimulated. The test on the permeability of mitochondrial outer membrane to exogenous cyto-c rules out the possibility that the increased rate of exogenous NADH oxidation could be ascribed either to extensively damaged or broken mitochondria. Accumulation of potassium inside the mitochondria, mediated by the highly specific ionophore Valinomycin, promotes an increase in the volume of matrix (evidenced by swelling) and the interaction points between the two mitochondrial membranes are expected to increase. The data reported and those previously published are consistent with the view that “respiratory contact sites” are involved in the transfer of reducing equivalents from cytosol to inside the mitochondria both in the absence and the presence of Valinomycin. Magnesium ions prevent at least in part the Valinomycin effects. Rather than to the dissipation of membrane potential, the pro-apoptotic property of Valinomycin can be ascribed to both the release of cyto-c from mitochondria to cytosol and the increased rate of cytosolic NADH coupled with an increased availability of energy in the form of glycolytic ATP, useful for the correct execution of apoptotic program.
Yasuo Shinohara - One of the best experts on this subject based on the ideXlab platform.
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permeability transition independent release of mitochondrial cytochrome c induced by Valinomycin
FEBS Journal, 2002Co-Authors: Yasuo Shinohara, Mohamad Radwan Almofti, Takenori Yamamoto, Taro Ishida, Fumiyo Kita, Hideki Kanzaki, Masakatsu Ohnishi, Kikuji Yamashita, Shigeomi Shimizu, Hiroshi TeradaAbstract:To examine whether Valinomycin induces a mitochondrial permeability transition (PT), we investigated its effects on mitochondrial functions under various conditions. The acceleration of mitochondrial respiration and swelling, induced by Valinomycin, were found to be insensitive to inhibitors of the ordinary PT, indicating that Valinomycin does not induce the ordinary PT. Results of experiments using mitochondria isolated from transgenic mice expressing human bcl-2 also supported this conclusion. Furthermore, evidence for induction of PT pores by Valinomycin was not obtained by either electron microscopic analysis of mitochondrial configurations or by measurement of the permeability of the inner mitochondrial membrane by use of polyethylene glycol. However, Valinomycin did induce a significant release of cytochrome c, and thus it may be a nice tool to study the processes of mitochondrial cytochrome c release.
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Permeability transition‐independent release of mitochondrial cytochrome c induced by Valinomycin
European journal of biochemistry, 2002Co-Authors: Yasuo Shinohara, Mohamad Radwan Almofti, Takenori Yamamoto, Taro Ishida, Fumiyo Kita, Hideki Kanzaki, Masakatsu Ohnishi, Kikuji Yamashita, Shigeomi Shimizu, Hiroshi TeradaAbstract:To examine whether Valinomycin induces a mitochondrial permeability transition (PT), we investigated its effects on mitochondrial functions under various conditions. The acceleration of mitochondrial respiration and swelling, induced by Valinomycin, were found to be insensitive to inhibitors of the ordinary PT, indicating that Valinomycin does not induce the ordinary PT. Results of experiments using mitochondria isolated from transgenic mice expressing human bcl-2 also supported this conclusion. Furthermore, evidence for induction of PT pores by Valinomycin was not obtained by either electron microscopic analysis of mitochondrial configurations or by measurement of the permeability of the inner mitochondrial membrane by use of polyethylene glycol. However, Valinomycin did induce a significant release of cytochrome c, and thus it may be a nice tool to study the processes of mitochondrial cytochrome c release.
Emanuel Makrlík - One of the best experts on this subject based on the ideXlab platform.
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Theoretical and experimental study of the complexation of Valinomycin with ammonium cation.
Biopolymers, 2008Co-Authors: Jiří Dybal, Sille Ehala, Václav Kašička, Emanuel MakrlíkAbstract:The interactions of Valinomycin, macrocyclic depsipeptide antibiotic ionophore, with ammonium cation NH4+ have been investigated. Using quantum mechanical density functional theory (DFT) calculations, the most probable structure of the Valinomycin-NH4+ complex species was predicted. In this complex, the ammonium cation is bound partly by three strong hydrogen bonds to three ester carbonyl oxygen atoms of Valinomycin and partly by somewhat weaker hydrogen bonds to the remaining three ester carbonyl groups of the Valinomycin ligand. The strength of the Valinomycin-NH4+ complex was evaluated experimentally by capillary affinity electrophoresis. From the dependence of Valinomycin effective electrophoretic mobility on the ammonium ion concentration in the background electrolyte, the apparent binding (association, stability) constant (Kb) of the Valinomycin-NH4+ complex in methanol was evaluated as log Kb = 1.52 ± 0.22. © 2008 Wiley Periodicals, Inc. Biopolymers 89: 1055–1060, 2008. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
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Determination of stability constants of Valinomycin complexes with ammonium and alkali metal ions by capillary affinity electrophoresis.
Electrophoresis, 2008Co-Authors: Sille Ehala, Václav Kašička, Emanuel MakrlíkAbstract:Capillary affinity electrophoresis (CAE) has been employed to investigate quantitatively the interactions of Valinomycin, macrocyclic depsipeptide antibiotic ionophore, with univalent cations, ammonium and alkali metal ions, K + , Cs + , Na + , and Li + , in methanol. The study involved measuring the change in effective electrophoretic mobility of Valinomycin while the cation concentrations in the BGE were increased. The corresponding apparent stability (binding) constants of the Valinomycin-univalent cation complexes were obtained from the dependence of Valinomycin effective mobility on the cation concentration in BGE using a nonlinear regression analysis. The calculated apparent stability constants of the above-mentioned complexes show the substantially higher selectivity of Valinomycin for K + and Cs + ions over Li + , Na + , and NH 4 + ions. CAE proved to be a suitable method for the investigation of both weak and strong interactions of Valinomycin with small ions.
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NMR evidence of a Valinomycin-proton complex.
Biopolymers, 2006Co-Authors: Jaroslav Kříž, Emanuel Makrlík, Petr VaňuraAbstract:In addition to the well-known complexes of Valinomycin with alkali metal cations, an equimolar complex of the same compound with proton was found to be formed in nitrobenzene. Hydrogen bis(1,2-dicarbollylide) cobaltate (HDCC) was used as a proton source. According to NMR spectra, the complex formation is quantitative at proton/Valinomycin molar ratios up to 1:1 but there is fast exchange of protons between coordinated and uncoordinated Valinomycin molecules at lower ratios. 1H and 13C NMR spectra show a dramatic change in the Valinomycin conformation during its coordination with protons, probably from a propeller-like to a bracelet-like form. As Valinomycin is one of the well-known ion-carrying ionophores facilitating especially the K+ ion transport across a biological membrane, the existence of the Valinomycin-proton complex could be important in biochemistry and biology. © 2005 Wiley Periodicals, Inc. Biopolymers 81: 104–109, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
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Stability of protonated Valinomycin in water saturated nitrobenzene
Journal of Radioanalytical and Nuclear Chemistry, 2006Co-Authors: Emanuel Makrlík, Petr VaňuraAbstract:From the extraction experiments and g-activity measurements, the extraction constant of the equilibrium H+(aq)+NaL+(nb)UHL+(nb)+Na+(aq) taking place in the two-phase water-nitrobenzene system (L = Valinomycin; aq = aqueous phase, nb = nitrobenzene phase) was evaluated as log Kex(H+,NaL+) = -1.1±0.1. Further, the stability constant of the Valinomycin-proton complex in nitrobenzene saturated water was calculated: log bnb(HL+) = 5.3±0.1. Finally, the stability constants of complexes of some univalent cations with Valinomycin were summarized and discussed.
