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Wieslawa Jarmuszkiewicz - One of the best experts on this subject based on the ideXlab platform.
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uncoupling protein 1 inhibition by purine nucleotides is under the control of the endogenous ubiquinone Redox State
Biochemical Journal, 2009Co-Authors: Aleksandra Swidabarteczka, Andrzej Woydaploszczyca, Francis Sluse, Wieslawa JarmuszkiewiczAbstract:We studied non-esterified fatty acid-induced uncoupling of heterologously expressed rat UCP1 (uncoupling protein 1) in yeast mitochondria, as well as UCP1 in rat BAT (brown adipose tissue) mitochondria. The proton-conductance curves and the relationship between the ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between the ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of the membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone Redox State. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone Redox State was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidizing pathways, indicate that the endogenous ubiquinone Redox State has no effect on non-esterified fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone Redox State-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85–88%.
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Uncoupling protein 1 inhibition by purine nucleotides is under control of the endogenous ubiquinone Redox State
Biochemical Journal, 2009Co-Authors: Aleksandra Swida-barteczka, Francis Sluse, Andrzej Woyda-ploszczyca, Wieslawa JarmuszkiewiczAbstract:We studied free fatty acid-induced uncoupling of heterologously expressed rat UCP1 in yeast mitochondria as well as UCP1 in rat BAT mitochondria. The proton conductance curves and the relationship between ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone Redox State. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone Redox State was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidising pathways, indicate that the endogenous ubiquinone Redox State has no effect on free fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone Redox State-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85-88%.
Francis Sluse - One of the best experts on this subject based on the ideXlab platform.
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uncoupling protein 1 inhibition by purine nucleotides is under the control of the endogenous ubiquinone Redox State
Biochemical Journal, 2009Co-Authors: Aleksandra Swidabarteczka, Andrzej Woydaploszczyca, Francis Sluse, Wieslawa JarmuszkiewiczAbstract:We studied non-esterified fatty acid-induced uncoupling of heterologously expressed rat UCP1 (uncoupling protein 1) in yeast mitochondria, as well as UCP1 in rat BAT (brown adipose tissue) mitochondria. The proton-conductance curves and the relationship between the ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between the ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of the membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone Redox State. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone Redox State was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidizing pathways, indicate that the endogenous ubiquinone Redox State has no effect on non-esterified fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone Redox State-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85–88%.
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Uncoupling protein 1 inhibition by purine nucleotides is under control of the endogenous ubiquinone Redox State
Biochemical Journal, 2009Co-Authors: Aleksandra Swida-barteczka, Francis Sluse, Andrzej Woyda-ploszczyca, Wieslawa JarmuszkiewiczAbstract:We studied free fatty acid-induced uncoupling of heterologously expressed rat UCP1 in yeast mitochondria as well as UCP1 in rat BAT mitochondria. The proton conductance curves and the relationship between ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone Redox State. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone Redox State was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidising pathways, indicate that the endogenous ubiquinone Redox State has no effect on free fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone Redox State-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85-88%.
M Teixeira J De Mattos - One of the best experts on this subject based on the ideXlab platform.
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the steady State internal Redox State nadh nad reflects the external Redox State and is correlated with catabolic adaptation in escherichia coli
Journal of Bacteriology, 1999Co-Authors: M.r. De Graef, Svetlana Alexeeva, Jacky L Snoep, M Teixeira J De MattosAbstract:Escherichia coli MC4100 was grown in anaerobic glucose-limited chemostat cultures, either in the presence of an electron acceptor (fumarate, nitrate, or oxygen) or fully fermentatively. The steady-State NADH/NAD ratio depended on the nature of the electron acceptor. Anaerobically, the ratio was highest, and it decreased progressively with increasing midpoint potential of the electron acceptor. Similarly, decreasing the dissolved oxygen tension resulted in an increased NADH/NAD ratio. As pyruvate catabolism is a major switch point between fermentative and respiratory behavior, the fluxes through the different pyruvate-consuming enzymes were calculated. Although pyruvate formate lyase (PFL) is inactivated by oxygen, it was inferred that the in vivo activity of the enzyme occurred at low dissolved oxygen tensions (DOT ≤ 1%). A simultaneous flux from pyruvate through both PFL and the pyruvate dehydrogenase complex (PDHc) was observed. In anaerobic cultures with fumarate or nitrate as an electron acceptor, a significant flux through the PDHc was calculated on the basis of the Redox balance, the measured products, and the known biochemistry. This result calls into question the common assumption that the complex cannot be active under these conditions. In vitro activity measurements of PDHc showed that the cellular content of the enzyme varied with the internal Redox State and revealed an activity for dissolved oxygen tension of below 1%. Whereas Western blots showed that the E3 subunit of PDHc (dihydrolipoamide dehydrogenase) did not vary to a large extent under the conditions tested, the E2 subunit (dihydrolipoamide acetyltransferase) amount followed the trend that was found for the in vitro PDHc activity. From this it is concluded that regulation of the PDHc is exerted at the E1/E2 operon (aceEF). We propose that the external Redox State (measured as the midpoint potentials of those terminal acceptors with which the cell has sufficient capacity to react) is reflected by the internal Redox State. The latter may subsequently govern both the expression and the activity of the two pyruvate-catabolizing enzymes.
M.r. De Graef - One of the best experts on this subject based on the ideXlab platform.
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The Steady-State Internal Redox State (NADH/NAD) Reflects the External Redox State and Is Correlated with Catabolic Adaptation in Escherichia coli
Journal of Bacteriology, 1999Co-Authors: M.r. De Graef, Svetlana Alexeeva, Jacky L Snoep, M. J. Teixeira De MattosAbstract:Escherichia coli MC4100 was grown in anaerobic glucose-limited chemostat cultures, either in the presence of an electron acceptor (fumarate, nitrate, or oxygen) or fully fermentatively. The steady-State NADH/NAD ratio depended on the nature of the electron acceptor. Anaerobically, the ratio was highest, and it decreased progressively with increasing midpoint potential of the electron acceptor. Similarly, decreasing the dissolved oxygen tension resulted in an increased NADH/NAD ratio. As pyruvate catabolism is a major switch point between fermentative and respiratory behavior, the fluxes through the different pyruvate-consuming enzymes were calculated. Although pyruvate formate lyase (PFL) is inactivated by oxygen, it was inferred that the in vivo activity of the enzyme occurred at low dissolved oxygen tensions (DOT ≤ 1%). A simultaneous flux from pyruvate through both PFL and the pyruvate dehydrogenase complex (PDHc) was observed. In anaerobic cultures with fumarate or nitrate as an electron acceptor, a significant flux through the PDHc was calculated on the basis of the Redox balance, the measured products, and the known biochemistry. This result calls into question the common assumption that the complex cannot be active under these conditions. In vitro activity measurements of PDHc showed that the cellular content of the enzyme varied with the internal Redox State and revealed an activity for dissolved oxygen tension of below 1%. Whereas Western blots showed that the E3 subunit of PDHc (dihydrolipoamide dehydrogenase) did not vary to a large extent under the conditions tested, the E2 subunit (dihydrolipoamide acetyltransferase) amount followed the trend that was found for the in vitro PDHc activity. From this it is concluded that regulation of the PDHc is exerted at the E1/E2 operon (aceEF). We propose that the external Redox State (measured as the midpoint potentials of those terminal acceptors with which the cell has sufficient capacity to react) is reflected by the internal Redox State. The latter may subsequently govern both the expression and the activity of the two pyruvate-catabolizing enzymes.
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the steady State internal Redox State nadh nad reflects the external Redox State and is correlated with catabolic adaptation in escherichia coli
Journal of Bacteriology, 1999Co-Authors: M.r. De Graef, Svetlana Alexeeva, Jacky L Snoep, M Teixeira J De MattosAbstract:Escherichia coli MC4100 was grown in anaerobic glucose-limited chemostat cultures, either in the presence of an electron acceptor (fumarate, nitrate, or oxygen) or fully fermentatively. The steady-State NADH/NAD ratio depended on the nature of the electron acceptor. Anaerobically, the ratio was highest, and it decreased progressively with increasing midpoint potential of the electron acceptor. Similarly, decreasing the dissolved oxygen tension resulted in an increased NADH/NAD ratio. As pyruvate catabolism is a major switch point between fermentative and respiratory behavior, the fluxes through the different pyruvate-consuming enzymes were calculated. Although pyruvate formate lyase (PFL) is inactivated by oxygen, it was inferred that the in vivo activity of the enzyme occurred at low dissolved oxygen tensions (DOT ≤ 1%). A simultaneous flux from pyruvate through both PFL and the pyruvate dehydrogenase complex (PDHc) was observed. In anaerobic cultures with fumarate or nitrate as an electron acceptor, a significant flux through the PDHc was calculated on the basis of the Redox balance, the measured products, and the known biochemistry. This result calls into question the common assumption that the complex cannot be active under these conditions. In vitro activity measurements of PDHc showed that the cellular content of the enzyme varied with the internal Redox State and revealed an activity for dissolved oxygen tension of below 1%. Whereas Western blots showed that the E3 subunit of PDHc (dihydrolipoamide dehydrogenase) did not vary to a large extent under the conditions tested, the E2 subunit (dihydrolipoamide acetyltransferase) amount followed the trend that was found for the in vitro PDHc activity. From this it is concluded that regulation of the PDHc is exerted at the E1/E2 operon (aceEF). We propose that the external Redox State (measured as the midpoint potentials of those terminal acceptors with which the cell has sufficient capacity to react) is reflected by the internal Redox State. The latter may subsequently govern both the expression and the activity of the two pyruvate-catabolizing enzymes.
Aleksandra Swidabarteczka - One of the best experts on this subject based on the ideXlab platform.
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uncoupling protein 1 inhibition by purine nucleotides is under the control of the endogenous ubiquinone Redox State
Biochemical Journal, 2009Co-Authors: Aleksandra Swidabarteczka, Andrzej Woydaploszczyca, Francis Sluse, Wieslawa JarmuszkiewiczAbstract:We studied non-esterified fatty acid-induced uncoupling of heterologously expressed rat UCP1 (uncoupling protein 1) in yeast mitochondria, as well as UCP1 in rat BAT (brown adipose tissue) mitochondria. The proton-conductance curves and the relationship between the ubiquinone reduction level and membrane potential were determined in non-phosphorylating BAT and yeast mitochondria. The ADP/O method was applied to determine the ADP phosphorylation rate and the relationship between the ubiquinone reduction level and respiration rate in yeast mitochondria. Our studies of the membranous ubiquinone reduction level in mitochondria demonstrate that activation of UCP1 leads to a purine nucleotide-sensitive decrease in the ubiquinone Redox State. Results obtained for non-phosphorylating and phosphorylating mitochondria, as the endogenous ubiquinone Redox State was gradually varied by a lowering rate of the ubiquinone-reducing or ubiquinol-oxidizing pathways, indicate that the endogenous ubiquinone Redox State has no effect on non-esterified fatty acid-induced UCP1 activity in the absence of GTP, and can only regulate this activity through sensitivity to inhibition by the purine nucleotide. At a given oleic acid concentration, inhibition by GTP diminishes when ubiquinone is reduced sufficiently. The ubiquinone Redox State-dependent alleviation of UCP1 inhibition by the purine nucleotide was observed at a high ubiquinone reduction level, when it exceeded 85–88%.
