Difference between revisions of "Gnaiger 2002 Biochem Soc Trans"
| Line 5: | Line 5: | ||
|journal=Biochem. Soc. Trans. | |journal=Biochem. Soc. Trans. | ||
|mipnetlab=AT_Innsbruck_GnaigerE | |mipnetlab=AT_Innsbruck_GnaigerE | ||
|abstract=In the intracellular microenvironment of active muscle tissue, high rates of respiration are maintained at near-limiting oxygen concentrations. The respiration of isolated heart mitochondria is a hyperbolic function of oxygen concentration and half-maximal rates were obtained at 0.4 and 0.7 | |abstract=In the intracellular microenvironment of active muscle tissue, high rates of respiration are maintained at near-limiting oxygen concentrations. The respiration of isolated heart mitochondria is a hyperbolic function of oxygen concentration and half-maximal rates were obtained at 0.4 and 0.7 µM O2 with substrates for the respiratory chain (succinate) and cytochrome c oxidase [N,N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride (TMPD)ascorbate] respectively at 30 °C and with maximum ADP stimulation (State 3). The respiratory response of cytochrome c-depleted mitoplasts to external cytochrome | ||
c was biphasic with TMPD, but showed a monophasic hyperbolic function with succinate. Half-maximal stimulation of respiration was obtained at 0.4 | c was biphasic with TMPD, but showed a monophasic hyperbolic function with succinate. Half-maximal stimulation of respiration was obtained at 0.4 µM cytochrome c, which was nearly identical to the high-affinity K'm for cytochrome c of cytochrome c oxidase supplied with TMPD. The capacity of cytochrome c oxidase in the presence of TMPD was 2-fold higher than the | ||
capacity of the respiratory chain with succinate, measured at environmental normoxic levels. This apparent excess capacity, however, is significantly decreased under physiological intracellular oxygen conditions and declines steeply under hypoxic conditions. Similarly, the excess capacity of cytochrome c oxidase declines with progressive cytochrome c depletion. The flux control coeficient of cytochrome c oxidase, therefore, increases as a function of substrate limitation of oxygen and cytochrome c, which suggests a direct | capacity of the respiratory chain with succinate, measured at environmental normoxic levels. This apparent excess capacity, however, is significantly decreased under physiological intracellular oxygen conditions and declines steeply under hypoxic conditions. Similarly, the excess capacity of cytochrome c oxidase declines with progressive cytochrome c depletion. The flux control coeficient of cytochrome c oxidase, therefore, increases as a function of substrate limitation of oxygen and cytochrome c, which suggests a direct | ||
functional role for the apparent excess capacity of cytochrome c oxidase in hypoxia and under conditions of intracellular accumulation of cytochrome | functional role for the apparent excess capacity of cytochrome c oxidase in hypoxia and under conditions of intracellular accumulation of cytochrome | ||
Revision as of 16:10, 13 September 2010
| Gnaiger E, Kuznetsov AV (2002) Mitochondrial respiration at low levels of oxygen and cytochrome c. Biochem. Soc. Trans. 30: 242-248. |
Gnaiger E, Kuznetsov AV (2002) Biochem. Soc. Trans.
Abstract: In the intracellular microenvironment of active muscle tissue, high rates of respiration are maintained at near-limiting oxygen concentrations. The respiration of isolated heart mitochondria is a hyperbolic function of oxygen concentration and half-maximal rates were obtained at 0.4 and 0.7 µM O2 with substrates for the respiratory chain (succinate) and cytochrome c oxidase [N,N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride (TMPD)ascorbate] respectively at 30 °C and with maximum ADP stimulation (State 3). The respiratory response of cytochrome c-depleted mitoplasts to external cytochrome c was biphasic with TMPD, but showed a monophasic hyperbolic function with succinate. Half-maximal stimulation of respiration was obtained at 0.4 µM cytochrome c, which was nearly identical to the high-affinity K'm for cytochrome c of cytochrome c oxidase supplied with TMPD. The capacity of cytochrome c oxidase in the presence of TMPD was 2-fold higher than the capacity of the respiratory chain with succinate, measured at environmental normoxic levels. This apparent excess capacity, however, is significantly decreased under physiological intracellular oxygen conditions and declines steeply under hypoxic conditions. Similarly, the excess capacity of cytochrome c oxidase declines with progressive cytochrome c depletion. The flux control coeficient of cytochrome c oxidase, therefore, increases as a function of substrate limitation of oxygen and cytochrome c, which suggests a direct functional role for the apparent excess capacity of cytochrome c oxidase in hypoxia and under conditions of intracellular accumulation of cytochrome c after its release from mitochondria. • Keywords: Cytochrome c kinetics, Heart mitochondria, Highresolution respirometry, Metabolic flux control analysis, Oxygen kinetics
• O2k-Network Lab: AT_Innsbruck_GnaigerE
Labels:
Stress:Hypoxia Organism: Rat Tissue;cell: Cardiac Muscle"Cardiac Muscle" is not in the list (Heart, Skeletal muscle, Nervous system, Liver, Kidney, Lung;gill, Islet cell;pancreas;thymus, Endothelial;epithelial;mesothelial cell, Blood cells, Fat, ...) of allowed values for the "Tissue and cell" property. Preparation: Isolated Mitochondria"Isolated Mitochondria" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Oxidase; Biochemical Oxidation"Oxidase; Biochemical Oxidation" is not in the list (Intact organism, Intact organ, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria, SMP, Chloroplasts, Enzyme, Oxidase;biochemical oxidation, ...) of allowed values for the "Preparation" property., Enzyme
Regulation: Respiration; OXPHOS; ETS Capacity"Respiration; OXPHOS; ETS Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Flux Control; Additivity; Threshold; Excess Capacity"Flux Control; Additivity; Threshold; Excess Capacity" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property., Coupling; Membrane Potential"Coupling; Membrane Potential" is not in the list (Aerobic glycolysis, ADP, ATP, ATP production, AMP, Calcium, Coupling efficiency;uncoupling, Cyt c, Flux control, Inhibitor, ...) of allowed values for the "Respiration and regulation" property.
HRR: Oxygraph-2k
