Mitochondrial cytochrome c oxidase and control of energy metabolism: measurements in suspensions of isolated mitochondria

2014 ◽  
Vol 117 (12) ◽  
pp. 1424-1430 ◽  
Author(s):  
David F. Wilson ◽  
David K. Harrison ◽  
Andrei Vinogradov
Keyword(s):  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Respiratory Rate ◽  
Cytochrome C Oxidase ◽  
Energy State ◽  
Atp Synthesis ◽  
Oxygen Depletion ◽  
High Energy

Cytochrome c oxidase is the enzyme responsible for oxygen consumption by mitochondrial oxidative phosphorylation and coupling site 3 of oxidative phosphorylation. In this role it determines the cellular rate of ATP synthesis by oxidative phosphorylation and is the key to understanding how energy metabolism is regulated. Four electrons are required for the reduction of oxygen to water, and these are provided by the one-electron donor, cytochrome c. The rate of oxygen consumption (ATP synthesis) is dependent on the fraction of cytochrome c reduced (fred), oxygen pressure (pO2), energy state ([ATP]/[ADP][Pi]), and pH. In coupled mitochondria (high energy state) and pO2 >60 torr, the rate increases in an exponential-like fashion with increasing fred. When the dependence on fred is fitted to the equation rate = a(fred)b, a decreased from 100 to near 20, and b increased from 1.3 to 4 as the pH of the medium increased from 6.5 to 8.3. During oxygen depletion from the medium fred progressively increases and the rate of respiration decreases. The respiratory rate falls to ½ (P50) by about 1.5 torr, at which point fred is substantially increased. The metabolically relevant dependence on pO2 is obtained by correcting for the increase in fred, in which case the P50 is 12 torr. Adding an uncoupler of oxidative phosphorylation eliminates the dependence of the cytochrome c oxidase activity on pH and energy state. The respiratory rate becomes proportional to fred and the P50 decreases to less than 1 torr.

Sulphide oxidation and oxidative phosphorylation in the mitochondria of the lugworm

1997 ◽  
Vol 200 (1) ◽  
pp. 83-92 ◽  
Author(s):  
S Vökel ◽  
M K Grieshaber
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Electron Flow ◽  
Respiratory Control ◽  
Sulphide Oxidation ◽  
Atp Production ◽  
Sulphide Concentration ◽  
Flow Through

Oxygen consumption, ATP production and cytochrome c oxidase activity of isolated mitochondria from body-wall tissue of Arenicola marina were measured as a function of sulphide concentration, and the effect of inhibitors of the respiratory complexes on these processes was determined. Concentrations of sulphide between 6 and 9 µmol l-1 induced oxygen consumption with a respiratory control ratio of 1.7. Production of ATP was stimulated by the addition of sulphide, reaching a maximal value of 67 nmol min-1 mg-1 protein at a sulphide concentration of 8 µmol l-1. Under these conditions, 1 mole of ATP was formed per mole of sulphide consumed. Higher concentrations of sulphide led to a decrease in ATP production until complete inhibition occurred at approximately 50 µmol l-1. The production of ATP with malate and succinate was stimulated by approximately 15 % in the presence of 4 µmol l-1 sulphide, but decreased at sulphide concentrations higher than 15­20 µmol l-1. Cytochrome c oxidase was also inhibited by sulphide, showing half-maximal inhibition at 1.5 µmol l-1 sulphide. Sulphide-induced ATP production was inhibited by antimycin, cyanide and oligomycin but not by rotenone or salicylhydroxamic acid. The present data indicate that sulphide oxidation is coupled to oxidative phosphorylation solely by electron flow through cytochrome c oxidase, whereas the alternative oxidase does not serve as a coupling site. At sulphide concentrations higher than 20 µmol l-1, oxidation of sulphide serves mainly as a detoxification process rather than as a source of energy.

scholarly journals Control by cytochrome c oxidase of the cellular oxidative phosphorylation system depends on the mitochondrial energy state

2006 ◽  
Vol 396 (3) ◽  
pp. 573-583 ◽  
Author(s):  
Claudia Piccoli ◽  
Rosella Scrima ◽  
Domenico Boffoli ◽  
Nazzareno Capitanio
Keyword(s):  
Cytochrome C ◽  
Oxidative Phosphorylation ◽  
Cytochrome C Oxidase ◽  
Energy State ◽  
Exercise Intolerance ◽  
Regulatory Function ◽  
Control Analysis ◽  
Intact Cells ◽  
Flux Control ◽  
The Impact

Recent measurements of the flux control exerted by cytochrome c oxidase on the respiratory activity in intact cells have led to a re-appraisal of its regulatory function. We have further extended this in vivo study in the framework of the Metabolic Control Analysis and evaluated the impact of the mitochondrial transmembrane electrochemical potential (ΔμH+) on the control strength of the oxidase. The results indicate that, under conditions mimicking the mitochondrial State 4 of respiration, both the flux control coefficient and the threshold value of cytochrome oxidase are modified with respect to the uncoupled condition. The results obtained are consistent with a model based on changes in the assembly state of the oxidative phosphorylation enzyme complexes and possible implications in the understanding of exercise-intolerance of human neuromuscular degenerative diseases are discussed.

Cellular energy utilization and molecular origin of standard metabolic rate in mammals

1997 ◽  
Vol 77 (3) ◽  
pp. 731-758 ◽  
Author(s):  
D. F. Rolfe ◽  
G. C. Brown
Keyword(s):  
Free Energy ◽  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Oxidative Phosphorylation ◽  
Metabolic Rate ◽  
Atp Synthesis ◽  
Standard Metabolic Rate ◽  
Evolutionary Significance ◽  
Proton Leak ◽  
Molecular Origin

The molecular origin of standard metabolic rate and thermogenesis in mammals is examined. It is pointed out that there are important differences and distinctions between the cellular reactions that 1) couple to oxygen consumption, 2) uncouple metabolism, 3) hydrolyze ATP, 4) control metabolic rate, 5) regulate metabolic rate, 6) produce heat, and 7) dissipate free energy. The quantitative contribution of different cellular reactions to these processes is assessed in mammals. We estimate that approximately 90% of mammalian oxygen consumption in the standard state is mitochondrial, of which approximately 20% is uncoupled by the mitochondrial proton leak and 80% is coupled to ATP synthesis. The consequences of the significant contribution of proton leak to standard metabolic rate for tissue P-to-O ratio, heat production, and free energy dissipation by oxidative phosphorylation and the estimated contribution of ATP-consuming processes to tissue oxygen consumption rate are discussed. Of the 80% of oxygen consumption coupled to ATP synthesis, approximately 25-30% is used by protein synthesis, 19-28% by the Na(+)-K(+)-ATPase, 4-8% by the Ca2(+)-ATPase, 2-8% by the actinomyosin ATPase, 7-10% by gluconeogenesis, and 3% by ureagenesis, with mRNA synthesis and substrate cycling also making significant contributions. The main cellular reactions that uncouple standard energy metabolism are the Na+, K+, H+, and Ca2+ channels and leaks of cell membranes and protein breakdown. Cellular metabolic rate is controlled by a number of processes including metabolic demand and substrate supply. The differences in standard metabolic rate between animals of different body mass and phylogeny appear to be due to proportionate changes in the whole of energy metabolism. Heat is produced by some reactions and taken up by others but is mainly produced by the reactions of mitochondrial respiration, oxidative phosphorylation, and proton leak on the inner mitochondrial membrane. Free energy is dissipated by all cellular reactions, but the major contributions are by the ATP-utilizing reactions and the uncoupling reactions. The functions and evolutionary significance of standard metabolic rate are discussed.

ConA induced changes in energy metabolism of rat thymocytes

1992 ◽  
Vol 12 (5) ◽  
pp. 381-386 ◽  
Author(s):  
F. Buttgereit ◽  
M. D. Brand ◽  
M. Müller
Keyword(s):  
Protein Synthesis ◽  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Dna Synthesis ◽  
Atp Synthesis ◽  
Proton Leak ◽  
Ehrlich Ascites ◽  
Activated State ◽  
Ehrlich Ascites Tumour ◽  
Induced Changes

The influence of ConA on the energy metabolism of quiescent rat thymocytes was investigated by measuring the effects of inhibitors of protein synthesis, proteolysis, RNA/DNA synthesis, Na+K+-ATPase, Ca2+-ATPase and mitochondrial ATP synthesis on respiration. Only about 50% of the coupled oxygen consumption of quiescent thymocytes could be assigned to specific processes using two different media. Under these conditions the oxygen is mainly used to drive mitochondrial proton leak and to provide ATP for protein synthesis and cation transport, whereas oxygen consumption to provide ATP for RNA/DNA synthesis and ATP-dependent proteolysis was not measurable. The mitogen ConA produced a persistent increase in oxygen consumption by about 30% within seconds. After stimulation more than 80% of respiration could be assigned to specific processes. The major oxygen consuming processes of ConA-stimulated thymocytes are mitochondrial proton leak, protein synthesis and Na+K+-ATPase with about 20% each of total oxygen consumption, while Ca2+-ATPase and RNA/DNA synthesis contribute about 10% each. Quiescent thymocytes resemble resting hepatocytes in that most of the oxygen consumption remains unexplained. In constrast, the pattern of energy metabolism in stimulated thymocytes is similar to that described for Ehrlich Ascites tumour cells and splenocytes, which may also be in an activated state. Most of the oxygen consumption is accounted for, so the unexplained process(es) in unstimulated cells shut(s) off on stimulation.

Electron Transport and Coupled Energy Generation in Pseudomonas saccharophila

1971 ◽  
Vol 49 (11) ◽  
pp. 1175-1182 ◽  
Author(s):  
M. Ishaque ◽  
A. Donawa ◽  
M. I. H. Aleem
Keyword(s):  
Oxygen Consumption ◽  
Electron Transport ◽  
Cytochrome C ◽  
Atp Synthesis ◽  
Succinate Oxidation ◽  
Atp Formation ◽  
Low Concentrations ◽  
Oxidase Enzyme ◽  
Succinate Oxidase ◽  
Pseudomonas Saccharophila

The respiratory chain system of heterotrophically grown Pseudomonas saccharophila contained cytochromes of the b, c, a, and o types and also the NADH and succinate oxidase enzyme systems. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of NADH, succinate, and ascorbate (plus cytochrome c). The P/O ratios were in the range of 1.00 for generated NADH, 0.29 for added NADH, 0.50 for succinate, and 0.25 for ascorbate (plus cytochrome c).The oxidative phosphorylation was uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonyl cyanide phenylhydrazone, and dicumarol without any inhibition of oxygen consumption. Phosphorylation coupled to NADH oxidation was completely inhibited by the flavoprotein inhibitors such as rotenone, amytal, and atabrine; these inhibitors had no effect, however, on the ATP synthesis associated with succinate oxidation. Antimycin A or 2-n-nonyl-4-hydroxyquinoline-N-oxide as well as cyanide or azide at low concentrations completely inhibited the phosphate esterification coupled to the oxidation of NADH or succinate, but had little or no effect on the oxygen consumption. Relatively higher concentrations of oligomycin were required for a complete inhibition of the electron-transport-linked ATP formation.

scholarly journals Mechanical Ventilation Preserves Diaphragm Mitochondrial Function in a Rat Sepsis Model

2020 ◽  
Author(s):  
Pierre Eyenga ◽  
Damien Roussel ◽  
Benjamin Rey ◽  
Patrice Ndille ◽  
Loic Teulier ◽  
...  
Keyword(s):  
Mechanical Ventilation ◽  
Oxygen Consumption ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Oxidase Activity ◽  
Ros Generation ◽  
Mitochondrial Oxygen Consumption ◽  
Atp Production ◽  
Mitochondrial Ros ◽  
Mda Content

Abstract Background: To describe the effect of mechanical ventilation on diaphragm mitochondrial oxygen consumption, ATP production, reactive oxygen species (ROS) generation, and cytochrome-c oxidase activity and content, and their relationship to diaphragm strength in an experimental model of sepsis.Methods: A cecal ligation and puncture (CLP) protocol was performed in 12 rats while 12 controls underwent sham-operation. Half of the rats in each group were paralyzed and mechanically ventilated. We performed blood gas analysis and lactic acid assays 6 hours after surgery. Afterwards, we measured diaphragm strength and mitochondrial oxygen consumption, ATP and ROS generation, and cytochrome-c oxidase activity. We also measured malondialdehyde (MDA) content as an index of lipid peroxidation, and mRNA expression of the pro-inflammatory interleukin-1β (IL-1β) in diaphragms.Results: CLP rats showed severe hypotension, metabolic acidosis, and upregulation of diaphragm IL-1β mRNA expression. Compared to sham controls, spontaneously breathing CLP rats showed lower diaphragm force and increased susceptibility to fatigue, along with depressed mitochondrial oxygen consumption and ATP production and cytochrome-c oxidase activity. These rats also showed increased mitochondrial ROS generation and MDA content. Mechanical ventilation markedly restored mitochondrial oxygen consumption and ATP production in CLP rats; lowered mitochondrial ROS production by the complex 3; and preserved cytochrome-c oxidase activity.Conclusion: In an experimental model of sepsis, early initiation of mechanical ventilation restores diaphragm mitochondrial function.

Cytochrome aa3 in facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense

2005 ◽  
Vol 51 (8) ◽  
pp. 621-627 ◽  
Author(s):  
Takuro Nunoura ◽  
Yoshihiko Sako ◽  
Takayoshi Wakagi ◽  
Aritsune Uchida
Keyword(s):  
Oxygen Consumption ◽  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Gene Product ◽  
Respiratory Chain ◽  
Oxidase Activity ◽  
Terminal Oxidase ◽  
Hyperthermophilic Archaeon ◽  
Consumption Activity ◽  
Copper Oxidase

We partially purified and characterized the cytochrome aa3 from the facultatively aerobic and hyperthermophilic archaeon Pyrobaculum oguniense. This cytochrome aa3 showed oxygen consumption activity with N, N, N′, N′-tetramethyl-1,4-phenylenediamine and ascorbate as substrates, and also displayed bovine cytochrome c oxidase activity. These enzymatic activities of cytochrome aa3 were inhibited by cyanide and azide. This cytochrome contained heme As, but not typical heme A. An analysis of trypsin-digested fragments indicated that 1 subunit of this cytochrome was identical to the gene product of subunit I of the SoxM-type heme – copper oxidase (poxC). This is the first report of a terminal oxidase in hyperthermophilic crenarchaeon belonging to the order Thermoproteales.Key words: aerobic respiratory chain, terminal oxidase, Archaea, hyperthermophile, Pyrobaculum.

ConA induced changes in energy metabolism of rat thymocytes

1992 ◽  
Vol 12 (2) ◽  
pp. 109-114 ◽  
Author(s):  
F. Buttgereit ◽  
M. D. Brand ◽  
M. Müller
Keyword(s):  
Protein Synthesis ◽  
Oxygen Consumption ◽  
Energy Metabolism ◽  
Dna Synthesis ◽  
Atp Synthesis ◽  
Proton Leak ◽  
Ehrlich Ascites ◽  
Activated State ◽  
Ehrlich Ascites Tumour ◽  
Induced Changes

The influence of ConA on the energy metabolism of quiescent rat thymocytes was investigated by measuring the effects of inhibitors of protein synthesis, proteolysis, RNA/DNA synthesis, Na+K+-ATPase, Ca2+-ATPase and mitochondrial ATP synthesis on respiration. Only about 50% of the coupled oxygen consumption of quiescent thymocytes could be assigned to specific processes using two different media. Under these conditions the oxygen is mainly used to drive mitochondrial proton leak and to provide ATP for protein synthesis and cation transport, whereas oxygen consumption to provide ATP for RNA/DNA synthesis and ATP-dependent proteolysis was not measurable. The mitogen ConA produced a persistent increase in oxygen consumption by about 30% within seconds. After stimulation more than 80% of respiration could be assigned to specific processes. The major oxygen consuming processes of ConA-stimulated thymocytes are mitochondrial proton leak, protein synthesis and Na+K+-ATPase with about 20% each of total oxygen consumption, while Ca2+-ATPase and RNA/DNA synthesis contribute about 10% each. Quiescent thymocytes resemble resting hepatocytes in that most of the oxygen consumption remains unexplained. In contrast, the pattern of energy metabolism in stimulated thymocytes is similar to that described for Ehrlich Ascites tumour cells and splenocytes, which may also be in an activated state. Most of the oxygen consumption is accounted for, so the unexplained process(es) in unstimulated cells shut(s) off on stimulation.

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