scholarly journals The effect of chloroform on mitochondrial energy transduction

1996 ◽  
Vol 320 (3) ◽  
pp. 837-845 ◽  
Author(s):  
Lee-Feng CHIEN ◽  
Martin D. BRAND
Keyword(s):  
Electron Transport ◽  
Atp Hydrolysis ◽  
Electron Flow ◽  
Protonmotive Force ◽  
Rate Dependent ◽  
Carbonyl Cyanide ◽  
Apparent Decrease ◽  
Electron Transport Complexes ◽  
The Relationship ◽  
Flow Pathway

The effect of chloroform on mitochondrial respiration with succinate was investigated by applying the method of Brand, Chien and Diolez [(1994) Biochem. J. 297, 27–29] to examine whether chloroform causes redox slip (fewer protons pumped per electron transferred) during mitochondrial electron transport. N,N,N´,N´-Tetramethyl-p-phenylenediamine (TMPD), which lowers H+/O (the number of protons pumped to the external medium by the electron transport complexes per oxygen atom consumed) by altering the electron flow pathway, was investigated for comparison. Non-phosphorylating mitochondria that had been treated with 350 µM TMPD or 30 mM chloroform were titrated with malonate in the presence of submaximal concentrations of the uncoupler carbonyl cyanide m-chlorophenylhydrazone (CCCP). Linear relations between CCCP-induced extra respiration and protonmotive force were obtained. These results showed that there was no measurable protonmotive force-dependent or rate-dependent slip in mitochondria treated with either TMPD or chloroform. However, both TMPD and chloroform seemed to decrease H+/O in a manner independent of protonmotive force and rate. The relationship between non-phosphorylating respiration and protonmotive force was simulated in mitochondria of which 25% of the total population were assumed to have been broken. The simulation showed that the apparent decrease in H+/O on the addition of TMPD or chloroform to mitochondria could be in principle accounted for by breakage. Assays of mitochondrial breakage (ATP hydrolysis in the presence of atractyloside and oxidation of exogenous NADH) showed that chloroform broke mitochondria but TMPD did not. We conclude that chloroform changes the measured H+/O as an artifact by causing mitochondrial breakage and does not cause measurable redox slip, whereas TMPD genuinely lowers H+/O.

scholarly journals Energy-conserving reactions in phosphorylating electron-transport particles from Nitrobacter winogradskyi. Activation of nitrite oxidation by the electrical component of the protonmotive force

1976 ◽  
Vol 156 (3) ◽  
pp. 481-491 ◽  
Author(s):  
J G Cobley
Keyword(s):  
Electron Transport ◽  
Reaction Medium ◽  
Respiratory Control ◽  
Nadh Oxidation ◽  
Protonmotive Force ◽  
Maximal Effect ◽  
Carbonyl Cyanide ◽  
Electrical Component ◽  
Stimulation Of ◽  
No2 Oxidation

1. In electron-transport particles (ET particles) prepared from Nitrobacter winogradskyi, the uncoupling agent carbonyl cyanide phenylhydrazone increased the rate of NADH oxidation but decreased the rate of oxidation of NO2-. Its effectiveness in stimulating NADH oxidation closely paralleled its effectiveness in inhibiting NO2- oxidation. 2. In the presence of ADP and phosphate the oxidation of NADH was stimulated, whereas the oxidation of NO2- was inhibited. In the presence of excess of Pi the concentration dependence with respect to ADP was the same for acceleration of NADH oxidation and inhibition of NO2- oxidation. 3. Oligomycin inhibited NADH oxidation and stimulated the oxidation of NO2-. The concentration of oligomycin required to produce half-maximal effect in both systems was the same. 4. The apparent Km for NO2- was not affected by ADP together with Pi, by uncoupling agent or by oligomycin. 5. With NADH as substrate, classical respiratory control was observed. With NO2- as substrate the respiratory-control ratio was less than unity. 6. A reversible uptake of H+ accompanied the oxidation of NO2- by ET particles. 7. In the presence of NH4Cl or cyclohexylamine hydrochloride, H+ uptake was abolished and increased rates of NO2- oxidation were observed. When valinomycin was present in the reaction medium, low concentrations of NH4Cl inhibited NO2- oxidation. 8. Pretreatment of ET particles with oligomycin enhanced the stimulation of NO2- oxidation induced by NH4Cl or by cyclohexylamine hydrochloride. Pretreatment with the uncoupler carbonyl cyanide phenylhydrazone prevented these stimulations. 9. In the presence of dianemycin together with K+, the uptake of H+ was abolished and the rate of NO2- oxidation was increased. In contrast, in the presence of valinomycin together with K+, the uptake of H+ was increased, and the rate of NO2- oxidation decreased. 10. Sodium tetraphenylboron was found to be an inhibitor of NO2- oxidation, but caused a stimulation of NADH oxidation which was dependent on the presence of NH4Cl or cyclohexylamine hydrochloride. 11. It is concluded that the enhanced rate of NO2- oxidation observed in the absence of energy-dissipating processes clearly relates to some state before the involvement of adenine nucleotides, and it is suggested that the oxidation of NO2- generates a protonmotive force, the electrical component of which controls the rate of NO2- oxidation.

scholarly journals Oxidative phosphorylation. The effect of anions on the inhibition by triethyltin of various mitochondrial functions, and the relationship between this inhibition and binding of triethyltin

1972 ◽  
Vol 127 (1) ◽  
pp. 51-59 ◽  
Author(s):  
M. S. Rose ◽  
W. N. Aldridge
Keyword(s):  
Electron Transport ◽  
Oxygen Uptake ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Hydroxide Ion ◽  
Mitochondrial Functions ◽  
Relationship Of ◽  
The Relationship

1. The binding of triethyltin to rat liver mitochondria is unaffected by the nature of the predominant anion in the incubation medium. 2. With chloride, bromide or iodide as the predominant anion, ATP synthesis linked to the oxidation of pyruvate or succinate and ATP hydrolysis stimulated by 2,4-dinitrophenol are much more sensitive to triethyltin than they are when nitrate or isethionate is the predominant anion. 3. When nitrate or isethionate is the predominant anion, oxygen uptake stimulated by 2,4-dinitrophenol is not inhibited by triethyltin. 4. In the presence of nitrate or isethionate anions, inhibition of ATP synthesis is directly related to the binding of triethyltin to mitochondria. 5. The relationship of the above effects to the anion–hydroxide ion exchange mediated by triethyltin and the relevance of this to published arrangements for coupling of electron transport to ATP synthesis are discussed.

scholarly journals Glutamate uptake into synaptic vesicles of bovine cerebral cortex and electrochemical potential difference of proton across the membrane

1989 ◽  
Vol 258 (2) ◽  
pp. 499-504 ◽  
Author(s):  
J Shioi ◽  
S Naito ◽  
T Ueda
Keyword(s):  
Cerebral Cortex ◽  
Synaptic Vesicles ◽  
Driving Force ◽  
Significant Contribution ◽  
Atp Hydrolysis ◽  
Glutamate Uptake ◽  
Protonmotive Force ◽  
Chromaffin Granule ◽  
Carbonyl Cyanide ◽  
Disulphonic Acid

Measurements have been made of the ATP-dependent membrane potential (delta psi) and pH gradient (delta pH) across the membranes of the synaptic vesicles purified from bovine cerebral cortex, using the voltage-sensitive dye bis[3-propyl-5-oxoisoxazol-4-yl]pentamethine oxanol and the delta pH-sensitive fluorescent dye 9-aminoacridine respectively. A pre-existing small delta pH (inside acidic) was detected in the synaptic vesicles, but no additional significant contribution by MgATP to delta pH was observed. In contrast, delta psi (inside positive) increased substantially upon addition of MgATP. This ATP-dependent delta psi was reduced by thiocyanate anion (SCN-), a delta psi dissipator, or carbonyl cyanide p-(trifluoromethoxy)phenylhydrazone (FCCP), a protonmotive-force dissipator. Correspondingly, a substantially larger glutamate uptake occurred in the presence of MgATP, which was inhibited by SCN- and FCCP. A nonhydrolysable analogue of ATP, adenosine 5′-[beta gamma-methylene]triphosphate, did not substitute for ATP in either delta psi generation or glutamate uptake. The results support the hypothesis that a H+-pumping ATPase generates a protonmotive force in the synaptic vesicles at the expense of ATP hydrolysis, and the protonmotive force thus formed provides a driving force for the vesicular glutamate uptake. The delta psi generation by ATP hydrolysis was not affected by orthovanadate, ouabain or oligomycin, but was inhibited by N-ethylmaleimide, quercetin, trimethyltin, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole and 4-acetamido-4′-isothiocyanostilbene-2,2′-disulphonic acid. These results indicate that the H+-pumping ATPase in the synaptic vesicle is similar to that in the chromaffin granule, platelet granule and lysosome.

scholarly journals Reduction of cytochromes by nitrite in electron-transport particles from Nitrobacter winogradskyi: proposal of a mechanism for H+ translocation

1976 ◽  
Vol 156 (3) ◽  
pp. 493-498 ◽  
Author(s):  
J G Cobley
Keyword(s):  
Electron Transport ◽  
Cytochrome C ◽  
Respiratory Chain ◽  
Single Electron ◽  
Reduced Form ◽  
Protonmotive Force ◽  
Carbonyl Cyanide ◽  
Cytochromes C ◽  
Electrical Component ◽  
No2 Oxidation

1. A novel component in the respiratory chain of Nitrobacter winogradskyi was identified. This component absorbs maximally at 552.5 nm when in its reduced form, has an Eo' (pH7.0) value of-110mV and undergoes reduction by a mechanism involving the transfer of a single electron. 2. Degrees of reduction of cytochromes c and a1 in electron-transport (ET) particles were monitored during the course of NO2- oxidation, and the effects of ADP together with Pi, oligomycin and of carbonyl cyanide phenylhydrazone were determined. 3. The influences of ionophorous antibiotics, NH4Cl and cyclohexylamine hydrochloride on the reductions of cytochromes c and a1 by NO2- indicate that the flow of reducing equivalents from cytochrome a1 (+350mV) to cytochrome c (+270mV) is facilitated by deltapsi, the electrical component of the protonmotive force. 4. Cytochromes c and a1 in ET particles are reduced by the non-physiological reductant KBH4 in a manner similar to that observed with the physiological reductant NO2-. 5. To account both for the observed cytochrome reductions and for the translocation of H+ ions which accompanies NO2- oxidation, a mechanism is proposed which involves the transfer of a hydride equivalent (H+ plus 2e) inward across the membrane of the ET particle in response to deltapsi.

Interaction of Photosystem II Herbicides with Bicarbonate and Formate in Their Effects on Photosynthetic Electron Flow

1984 ◽  
Vol 39 (5) ◽  
pp. 374-377 ◽  
Author(s):  
J. J. S. van Rensen
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Flow ◽  
Photosynthetic Electron Transport ◽  
Hill Reaction ◽  
Amaranthus Hybridus ◽  
Apparent Affinity ◽  
Photosynthetic Electron Flow ◽  
Different Characteristics ◽  
The Hill

The reactivation of the Hill reaction in CO2-depleted broken chloroplasts by various concentrations of bicarbonate was measured in the absence and in the presence of photosystem II herbicides. It appears that these herbicides decrease the apparent affinity of the thylakoid membrane for bicarbonate. Different characteristics of bicarbonate binding were observed in chloroplasts of triazine-resistant Amaranthus hybridus compared to the triazine-sensitive biotype. It is concluded that photosystem II herbicides, bicarbonate and formate interact with each other in their binding to the Qв-protein and their interference with photosynthetic electron transport.

Effect of Magnesium and Calcium Ions on the Photoelectron Transport Activity of Low-Salt Suspended Hydrilla verticillata Thylakoids: Possible Sites of Cation Interaction

1998 ◽  
Vol 53 (9-10) ◽  
pp. 849-856
Author(s):  
Sujata R. Mishra ◽  
Surendra Chandra Sabat
Keyword(s):  
Electron Transport ◽  
Photosystem Ii ◽  
Electron Donor ◽  
Water Oxidation ◽  
Electron Flow ◽  
Hydrilla Verticillata ◽  
Transport Activity ◽  
Low Salt ◽  
Electron Transport Activity ◽  
Stimulation Of

Stimulatory effect of divalent cations like calcium (Ca2+) and magnesium (Mg2+) was investigated on electron transport activity of divalent cation deficient low-salt suspended (LS) thylakoid preparation from a submerged aquatic angiosperm, Hydrilla verticillata. Both the cations stimulated electron transport activity of LS-suspended thylakoids having an intact water oxidation complex. But in hydroxylamine (NH2OH) - or alkaline Tris - washed thylakoid preparations (with the water oxidation enzyme impaired), only Ca2+ dependent stimulation of electron transport activity was found. The apparent Km of Ca2+ dependent stimulation of electron flow from H2O (endogenous) or from artificial electron donor (exogenous) to dichlorophenol indophenol (acceptor) was found to be identical. Calcium supported stimulation of electron transport activity in NH2OH - or Tris - washed thylakoids was electron donor selective, i.e., Ca2+ ion was only effective in electron flow with diphenylcarbazide but not with NH2OH as electron donor to photosystem II. A magnesium effect was observed in thylakoids having an intact water oxidation complex and the ion became unacceptable in NH2OH - or Tris - washed thylakoids. Indirect experimental evidences have been presented to suggest that Mg2+ interacts with the water oxidation complex, while the Ca2+ interaction is localized betw een Yz and reaction center of photosystem II.

scholarly journals Thermodynamic control of electron flux through mitochondrial cytochrome bc1 complex

1985 ◽  
Vol 225 (2) ◽  
pp. 399-405 ◽  
Author(s):  
G C Brown ◽  
M D Brand
Keyword(s):  
Liver Mitochondria ◽  
Cytochrome Bc1 ◽  
Rat Liver Mitochondria ◽  
Protonmotive Force ◽  
Bc1 Complex ◽  
Thermodynamic Control ◽  
Cytochrome Bc1 Complex ◽  
Redox States ◽  
Force Ratio ◽  
Carbonyl Cyanide

The redox states of exogenously added ubiquinone-2 and cytochrome c, and the protonmotive force (delta p) of rat liver mitochondria were measured as the respiration rate was titrated with the uncoupler carbonyl cyanide p-trifluoromethoxyphenyl-hydrazone. The force ratio delta Eh/delta p across the bc1 complex was close to 1:1 in State 4, indicating an H+/e- stoichiometry of 1:1 for the cytochrome bc1 complex, excluding protons moved by pool ubiquinone. Assuming a constant stoichiometry the rate of electron transport increased linearly with the disequilibrium (delta Eh - delta p) across the complex.

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