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 The synthesis of hippurate from benzoate and glycine by rat liver mitochondria. Submitochondrial localization and kinetics

1977 ◽  
Vol 166 (1) ◽  
pp. 39-47 ◽  
Author(s):  
S J Gatley ◽  
H S A Sherratt
Keyword(s):  
Rat Liver ◽  
Atp Hydrolysis ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
O2 Consumption ◽  
Mitochondrial Content ◽  
Presence And Absence ◽  
The Individual ◽  
Good Agreement

1. Rat liver mitochondria make hippurate at up to 4 nmol/min per mg of protein. The rate of synthesis supported by oxidation of glutamate with exogenous Pi present is identical with that supported by ATP plus oligomycin. Lower rates were obtained with other respiratory substrates, and when glutamate was used without Pi. 2. A matrix localization for hippurate synthesis is indicated by the latency of benzoyl-CoA synthetase and glycine N-acyltransferase to their extramitochondrial substrates, failure of exogenous benzoyl-CoA to inhibit incorporation of [14C]hippurate and inhibition of hippurate synthesis supported by ATP, but not glutamate, by carboxyatractyloside. 3. The relative activities of the individual enzymes and the mitochondrial content of benzoyl-CoA in the presence and absence of glycine suggest that hippurate synthesis is rate-limited by formation of benzoyl-CoA. 4. The increases in rates of ATP hydrolysis and of O2 consumption on the addition of benzoate and glycine were in good agreement with those required to support hippurate synthesis. The increase in respiration indicates that State-4 respiration [Chance & Williams (1957) Adv. Enzymol 17, 65-134] is not used, with these conditions, for ATP synthesis.

scholarly journals Oxidative phosphorylation. The relation between the specific binding of trimethlytin and triethyltin to mitochondria and their effects on various mitochondrial functions

1971 ◽  
Vol 124 (1) ◽  
pp. 221-234 ◽  
Author(s):  
W. N. Aldridge ◽  
B. W. Street
Keyword(s):  
Oxygen Uptake ◽  
Binding Site ◽  
Atp Hydrolysis ◽  
Specific Binding ◽  
Atp Synthesis ◽  
Low Concentrations ◽  
Mitochondrial Functions ◽  
Biological Specificity ◽  
Approach Zero ◽  
A Site

1. A binding site (site 1) is present in mitochondria with affinity for trimethyltin and triethyltin adequate for a site to which they could be attached when the processes of energy conservation are inhibited. 2. The quantitative relationships between the binding of trimethyltin and triethyltin to site 1 and their effects on various mitochondrial functions have been examined. 3. ATP synthesis linked to the oxidation of pyruvate, succinate and intramitochondrial substrate, ATP synthesis and oxygen uptake (succinate or pyruvate as substrate) stimulated by uncoupling agents are all inhibited by trimethyltin and triethyltin; when inhibition is less than 50% the ratio (percentage inhibition)/(percentage of binding site 1 complexed) is approx. 10:1. 4. ATP synthesis linked to the oxidation of reduced cytochrome c (ascorbate+NNN′N′-tetramethyl-p-phenylenediamine), ATP hydrolysis and oxygen uptake in the presence of low concentrations of trimethyltin and triethyltin approach zero activity as the proportion of binding site 1 complexed approaches 100%. 5. Possible interpretations of these findings are discussed with reference to published arrangements for coupling of electron transport to ATP synthesis and also to our present knowledge of the chemical and biological specificity of trialkyltin compounds.

scholarly journals The decrease of mitochondrial substrate uptake caused by trialkyltin and trialkyl-lead compounds in chloride media and its relevance to inhibition of oxidative phosphorylation

1975 ◽  
Vol 146 (2) ◽  
pp. 465-471 ◽  
Author(s):  
D N Skilleter
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthesis ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Substrate Uptake ◽  
O2 Uptake ◽  
Lead Compounds ◽  
Mitochondrial Functions ◽  
Respiration Of Mitochondria

1. In a 100 mM-KCl medium (pH 6.8) containing ATP, triethyltin (1 muM) causes a decrease in the uptake of pyruvate, malate, citrate or β-hydroxybutyrate by rat liver mitochondria, but no decrease is observed in a 100 mM-KNO3 medium. This response is not modified by the presence of rotenone in the incubation medium. 2. In the KCl medium at least 1 muM-triethyltin is required to cause maximum inhibition of pyruvate uptake. 3. Trimethyltin, tributyltin and the trialkyl-lead analogues at 1 muM, to varying degrees, also cause a decrease in pyruvate uptake by mitochondria only in the KCl medium. 4. Triethyltin stimulates resting respiration of mitochondria with all the substrates tested in the KCl medium but not in the KNO3 medium, yet this stimulation of O2 uptake occurs under conditions when substrate uptake is decreased. 5. In contrast, both O2 uptake during state 3 respiration and ATP synthesis when linked to the oxidation of pyruvate, malate or citrate are strongly inhibited by 1 muM-triethyltin in a KCl medium, but O2 uptake and ATP synthesis during the oxidation of β-hydroxybutyrate are only slightly affected. In a KNO3 medium O2 uptake and ATP synthesis linked to the oxidation of all substrates are only slightly affected. 6. The relevance of the decrease in substrate uptake by mitochondria caused by triethyltin in a KCl medium to the greater sensitivity of various mitochondrial functions observed in vitro is discussed. It is concluded that decrease of matrix substrate content is probably not the major cause of the greater sensitivity of oxidative phosphorylation to triethyltin in a KCl medium observed previously.

scholarly journals Proton translocation by the mitochondrial cytochrome b-c1 complex is inhibited by NN′-dicyclohexylcarbodi-imide

1982 ◽  
Vol 206 (2) ◽  
pp. 419-421 ◽  
Author(s):  
B D Price ◽  
M D Brand
Keyword(s):  
Electron Transport ◽  
Cytochrome Oxidase ◽  
Cytochrome B ◽  
Rat Liver ◽  
Proton Translocation ◽  
Liver Mitochondria ◽  
Rat Liver Mitochondria ◽  
Mitochondrial Cytochrome ◽  
Low Concentrations ◽  
Mitochondrial Cytochrome B

NN'-Dicyclohexylcarbodi-imide at low concentrations decreases the H+/2e ratio for rat liver mitochondria over the span succinate to oxygen from 5.9 +/- 0.3 (mean +/- S.E.M.) to 4.0 +/- 0.1 and for the cytochrome b-c1 complex from 3.8 +/- 0.2 to 1.9 +/- 0.1, but has little effect on the H+/2e ratio of cytochrome oxidase. The decrease in stoicheiometry is due, not to uncoupling or inhibition of electron transport, but to inhibition of proton translocation. NN'-Dicyclohexylcarbodi-imide thus ‘decouples’ proton translocation in the cytochrome b-c1 complex.

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