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Sipos 2005 Cell Mol Neurobiol + ((1) Endothelial cells are permanently chal … (1) Endothelial cells are permanently challenged by altering pH in the blood, and oxidative damage could also influence the intracellular pH (pH(i)) of the endothelium. Cerebral microvascular endothelial cells form the blood-brain barrier (BBB) and pH(i) regulation of brain capillary endothelial cells is important for the maintenance of BBB integrity. The aim of this study was to address the pH regulatory mechanisms and the effect of an acute exposure to hydrogen peroxide (H2O2) on the pH regulation in primary rat brain capillary endothelial (RBCE) cells The RBCE monolayers were loaded with the fluorescent pH indicator BCECF and pH(i) was monitored by detecting the fluorescent changes. (2) The steady-state pH(i) of RBCE cells in HEPES-buffer (6.83 +/- 0.1) did not differ significantly from that found in bicarbonate-buffered medium (6.90 +/- 0.08). Cells were exposed to NH4CI to induce intracellular acidification and then the recovery to resting pH was studied. Half-recovery time after NH4Cl prepulse-induced acid load was significantly less in the bicarbonate-buffered medium than in the HEPES-medium, suggesting that in addition to the Na+ / H+ exchanger, HCO3- / Cl- exchange mechanism is also involved in the restoration of pH(i) after an intracellular acid load in primary RBCE cells. We used RT-PCR-reactions to detect the isoforms of Na+ / H+ exchanger gene family (NHE). NHE-1 -2, -3 and -4 were equally present, and there was no significant difference in the relative abundance of the four transcripts in these cells. (3) No pH(i) recovery was detected when the washout after an intracellular acid load occurred in nominally Na+ -free HEPES-buffered medium or in the presence of 10 microM 5-(N-ethyl-N-isopropyl)amiloride (EIPA), a specific inhibitor of Na+ / H+ exchanger. The new steady-state pH(i) were 6.37 +/- 0.02 and 6.60 +/- 0.02, respectively. (4) No detectable change was observed in the steady-state pH(i) in the presence of 100 microM H2O2; however, recovery from NH4Cl prepulse-induced intracellular acid load was inhibited when H2O2 was present in 50 or 100 microM concentration in the HEPES-buffered medium during NH4Cl washout. These data suggest that H2O2 is without effect on the activity of Na+ / H+ exchanger at rest, but could inhibit the function of the exchanger after an intracellular acid load.xchanger after an intracellular acid load.)
MiPNet25.14 TPP Analysis Template + ((2020) Excel template for TPP data analys … (2020) Excel template for TPP data analysis. Mitochondr Physiol Network 25.14(01):1-8. <div style="padding:0px;border: 1px solid #aaaaaa;margin-bottom:0px;margin-right:10px"><div style="font-size:100%;font-weight:bold;padding:0.2em;padding-right: 0.4em;padding-left: 0.4em;background-color:#eeeeee;border-bottom:1px solid #aaaaaa;text-align:left;">[[Image:O2k-support system.jpg|right|150px|link=http://wiki.oroboros.at/index.php/O2k-technical_support_and_open_innovation|O2k-technical support and open innovation]]: <big>Open the '''pdf document''' above.</big></div><div style="background-color:#ffffff;padding-top:0.2em;padding-right: 0.4em;padding-bottom: 0.2em;padding-left: 0.4em;">::::» Current O2k-series: '''[https://www.oroboros.at/index.php/product-category/products/o2k-packages/ NextGen-O2k Series XB and O2k Series J]'''::::» Current software versions DatLab 8.0: [[MitoPedia: DatLab]]::::* ''Further details:'' '''» [[MitoPedia: O2k-Open Support]]'''</div></div>:» Product: [[DatLab]], [[Oroboros O2k]], [[Oroboros O2k-Catalogue |O2k-Catalogue]]oboros O2k-Catalogue |O2k-Catalogue]])
Kagawa 1971 J Biol Chem + ( * Amorphous membrane fragments depleted i … * Amorphous membrane fragments depleted in P-lipids and cytochrome oxidase were isolated from bovine heart mitochondria and were reconstituted with P-lipids and coupling factors to yield vesicular structures. These vesicles catalyzed a 32Pi—ATP exchange and showed an induced enhancement of anilinonaphthalene sulfonate fluorescence on addition of ATP* 32Pi—ATP exchange and fluorescence enhancement were abolished by uncouplers of oxidative phosphorylation and by energy transfer inhibitors. The ATPase activity was inhibited by energy transfer inhibitors, but stimulated by uncouplers or by the combined action of nigericin and valinomycin in the presence of K+. Both ATPase activity and 32Pi—ATP exchange were inhibited by a specific antibody against coupling factor 1.* It was shown that the reconstitution of vesicular structures with functional activity required several hours. Rapid reconstitution resulted in inactive vesicles. Evidence for the formation of new vesicles from solubilized P-lipids was obtained by demonstrating inclusion of macromolecules such as 14C-labeled inulin or ferritin which could not be removed by washing.itin which could not be removed by washing. )
Cannon 2015 Fatty Acid Oxidation O2k-Network Discussion Forum + ( *Saponin permeabilized skeletal muscle fi … *Saponin permeabilized skeletal muscle fiber bundles*'''Protocol''':#0.5mM Malate#50 µM palmitoyl-CoA + 2mM carnitine#5mM ADP#From here on out, various combinations for titration protocol*Coupling states:#LEAK_M+Palmitoylcarnitine#P_M+Palmitoylcarnitine#P_M+Palmitoylcarnitine+S#E_O+CCCP titrations#E_S+Rot#ROX_AntimycinA_O+CCCP titrations #E_S+Rot #ROX_AntimycinA )
Nernst 1921 Nobel Lecture + (.. From the start of my scientific career … .. From the start of my scientific career the galvanic cell, the first form of which, the Volta pile, popularized physics in a single stroke and at the same time presented us with so many problems, appeared to me to merit especially further study. ..It was particularly disillusioning to find a man like Helmholtz returning repeatedly throughout his scientific career to his first love, the galvanic cell, which he had courted in his great youthful work "Erhaltung der Kraft" (The conservation of energy), without however succeeding in finding a satisfactory solution.As often in natural science the picture changed quite suddenly. New fruitful concepts appeared, through the interplay and extension of which most of the darkness has been to a large extent dispelled in a single stroke. Such means were Van ’t Hoff’s theory of osmotic pressure, Arrhenius’ theory of electrolytic dissociation, and finally many new approaches to the treatment of chemical equilibria, which, brilliantly presented, are to be found scattered throughout the first edition of Ostwald’s "Lehrbuch der Allgemeinen Chemie" (Textbook of general chemistry). So there arose in 1889 the osmotic theory of galvanic current generation, which has not been seriously challenged since it was put forward more than thirty years ago and has undergone no appreciable elaboration since its acceptance, surely a clear sign that it has so far satisfied scientific needs. ..The osmotic theory of current generation stipulates moreover that when a metal ion concentration is higher than consistent with the solution tension of the particular metal, on immersion of the metal, ions of the relevant metal electrode must go into solution, while conversely they must settle on the electrode when the reverse is the case.he electrode when the reverse is the case.)
Estabrook 1967 Methods Enzymol + (.. The convenience and simplicity of the p … .. The convenience and simplicity of the polarographic 'oxygen electrode' technique for measuring rapid changes in the rate of oxygen utilization by cellular and subcellular systems is now leading to its more general application in many laboratories. The types and design of oxygen electrodes vary, depending on the invetigator's ingenuity and specific requirements of the system under investigation.rements of the system under investigation.)
Gnaiger 1997 Transplant Proc + (0RGAN PRESERVATION under hypothermic ische … 0RGAN PRESERVATION under hypothermic ischemia is enhanced by storage solutions that protect the vascular endothelium from ischemia-reperfusion injury. Ischemia-reperfusion injury leads to primary graft failure and chronic rejection, and is commonly assessed by measuring endothelial activation and damage of the endothelial plasma membrane. However, corresponding primary intracellular events are little understood compared with the secondary cytokine/adhesion molecule cascade and inflammatory responses.1, 2 Because protection of intracellular and cell membrane function is fundamental for further improvement of organ preservation, we developed highresolution respirometry as a sensitive diagnostic test for mitochondrial and plasma membrane competence.3 Whereas the plasma membrane remained impermeable after clinically relevant cold storage times of 8 hours and 20 to 60 minutes of reoxygenation, mitochondrial function was impaired at several steps of the respiratory chain.l function was impaired at several steps of the respiratory chain.)
Majiene 2019 Nutrients + (1,4-naphthoquinones, especially juglone, a … 1,4-naphthoquinones, especially juglone, are known for their anticancer activity. However, plumbagin, lawsone, and menadione have been less investigated for these properties. Therefore, we aimed to determine the effects of plumbagin, lawsone, and menadione on C6 glioblastoma cell viability, ROS production, and mitochondrial function.Cell viability was assessed spectrophotometrically using metabolic activity method, and by fluorescent Hoechst/propidium iodide nuclear staining. ROS generation was measured fluorometrically using DCFH-DA. Oxygen uptake rates were recorded by the high-resolution respirometer Oxygraph-2k.Plumbagin and menadione displayed highly cytotoxic activity on C6 cells (IC50 is 7.7 ± 0.28 μM and 9.6 ± 0.75 μM, respectively) and caused cell death by necrosis. Additionally, they increased the amount of intracellular ROS in a concentration-dependent manner. Moreover, even at very small concentrations (1-3 µM), these compounds significantly uncoupled mitochondrial oxidation from phosphorylation impairing energy production in cells. Lawsone had significantly lower viability decreasing and mitochondria-uncoupling effect, and exerted strong antioxidant activity.Plumbagin and menadione exhibit strong prooxidant, mitochondrial oxidative phosphorylation uncoupling and cytotoxic activity. In contrast, lawsone demonstrates a moderate effect on C6 cell viability and mitochondrial functions, and possesses strong antioxidant properties.unctions, and possesses strong antioxidant properties.)
Leyssens 1996 J Physiol + (1. As ATP has a higher affinity for Mg2+ t … 1. As ATP has a higher affinity for Mg2+ than ADP, the cytosolic magnesium concentration rises upon ATP hydrolysis. We have therefore used the Mg(2+)-sensitive fluorescent indicator Magnesium Green (MgG) to provide an index of changing ATP concentration in single rat cardiomyocytes in response to altered mitochondrial state. 2. In response to FCCP, [Mg2+]i rose towards a plateau coincident with the progression to rigor, which signals ATP depletion. Contamination of the MgG signal by changes in intracellular free Ca2+ concentration (the KD of MgG for Ca2+ is 4.7 microM) was excluded by simultaneous measurement of [Ca2+]i and [Mg2+]i in cells dual loaded with fura-2 and MgG. The response to FCCP was independent of external Mg2+, confirming an intracellular source for the rise in [Mg2+]i. 3. Simultaneous measurements of mitochondrial NAD(P)H autofluorescence and mitochondrial potential (delta psi m; .-1 fluorescence) and of autofluorescence and MgG allowed closer study of the relationship between [Mg2+]i and mitochondrial state. Oligomycin abolished the FCCP-induced rise in [Mg2+]i without altering the change in autofluorescence. Thus, the rise in [Mg2+]i in response to FCCP is consistent with the release of intracellular Mg2+ following ATP hydrolysis by the mitochondrial F1F0-ATPase. 4. The rise in [Mg2+]i was correlated with cell-attached recordings of ATP-sensitive K+ channel (KATP) activity. In response to FCCP, an increase in KATP channel activity was seen only as [Mg2+]i reached a plateau. In response to blockade of mitochondrial respiration and glycolysis with cyanide (CN-) and 2-deoxyglucose (DOG), [Mg2+]i rose more slowly but again KATP channel opening increased only when [Mg2+]i reached a plateau and the cells shortened. 5. Oligomycin decreased the rate of rise of [Mg2+]i delayed the onset of rigor and increased the rate of mitochondrial depolarization in response to CN-_DOG. Thus, with blockade of mitochondrial respiration delta psi m is maintained by the mitochondrial F1F0-ATPase at the expense of ATP reserves. 6. In response to CN-_DOG, the initial rise in [Mg2+]i was accompanied by a small rise in [Ca2+]i. After [Mg2+]i reached a plateau and rigor developed, [Ca2+]i rose progressively. On reperfusion, in hypercontracted cells, [Ca2+]i recovered before [Mg2+]i and [ca2+]i oscillations were sustained while [Mg2+]i decreased. Thus on reperfusion, full recovery of [ATP]i is slow, but the activation of contractile elements and the restoration of [Ca2+]i does not require the re-establishment of millimolar concentrations of ATP.hment of millimolar concentrations of ATP.)
Satoh 1995 Br J Pharmacol + (1. Effects of 3-hydroxy-3-methylglutaryl c … 1. Effects of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, pravastatin and simvastatin, on the myocardial level of coenzyme Q10, and on mitochondrial respiration were examined in dogs. 2. Either vehicle (control), pravastatin (4 mg kg-1 day-1), or simvastatin (2 mg kg-1 day-1) was administered orally for 3 weeks. First, the myocardial tissue level of coenzyme Q10 was determined in the 3 groups. Second, ischaemia was induced by ligating the left anterior descending coronary artery (LAD) in anaesthetized open chest dogs, pretreated with the inhibitors. After 30 min of ischaemia, nonischaemic and ischaemic myocardium were removed from the left circumflex and LAD regions, respectively, and immediately used for isolation of mitochondria. The mitochondrial respiration was determined by polarography, with glutamate and succinate used as substrates. 3. Simvastatin significantly decreased the myocardial level of coenzyme Q10, but pravastatin did not. 4. Ischaemia decreased the mitochondrial respiratory control index (RCI) in both groups. Significant differences in RCI between nonischaemic and ischaemic myocardium were observed in the control and simvastatin-treated groups. 5. Only in the simvastatin-treated group did ischaemia significantly decrease the ADP/O ratio, determined with succinate. 6. The present results indicate that simvastatin but not pravastatin may cause worsening of the myocardial mitochondrial respiration during ischaemia, probably because of reduction of the myocardial coenzyme Q10 level.tion of the myocardial coenzyme Q10 level.)

(1. In succinate oxidation reactivated by a low concentration of adenosin)

Chance 1962 J Biol Chem + (1. In succinate oxidation reactivated by a … 1. In succinate oxidation reactivated by a low concentration of adenosine triphosphate, addition of small amounts of adenosine diphosphatc will lead to reestablishment of the inhibited state of succinate oxidation after a short burst of respiration.2. The inhibited state is not relieved by either phosphate or phosphate acceptors. 3. The inhibition is closely correlated with a high degree of oxidation of mitochondrial reduced diphosphopyridine nucleotide, which occurs immediately on addition of adenosine diphosphate and is followed by the inhibition of succinate oxidation after the oxidation or rather small amounts of succinate. 4. Oxidation of more than approximately two-thirds of the total diphosphopyridinc nuclcotide (DPN) reducible by succinate and adenosine triphosphate eventually leads to inhibition of succinate oxidation. 5. Based on independent evidence for a compartmentation of mitochondrial pyridine nucleotide (approximately one-third available to DPN-linked substrates), it is proposed that inhibi- tion occurs when oxidation of DPN in the compartment available to malate causes oxaloacetate formation sufficient to inhibit succinate oxidation. 6. The general possibility of DPN control of malate oxidation is considered with respect to the whole question of oxaloacetate regulation of the citric acid cycle.etate regulation of the citric acid cycle.)
Hatefi 1962 J Biol Chem-XLII + (1. It has been shown that the electron tra … 1. It has been shown that the electron transfer system in beef heart mitochondria may be reconstituted either totally or in any desired sequential segment by appropriate combinations of two or more of the four primary complexes that have been isolated in highly purified form in this laboratory. 2. The four enzyme systems that collectively comprise the complete machinery for transfer of electrons from reduced diphosphopyridine nucleotide (DPNH; =NADH) and succinate to oxygen re: I, DPNH-coenzyme Q reductase; II, succinic-coenzyme Q reductase; III, QH2-cytochrome ''c'' reductase; and IV, cytochrome ''c'' reductase. The specific inhibitors of each complex have been studied. 3. By appropriate combinations of the primary complexes the following secondary activities have been reconstituted: V, DPNH-cytochrome ''c'' reductase; VI, succinic-cytochrome ''c'' reductase; VII, DPNH, succinic-cytochrome c reductase; VIII, DPNH oxidase; IX, succinic oxidase; and X, DPNH, succinic oxidase activity. The general oxidation-reduction properties of the reconstituted systems, both in the presence and the absence of the usual specific inhibitors of the electron transfer system, are essentially the same as those found for the same activities in the intact mitochondria and in the integrated particles derived therefrom. 4. The reconstituted activities are quite stable to repeated freezing, thawing, and storage at -2O °C, and for the most part, when once formed, are not dissociated by dilution of the mixture or by centrifugation. The evidence supporting the conclusion that reconstitution necessarily involves a particle-particle interaction is discussed.article-particle interaction is discussed.)
Opalka 2004 Br Poult Sci + (1. M. iliotibialis (MIT) and M. pectoralis … 1. M. iliotibialis (MIT) and M. pectoralis (MP) of the BUT Big 6 and Kelly BBB turkey were characterised with respect to physical properties, mitochondrial function, metabolic state, morphology and meat quality.2. Mitochondrial enzyme activity and respiration rates in MP declined with increasing age while glycolytic enzyme activity remained nearly constant.3. There were no major differences between BUT Big 6 and Kelly BBB with respect to histological, histochemical or biochemical variables. In spite of the greater adult weight of BUT Big 6, body proportion was equal in both strains.4. In agreement with the histochemical findings MIT showed higher oxidative capacities, while glycolytic enzyme activity was higher in MP.5. Pyruvate was the best substrate for oxidative phosphorylation in MIT, but not in MP. Pyruvate dehydrogenase (PDH) activity was up to 15 times less in MP and blood lactate was correlated with intramuscular pH.6. Turkey breast muscle was restricted in its ability to oxidise pyruvate, especially in those animals that tended to develop intramuscular acidosis post mortem.7. It is concluded that the ''in vivo'' metabolic environment results in acidosis and impaired meat quality, at least in turkey M. pectoralis.quality, at least in turkey M. pectoralis.)
Claude 1946 J Exp Med + (1. Materials and technical procedures invo … 1. Materials and technical procedures involved in the preparation of liver suspensions have been described and discussed. 2. Liver extracts prepared by the present method appear to contain almost exclusively elements of cytoplasmic origin and can be considered to represent, on a large scale, the cytoplasm of liver cells.large scale, the cytoplasm of liver cells.)
Wilson 1970 Biochim Biophys Acta + (1. Oxidation of NADH by fumarate coupled t … 1. Oxidation of NADH by fumarate coupled to synthesis of ATP was found to occur in cyanide-poisoned rat heart submitochondrial particles. The reaction was inhibited by amytal, thenoyltrifluoroacetone and malonate, indicating the involvement of a portion of the electron transfer chain.2. Cytochrome b became oxidized (while the other cytochromes remained reduced) during the oxidation of NADH by fumarate, suggesting that cytochrome b is part of the reaction pathway.3. Succinate was recovered as the reaction product and accounted for the NADH oxidized.4. The P/2e ratios indicate that one ATP was produced for each pair of electrons transferred to fumarate.5. The reaction was also demonstrated to be present in liver and gastrocnemius muscle of rat. The reaction rate in heart was 2.0 times that of gastrocnemius and 3.3 times that of liver. These differences are not related to the activities of NADH or succinate dehydrogenase.6. The ubiquitous nature of this reaction suggests that it could serve as an important physiological mechanism for generating extra glycolytic energy during periods of anoxia.lycolytic energy during periods of anoxia.)
Boveris 1973 Biochem J + (1. Pigeon heart mitochondria produce H(2)O … 1. Pigeon heart mitochondria produce H(2)O(2) at a maximal rate of about 20 nmol/min per mg of protein. 2. Succinate-glutamate and malate-glutamate are substrates which are able to support maximal H(2)O(2) production rates. With malate-glutamate, H(2)O(2) formation is sensitive to rotenone. Endogenous substrate, octanoate, stearoyl-CoA and palmitoyl-carnitine are by far less efficient substrates. 3. Antimycin A exerts a very pronounced effect in enhancing H(2)O(2) production in pigeon heart mitochondria; 0.26 nmol of antimycin A/mg of protein and the addition of an uncoupler are required for maximal H(2)O(2) formation. 4. In the presence of endogenous substrate and of antimycin A, ATP decreases and uncoupler restores the rates of H(2)O(2) formation. 5. Reincorporation of ubiquinone-10 and ubiquinone-3 to ubiquinone-depleted pigeon heart mitochondria gives a system in which H(2)O(2) production is linearly related to the incorporated ubiquinone. 6. The generation of H(2)O(2) by pigeon heart mitochondria in the presence of succinate-glutamate and in metabolic [[State 4]] has an optimum pH value of 7.5. In States 1 and 3u, and in the presence of antimycin A and uncoupler, the optimum pH value is shifted towards more alkaline values. 7. With increase of the partial pressure of O(2) to the hyperbaric region the formation of H(2)O(2) is markedly increased in pigeon heart mitochondria and in rat liver mitochondria. With rat liver mitochondria and succinate as substrate in State 4, an increase in the ''p''O(2) up to 1.97 MPa (19.5 atm) increases H(2)O(2) formation 10-15-fold. Similar ''p''O(2) profiles were observed when rat liver mitochondria were supplemented either with antimycin A or with antimycin A and uncoupler. No saturation of the system with O(2) was observed up to 1.97 MPa (19.5 atm). By increasing the ''p''O(2) to 1.97 MPa (19.5atm), H(2)O(2) formation in pigeon heart mitochondria with succinate as substrate increased fourfold in metabolic State 4, with antimycin A added the increase was threefold and with antimycin A and uncoupler it was 2.5-fold. In the last two saturation of the system with oxygen was observed, with an apparent ''K''(m) of about 71 kPa (0.7-0.8 atm) and a ''V''(max) of 12 and 20 nmol of H(2)O(2)/min per mg of protein. 8. It is postulated that in addition to the well-known flavin reaction, formation of H(2)O(2) may be due to interaction with an energy-dependent component of the respiratory chain at the cytochrome ''b'' level.atory chain at the cytochrome ''b'' level.)
Mitchell 1967 Biochem J + (1. Pulses of acidity of the outer aqueous … 1. Pulses of acidity of the outer aqueous phase of rat liver mitochondrial suspensions induced by pulses of respiration are due to the translocation of H(+) (or OH(-)) ions across the osmotic barrier (M phase) of the cristae membrane and cannot be attributed to the formation (with acid production) of a chemical intermediate that subsequently decomposes. 2. The effective quantity of protons translocated per bivalent reducing equivalent passing through the succinate-oxidizing and beta-hydroxybutyrate-oxidizing spans of the respiratory chain are very close to 4 and 6 respectively. These quotients are constant between pH5.5 and 8.5 and are independent of changes in the ionic composition of the mitochondrial suspension medium provided that the conditions permit the accurate experimental measurement of the proton translocation. 3. Apparent changes in the -->H(+)/O quotients may be induced by conditions preventing the occurrence of the usual backlash; these apparent changes of -->H(+)/O are attributable to a very fast electrically driven component of the decay of the acid pulses that is not included in the experimental extrapolations. 4. Apparent changes in the -->H(+)/O quotients may also be induced by the presence of anions, such as succinate, malonate and phosphate, or by cations such as Na(+). These apparent changes of -->H(+)/O are due to an increase in the rate of the pH-driven decay of the acid pulses. 5. The uncoupling agents, 2,4-dinitrophenol, carbonyl cyanide p-trifluoromethoxyphenylhydrazone and gramicidin increase the effective proton conductance of the M phase and thus increase the rate of decay of the respiration-driven acid pulses, but do not change the initial -->H(+)/O quotients. The increase in effective proton conductance of the M phase caused by these uncouplers accounts quantitatively for their uncoupling action; and the fact that the initial -->H(+)/O quotients are unchanged shows that uncoupler-sensitive chemical intermediates do not exist between the respiratory-chain system and the effective proton-translocating mechanism. 6. Stoicheiometric acid-base changes associated with the activity of the regions of the respiratory chain on the oxygen side of the rotenone- and antimycin A-sensitive sites gives experimental support for a suggested configuration of loop 3.xperimental support for a suggested configuration of loop 3.)
Claude 1944 J Exp Med + (1. Rat tumor extracts, containing chiefly … 1. Rat tumor extracts, containing chiefly the cytoplasmic constituents of leukemic cells, were fractionated into three main portions, the different components separating in the centrifuge according to size. 2. Mitochondria were isolated by centrifugation at relatively low speed. Elementary composition of purified mitochondria was found to correspond to about 11.5 per cent nitrogen, 1.6 per cent phosphorus, and 27 per cent lipids. Phosphorus and nitrogen content of the lipid portion suggests that as much as 75 to 80 per cent of the lipids of mitochondria is represented by phospholipids. Tests for ribose nucleic acid were positive. 3. Microsomes were separated by means of centrifugation at 18,000 x g. A relation between the high phosphorus content of the microsomes and the marked basophilia of the cytoplasm of leukemic cells is suggested. 4. Phosphorus distribution in the tumor extract, and light absorption analysis of the third fraction, seem to demonstrate that nucleic acid was not present either in a free condition, or in the form of nucleoprotein of relatively low molecular weight. The nature of the results suggests that ribose nucleic acid occurs in the cytoplasm of leukemic cells only in association with formed elements of relatively large size, namely microsomes, and mitochondria.size, namely microsomes, and mitochondria.)
Ernster 1969 Eur J Biochem + (1. Submitochondrial particles were prepare … 1. Submitochondrial particles were prepared from beef‐heart mitochondria by sonication in the presence of EDTA. The particles were lyophilized and repeatedly extracted with pentane until no ubiquinone was found in the extract. Treatment of the ubiquinone‐depleted particles with pentane containing a suitable concentration of ubiquinone (ubiquinone‐50) and subsequent quick washing with ubiquinone‐free pentane resulted in a “re‐incorporation” of ubiquinone in an amount similar to that present in the original particles (3–6 nmoles/mg protein).2. The ubiquinone‐depleted particles exhibited very low or no succinate and NADH oxidase activities, which were restored upon the re‐incorporation of ubiquinone to the levels found in the lyophilized particles before extraction with pentane. Partial (about 50 %) extraction of ubiquinone resulted in markedly decreased succinate and NADH oxidase activities.3. Added cytochrome ''c'' did not replace ubiquinone in restoring the succinate or NADH oxidase activity of ubiquinone‐depleted particles. It stimulated the NADH oxidase, but not the succinate oxidase, activity of the “ubiquinone‐incorporated” particles, but the same stimulation occurred with the lyophilized particles before ubiquinone extraction. The normal, lyophilized, and “ubiquinone‐incorporated” particles contained equal amounts of both total and enzymatically reducible cytochromes.4. In the presence of KCN, NADH reduced the cytochromes, including cytochrome ''b'', only at insignificant rates in the ubiquinone‐depleted particles as compared to the normal and lyophilized preparations, and these rates were greatly stimulated upon the re‐incorporation of ubiquinone. Succinate caused a rapid partial (about 25 %) reduction of cytochrome ''b'', but not of the rest of the cytochromes, in the ubiquinone‐depleted particles. This reduction occurred also in the absence of KCN, and the fraction of cytochrome ''b'', so reduced was not reoxidized when succinate oxidation was inhibited by malonate. Evidence for the occurrence of such an enzymatically non‐oxidizable form of cytochrome ''b'' was also obtained in the normal, lyophilized and “ubiquinone‐incorporated” particles, but, in those cases, this cytochrome ''b'' was reduced by both succinate and NADH. In the presence of antimycin A, all cytochrome ''b'' in the ubiquinone‐depleted particles was rapidly reduced by succinate but not by NADH.5. The normal and lyophilized particles catalyzed a rotenone‐sensitive oxidation of NADH by fumarate. This reaction was completely absent from the ubiquinone‐depleted particles and was restored upon the re‐incorporation of ubiquinone.6. N,N,N′,N′‐Tetramethyl‐p‐phenylenediamine catalyzed an NADH and succinate oxidase activity in antimycin A‐inhibited particles. This NADH oxidase activity was partially sensitive to rotenone in the normal, lyophilized and “ubiquinone‐incorporated” particles, but completely rotenone‐insensitive in the ubiquinone‐depleted particles. All four types of particles were active in catalyzing the antimycin A‐sensitive oxidation of menadiol.7. It is concluded that uniquinone is essential for the interaction of succinate dehydrogenase, NADH dehydrogenase and cytochrome ''b'', and that this interaction is a requisite for the normal function of the respiratory chain. Functionally modified forms of cytochrome ''b'', arising as a consequence of structural damage or antimycin A treatment, are discussed in relation to existing information and proposals concerning the role of cytochrome ''b'' and ubiquinone in electron transport.'b'' and ubiquinone in electron transport.)
Henderson 1969 Biochem J + (1. The action of the antibiotics enniatin … 1. The action of the antibiotics enniatin A, valinomycin, the actin homologues, gramicidin, nigericin and dianemycin on mitochondria, erythrocytes and smectic mesophases of lecithin-dicetyl hydrogen phosphate was studied. 2. These antibiotics induced permeability to alkali-metal cations on all three membrane systems. 3. The ion specificity on each membrane system was the same. 4. Enniatin A, valinomycin and the actins did not induce permeability to protons, whereas nigericin and dianemycin rendered all three membrane systems freely permeable to protons. 5. Several differences were noted between permeability induced by nigericin and that induced by gramicidin. 6. The action of all these antibiotics on mitochondrial respiration could be accounted for by changes in passive ion permeability of the mitochondrial membrane similar to those induced in erythrocytes and phospholipid membranes, if it is assumed that a membrane potential is present in respiring mitochondria.tial is present in respiring mitochondria.)