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Abstract
ATP is required for mammalian cells to remain viable and to perform genetically programmed functions. Maintenance of the ΔG′ATP hydrolysis of −56 kJ/mole is the endpoint of both genetic and metabolic processes required for life. Various anomalies in mitochondrial structure and function prevent maximal ATP synthesis through OxPhos in cancer cells. Little ATP synthesis would occur through glycolysis in cancer cells that express the dimeric form of pyruvate kinase M2. Mitochondrial substrate level phosphorylation (mSLP) in the glutamine-driven glutaminolysis pathway, substantiated by the succinate-CoA ligase reaction in the TCA cycle, can partially compensate for reduced ATP synthesis through both OxPhos and glycolysis. A protracted insufficiency of OxPhos coupled with elevated glycolysis and an auxiliary, fully operational mSLP, would cause a cell to enter its default state of unbridled proliferation with consequent dedifferentiation and apoptotic resistance, i.e., cancer. The simultaneous restriction of glucose and glutamine offers a therapeutic strategy for managing cancer.
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Affiliation(s)
- Thomas N Seyfried
- Biology Department, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA
| | - Gabriel Arismendi-Morillo
- Electron Microscopy Laboratory, Biological Researches Institute, Faculty of Medicine, University of Zulia, Maracaibo, Venezuela
| | - Purna Mukherjee
- Biology Department, Boston College, 140 Commonwealth Avenue, Chestnut Hill, MA 02467, USA
| | - Christos Chinopoulos
- Department of Medical Biochemistry, Semmelweis University, Budapest, 1094, Hungary
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Muller AWJ. Cancer is an adaptation that selects in animals against energy dissipation. Med Hypotheses 2017; 104:104-115. [PMID: 28673566 DOI: 10.1016/j.mehy.2017.05.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 04/30/2017] [Accepted: 05/25/2017] [Indexed: 02/06/2023]
Abstract
As cancer usually follows reproduction, it is generally assumed that cancer does not select. Graham has however argued that juvenile cancer, which precedes reproduction, could during evolution have implemented a "cancer selection" that resulted in novel traits that suppress this juvenile cancer; an example is protection against UV sunlight-induced cancer, required for the emergence of terrestrial animals from the sea. We modify the cancer selection mechanism to the posited "cancer adaptation" mechanism, in which juvenile mortality is enhanced through the diminished care received by juveniles from their (grand) parents when these suffer from cancer in old age. Moreover, it is posited that the cancer adaptation selects against germline "dissipative genes", genes that result in enhanced free energy dissipation. Cancer's progression is interpreted as a cascade at increasing scale of repeated amplification of energy dissipation, a cascade involving heat shock, the Warburg effect, the cytokine IL-6, tumours, and hypermetabolism. Disturbance of any physiological process must enhance energy dissipation if the animal remains functioning normally, what explains multicausality, why "everything gives you cancer". The hypothesis thus comprises two newly invoked partial processes-diminished (grand) parental care and dissipation amplification-and results in a "selection against enhanced energy dissipation" which gives during evolution the benefit of energy conservation. Due to this benefit, cancer would essentially be an adaptation, and not a genetic disease, as assumed in the "somatic mutation theory". Cancer by somatic mutations is only a side process. The cancer adaptation hypothesis is substantiated by (1) cancer's extancy, (2) the failure of the somatic mutation theory, (3) cancer's initiation by a high temperature, (4) the interpretation of cancer's progression as a thermal process, and (5) the interpretation of tumours as organs that implement thermogenesis. The hypothesis could in principle be verified by monitoring in a population over several generations (1) the presence of dissipative genes, (2) the incidence of cancer, and (3) the beneficial effect of dissipative gene removal by cancer on starvation/famine survival.
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Affiliation(s)
- Anthonie W J Muller
- Synthetic Systems Biology and Nuclear Organization, Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 904, 1098 XH Amsterdam, The Netherlands.
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Seyfried TN, Flores R, Poff AM, D'Agostino DP, Mukherjee P. Metabolic therapy: a new paradigm for managing malignant brain cancer. Cancer Lett 2014; 356:289-300. [PMID: 25069036 DOI: 10.1016/j.canlet.2014.07.015] [Citation(s) in RCA: 127] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 07/09/2014] [Accepted: 07/10/2014] [Indexed: 01/18/2023]
Abstract
Little progress has been made in the long-term management of glioblastoma multiforme (GBM), considered among the most lethal of brain cancers. Cytotoxic chemotherapy, steroids, and high-dose radiation are generally used as the standard of care for GBM. These procedures can create a tumor microenvironment rich in glucose and glutamine. Glucose and glutamine are suggested to facilitate tumor progression. Recent evidence suggests that many GBMs are infected with cytomegalovirus, which could further enhance glucose and glutamine metabolism in the tumor cells. Emerging evidence also suggests that neoplastic macrophages/microglia, arising through possible fusion hybridization, can comprise an invasive cell subpopulation within GBM. Glucose and glutamine are major fuels for myeloid cells, as well as for the more rapidly proliferating cancer stem cells. Therapies that increase inflammation and energy metabolites in the GBM microenvironment can enhance tumor progression. In contrast to current GBM therapies, metabolic therapy is designed to target the metabolic malady common to all tumor cells (aerobic fermentation), while enhancing the health and vitality of normal brain cells and the entire body. The calorie restricted ketogenic diet (KD-R) is an anti-angiogenic, anti-inflammatory and pro-apoptotic metabolic therapy that also reduces fermentable fuels in the tumor microenvironment. Metabolic therapy, as an alternative to the standard of care, has the potential to improve outcome for patients with GBM and other malignant brain cancers.
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Affiliation(s)
| | | | - Angela M Poff
- Department of Molecular Pharmacology and Physiology, University of South Florida, 33612 Tampa, FL, USA
| | - Dominic P D'Agostino
- Department of Molecular Pharmacology and Physiology, University of South Florida, 33612 Tampa, FL, USA
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Seyfried TN, Marsh J, Shelton LM, Huysentruyt LC, Mukherjee P. Is the restricted ketogenic diet a viable alternative to the standard of care for managing malignant brain cancer? Epilepsy Res 2012; 100:310-26. [DOI: 10.1016/j.eplepsyres.2011.06.017] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Revised: 05/31/2011] [Accepted: 06/03/2011] [Indexed: 12/13/2022]
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5
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Oxygen Utilization and Toxicity in the Lungs. Compr Physiol 2011. [DOI: 10.1002/cphy.cp030105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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6
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Bogucka K, Teplova VV, Wojtczak L, Evtodienko YV, Wojtczaka L [corrected to Wojtczak L]. Inhibition by Ca2+ of the hydrolysis and the synthesis of ATP in Ehrlich ascites tumour mitochondria: relation to the Crabtree effect. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1228:261-6. [PMID: 7893730 DOI: 10.1016/0005-2728(94)00188-b] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Phosphorylation of ADP and hydrolysis of ATP by isolated mitochondria from Ehrlich ascites tumour cells is greatly reduced when the mitochondria have been preloaded with Ca2+ (50 nmol/mg protein or more). Translocation of ADP is diminished in Ca(2+)-loaded mitochondria. However, ATPase in toluene-permeabilized mitochondria and in inside-out submitochondrial particles is also strongly inhibited by micromolar concentrations of Ca2+, indicating that, independently of adenine nucleotide transport, F1Fo-ATPase is also affected. ATP hydrolysis by submitochondrial particles depleted of the inhibitory subunit of F1Fo-ATPase (the Pullman-Monroy protein inhibitor) is insensitive to Ca2+; however, this sensitivity is restored when the particles are supplemented with the inhibitory subunit isolated from beef heart mitochondria. In view of the previous observations that glucose elicits in Ehrlich ascites tumour cells an increase of cytoplasmic free Ca2+ (Teplova, V.V., Bogucka, K., Czyz, A., Evtodienko, Yu.V., Duszyński, J. and Wojtczak, L. (1993) Biochem. Biophys. Res. Commun. 196, 1148-1154) and that this calcium is then taken up by mitochondria, resulting in a strong inhibition of coupled respiration (Evtodienko, Yu.V., Teplova, V.V., Duszyński, J., Bogucka, K. and Wojtczak, L. (1994) Cell Calcium 15, 439-446), the present results are discussed in terms of the mechanism of the Crabtree effect in tumour cells.
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Affiliation(s)
- K Bogucka
- Nencki Institute of Experimental Biology, Department of Cellular Biochemistry, Warsaw, Poland
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Beavis A. Upper and lower limits of the charge translocation stoichiometry of mitochondrial electron transport. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45553-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Lehninger AL, Reynafarje B, Hendler RW, Shrager RI. The H+/O ratio of proton translocation linked to the oxidation of succinate by mitochondria. Reply to a commentary. FEBS Lett 1985; 192:173-8. [PMID: 4065321 DOI: 10.1016/0014-5793(85)80102-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Costa, L.E., Reynafarje, B. and Lehninger, A.L. [(1984) J. Biol. Chem. 259, 4802-4811] have reported 'second-generation' measurements of the H+/O ratio approaching 8.0 for vectorial H+ translocation coupled to succinate oxidation by rat liver mitochondria. In a Commentary in this Journal [Krab, K., Soos, J. and Wikström, M. (1984) FEBS Lett. 178, 187-192] it was concluded that the measurements of Costa et al. significantly overestimated the true H+/O stoichiometry. It is shown here that the mathematical simulation on which Krab et al. based this claim is faulty and that data reported by Costa et al. had already excluded the criticism advanced by Krab et al. Also reported are new data, obtained under conditions in which the arguments of Krab et al. are irrelevant, which confirm that the H+/O ratio for succinate oxidation extrapolated to level flow is close to 8.
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Kelmer Bracht A, Alvarez M, Bracht A. Effects of Stevia rebaudiana natural products on rat liver mitochondria. Biochem Pharmacol 1985; 34:873-82. [PMID: 2858211 DOI: 10.1016/0006-2952(85)90769-5] [Citation(s) in RCA: 37] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The effects of several natural products extracted from the leaves of Stevia rebaudiana on rat liver mitochondria were investigated. The compounds used were stevioside (a non-caloric sweetener), steviolbioside, isosteviol and steviol. Total aqueous extracts of the leaves were also investigated. S. rebaudiana natural products inhibited oxidative phosphorylation, ATPase activity NADH-oxidase activity, succinate-oxidase activity, succinate dehydrogenase, and L-glutamate dehydrogenase. The ADP/O ratio was decreased. Substrate respiration (state II respiration) was increased at low concentrations (up to 0.5 mM) and inhibited at higher concentrations (1 mM or more). In uncoupled mitochondria, inhibition of substrate respiration was the only effect observed. Net proton ejection induced by succinate and swelling induced by several substrates were inhibited. Of the compounds investigated, the sweet principle stevioside was less active. It was concluded that, in addition to the inhibitory effects, S. rebaudiana natural products may also act as uncouplers of oxidative phosphorylation. The possible physiologic consequences of the ingestion of stevioside and S. rebaudiana aqueous extracts are discussed.
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The ATP-to-oxygen stoichiometries of oxidative phosphorylation by rat liver mitochondria. An analysis of ADP-induced oxygen jumps by linear nonequilibrium thermodynamics. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90666-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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11
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Villalobo A, Alexandre A, Lehninger AL. H+ stoichiometry of sites 1 + 2 of the respiratory chain of normal and tumor mitochondria. Arch Biochem Biophys 1984; 233:417-27. [PMID: 6091552 DOI: 10.1016/0003-9861(84)90463-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The mechanistic stoichiometry for vectorial H+ ejection coupled to electron transport through energy-conserving segments 1 + 2 was determined on cyanide-inhibited mitochondria from rat liver, rat heart, and Ehrlich ascites tumor cells, and on rat liver mitoplasts with ferricyanide or ferricytochrome c as electron acceptors. K+ (+ valinomycin) and Ca2+ were employed as permeant cations. Three different methods were employed. In the first, known pulses of ferricyanide were added, and the total H+ ejected was determined with a glass electrode. Such measurements gave H+/2e-values exceeding 7.0 for both normal and tumor mitochondria with beta-hydroxybutyrate and other NAD-linked substrates; uptake of Ca2+ was also measured and gave the expected q+/2e-ratios. The second type of measurement was initiated by addition of ferricytochrome c to rat liver mitoplasts, with H+ ejection monitored with the glass electrode and ferricytochrome c reduction by dual-wavelength spectrophotometry; the H+/2e-ratios generally exceeded 7.0. In the third type of measurement, mixing and dilution artifacts were eliminated by oxidizing ferrocytochrome c in situ with a small amount of ferricyanide. H+/2e-ratios for rat liver mitoplasts oxidizing beta-hydroxybutyrate consistently approached or exceeded 7.5. Over 150 measurements made under a variety of conditions gave observed H+/2e-ejection ratios significantly exceeding 7.0, which correlated closely with H+/2e-measurements on sites 1 + 2 + 3, sites 2 + 3, and site 2. Factors leading to the deficit of the observed ratios from the integral value 8 for sites 1 + 2 were discussed.
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Ramirez F, Tu SI, Chatterji PR, McKeever B, Marecek JF. Amine fluorescamine compounds inhibit oxidative phosphorylation in rat liver mitochondria. Arch Biochem Biophys 1984; 230:61-8. [PMID: 6231888 DOI: 10.1016/0003-9861(84)90086-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The reaction of fluorescamine with ammonia, benzylamine, o,p-dimethylbenzylamine, 2-phenylethylamine, p-aminobenzoic acid, and the mycosamine-containing macrolide antibiotic, amphotericin B, yield compounds which induce significant effects on mitochondrial activities. From their effects on energy-yielding processes which lead to transmembranous proton movements, the compounds may be divided into three classes. While all modifiers significantly inhibit proton movement induced by both ATP hydrolysis and electron transfer in mitochondria, their influence on the primary energy yielding steps are quite different. Class I modifiers, e.g., the compound made from amphotericin B, inhibit electron transfer but have no effect on the Pi release associated with ATP hydrolysis. Class II modifiers, e.g., the compound made from benzylamine, inhibit respiration but stimulate Pi release. Class III modifiers, e.g., the compound made from p-aminobenzoic acid, on the other hand, only slightly increase Pi release but have no effect on redox reactions. These and other effects of the modifiers are taken to mean that the proton movements and their associated energy-yielding processes are only linked indirectly. The effects of the modifiers on State 3 mitochondrial activities were also investigated. Although all the modifiers decrease the rates of both State 3 respiration and its coupled ATP synthesis, the efficiency of energy conversion measured by the P/O ratio remains unaltered.
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Stoichiometry of mitochondrial H+ translocation coupled to succinate oxidation at level flow. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)42917-6] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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14
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Lehninger AL. Proton and electric charge translocation in mitochondrial energy transduction. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1982; 148:171-86. [PMID: 7124514 DOI: 10.1007/978-1-4615-9281-5_14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Lazo PA. Amino acids and glucose utilization by different metabolic pathways in ascites-tumour cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 117:19-25. [PMID: 6790281 DOI: 10.1111/j.1432-1033.1981.tb06297.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The utilization of amino acids and glucose by ascites tumour cells has been studied in order to elucidate which are their relative roles as energy substrates or building blocks for biosynthetic purposes, as well as the quantitative contribution of the different metabolic pathways involved. 1. Glucose is utilized at a rate of 1.1 mumol x min-1 x g cells-1. 93% is transformed into lactate, 0.7% used by the pentose phosphate pathway, 1.5% by the tricarboxylic acid cycle and 2% is for lipid synthesis. 2. ATP production is derived: 78% from glucose conversion into lactate, 1% from glucose oxidation and 19% from glutamine oxidation. 3. Glucose starvation, in the presence of all amino acids, leads to a 70% decrease in the rate of protein synthesis, due to the drop in ATP levels. 4. Pentose phosphate pathway flux increases by 75% when glycolysing cells are incubated in the presence of all amino acids. 5. Pyruvate is decarboxylated at a rate of 66 nmol x min-1 x g cells-1, 45-80% of it is incorporated into lipids instead of being oxidized, depending on the incubation conditions. 6. Non-essential amino acids (aspartate and glutamate) are oxidized at a low rate. Glutamine is oxidized at a rate 20-times and 35-times that of glucose and glutamate respectively. Glutamine can not replace glucose as the main energy source. 7. Leucine utilization, 28 nmol x min-1 x g cells-1, is very high compared with normal cells, due to the high rate of lipid and protein synthesis. Its oxidation is similar to that of non-tumoural cells. 8. Sterols account for 80% of the lipids synthesized either from leucine or glucose.
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Tu SI, Lam E, Ramirez F, Marecek JF. Inhibition of the links between electron transfer and proton translocation in mitochondria. EUROPEAN JOURNAL OF BIOCHEMISTRY 1981; 113:391-6. [PMID: 6258918 DOI: 10.1111/j.1432-1033.1981.tb05078.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The mechanism by which proton extrusion is linked to electron transfer in mitochondria was investigated by means of the primary amine-specific reagent fluorescamine, and of compounds obtained from the reaction of fluorescamine with simple amines (e.g. benzylamine) and with the mycosamine-containing antibiotic amphotericin B. The effect of these 'modifiers' (i.e. fluorescamine transfer chain were assayed separately using specific inhibitors to block the action associated with the other site. Both types of modifiers inhibited the proton extrusion across the membrane to a significantly greater extent than the electron transfer process in both sites II and III. In contrast, the lactone derivative (or cyclic form) of the amine-fluorescamine compounds had no significant inhibitory effect on the proton extrusion and its associated electron transfer. These results are consistent with the hypothesis that the link between proton extrusion and electron transfer in mitochondria is indirect in nature. The results show that: (a) the links involved in sites II and III are identical or very similar in nature; (b) a covalent modification of primary amino groups in the inner membrane is not essential for the expression of these differential inhibitory effects; (c) specific structural features in the amine-fluorescamine compounds, and in the mitochondria-fluorescamine derivatives, are crucial for the expression of the inhibitory effects. Our results contradict the 'redox loop' model of Mitchell, and are compatible with the proton pump concept for the linked proton translocation in oxidative phosphorylation.
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The Electron Transport System and Hydrogenase of Paracoccus denitrificans. CURRENT TOPICS IN BIOENERGETICS 1981. [DOI: 10.1016/b978-0-12-152512-5.50009-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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On the location of the H+-extruding steps in site 2 of the mitochondrial electron transport chain. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)70367-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Villalobo A, Lehninger AL. Stoichiometry of H+ ejection coupled to electron transport through site 2 in ascites tumor mitochondria. Arch Biochem Biophys 1980; 205:210-6. [PMID: 7447477 DOI: 10.1016/0003-9861(80)90100-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Villalobo A, Lehninger AL. The phosphorylation potentials generated by respiring Ehrlich ascites tumor mitochondria. Arch Biochem Biophys 1980; 203:473-82. [PMID: 6250494 DOI: 10.1016/0003-9861(80)90201-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Lehninger AL, Reynafarje B, Alexandre A, Villalobo A. Respiration-coupled H+ ejection by mitochondria. Ann N Y Acad Sci 1980; 341:585-92. [PMID: 6249161 DOI: 10.1111/j.1749-6632.1980.tb47200.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Knowles AF, Kaplan NO. Oxidative phosphorylation and ATPase activities of human tumor mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA 1980; 590:170-81. [PMID: 6245684 DOI: 10.1016/0005-2728(80)90022-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Studies were carried out with intact mitochondria isolated from human astrocytoma, oat cell carcinoma and melanoma which were propagated in athymic mice. These human tumor mitochondria were capable of coupled oxidative phosphorylation. They also showed significant uncoupler-stimulated ATPase if defatted bovine serum albumin was included in the assay media. However, the uncoupler response curves were different and the magnitude of the ATPase activity was lower than could be obtained with mitochondria of a normal tissue, such as liver. Some of these characteristics were also exhibited by mitochondria from several animal hepatomas and Ehrlich ascites tumor. In the three tumors studied, mitochondria from oat cell carcinoma were more labile, whereas higher respiratory control ratios and greater stimulation of ATPase by uncouplers were obtained with melanoma mitochondria. The mitochondrial ATPase was not the major cellular ATPase in any of the three tumors. This was indicated by a low inhibition of the ATPase activity of tumor cell homogenates by oligomycin. A very large fraction of the cellular ATPase activities was recovered in the microsomal fractions.
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Villalobo A, Lehninger A. Inhibition of oxidative phosphorylation in ascites tumor mitochondria and cells by intramitochondrial Ca2+. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85914-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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24
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Alexandre A, Lehninger A. Stoichiometry of H+ translocation coupled to electron flow from succinate to cytochrome c in mitochondria. J Biol Chem 1979. [DOI: 10.1016/s0021-9258(19)86520-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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