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PubMed1978

The effects of carbodiimides on functions associated with the energy-conservation mechanism in beef heart sub-mitochondrial particles.

N,N'-di-n-propyl-, N,N'di-n-butyl-, N,N'-di-n-pentyl-, N,N'di-n-hexyl-, N,N'di-n-octoyl, N,N'-dibenzhydryl-, and N,N'-dibenzhydrylcarbodiimides were synthesized. They were all effective inhibitors (2 nmoles carbodiimide per milligram protein) of the ATP-driven reduction of NAD by succinate and the ATP-driven transhydrogenase activities catalyzed by beef heart submitochondrial particles (SMP). They had no effect on the nonenergy-linked transhydrogenase and stimulated the succinate-driven aerobic transhydrogenase activity of beef heart SMP. It was concluded that they exert their effects by reacting with the N,N'-dicyclohexylcarbodiimide-binding protein. Water-soluble carbodiimides were not effective inhibitors.

Adenosine Triphosphate↗
PubMedDate not supplied

Influence of metaphos on the structuro-functional organization of mitochondrial membranes.

It has been established by methods of spectrophotometry and spin probe that the organophosphorus pesticide metaphos, widely used in practice, is an inhibitor of NADH2 oxidase of the respiratory chain of the mitochondria and exerts an influence on the structural organization of the mitochondrial membrane. An effect of metaphos on the nature of the distribution and kinetics of NADH2-induced death of monoradical spin probes of various chemical structures was detected in a suspension of submitochondrial particles obtained from beef heart.

Animals↗
PubMedDate not supplied

[Changes in the mitochondrial ATPase activity of liver cells after X-ray irradiation].

24 h following total-body X-irradiation of rats with a dose of 7 Gy the growth of the ATPase activity diminished, with the addition of bicarbonate, by 2 times in the preparations of mitochondria and submitochondrial particles, and by 1.5 times, in preparations of a soluble enzyme. No changes were noted in the electrophoretic motility of soluble ATPase.

Adenosine Triphosphatases↗
PubMed1982

[Effect of ionol-type antioxidants on the energetics of liver mitochondria].

An injection of ionol-type antioxidants stimulates fast oxidation of extramitochondrial NADH in isolated liver mitochondria via an external pathway, which is sensitive to cyanide and resistant to amital and antimycin A. This activation is accompanied by a decrease in cytochrome a and cytochrome (c + C1) levels in liver homogenate. Part of the cytochrome c pool can be removed by washing the antioxidant-treated mitochondria. It is assumed that the injection of the antioxidants leads to desorption of the cytochrome c bound to the inner membrane into the intermembrane space of mitochondria. This cytochrome acts as a linking agent between NADH cytochrome c reductase of the outer mitochondrial membrane and cytochrome c oxidase of the inner membrane. The Li-derivative of ionol (5 x 10(-4) and 10(-3) M) decreases the transmembrane potential of the submitochondrial particles from bovine heart by 15-20%.

Animals↗
PubMed1981

Occurrence of proteins immunoreactive with anti-coupling factor B in phosphorylating membrane preparations.

Coupling factor B has been isolated from beef heart mitochondria, apparently in multiple forms which differ in molecular weight and specific activity. Since it has no known intrinsic catalytic activity, detection and quantitation have been based upon the factor B-dependent stimulation of ATP-linked activities in factor B-deficient sub-mitochondrial particles. This communication reports the development of a reliable and more universally applicable enzyme-linked immunosorbent assay (ELISA) for detection and quantitation of factor B in soluble or membranous preparations. The assay requires nanoliter volumes of rabbit antiserum raised against purified factor B and will detect nanogram amounts of the coupling factor. Analysis of beef heart submitochondrial particles using a competitive binding ELISA indicated a factor B content of 0.27 nmol/mg protein, making factor B stoichiometric with F1 (0.3--0.6 nmol/mg). Furthermore, application of the factor B ELISA has indicated the presence of material cross-reacting with the beef heart factor B-antiserum in phosphorylating membranes from chloroplasts, Escherichia coli, Paracoccus denitrificans and the thermophilic bacterium, PS3. Negative results were obtained with mitochondria and microsomes from rat liver, purple membranes from Halobium halobacterium and sarcoplasmic reticulum from rabbit skeletal muscle.

Animals↗
PubMed1980

Carbon monoxide-reacting haemoproteins in the mitochondrial fraction of Acanthamoeba castellanii.

1. Room-temperature (18 degrees C) CO difference spectra of mitochondrial fractions from the amoeba Acanthamoeba castellanii reveal the presence of at least four CO-reacting haemoproteins. As well as cytochrome a3, other components reacting with CO are: (i) a c-type cytochrome; (ii) a b-type cytochrome; and (iii) another a-type cytochrome. 2. The same components can be identified in low-temperature photodissociation experiments with intact cells or mitochondria. 3. The time of exposure to CO and the nature of the reductant are both important in identifying all the components present, in that the b-type cytochrome is more readily distinguished after longer exposure to CO and more of the c-type cytochrome is detectable when NADH is the reductant 4. Treatment of mitochondria with ultrasound releases two components, identifiable in low-temperature difference spectra as a c-type and a b-type cytochrome; only the latter appears to have any reaction with CO, and the CO-reacting c-type cytochrome is retained in submitochondrial particles. 5. The complexity of the CO-reacting haemoproteins in this organism is compared with the simpler systems found in other eukaryotic organisms.

Amoeba↗
PubMed1983

Regulation of the synthesis and hydrolysis of ATP by mitochondrial ATPase. Role of the natural ATPase inhibitor protein.

The action of the natural ATPase inhibitor protein of Pullman and Monroy (Pullman, M. E., and Monroy, G. C. (1963) J. Biol. Chem. 238, 3762-3769) on the mechanisms of energy conservation of heart mitochondria has been explored. The synthesis and hydrolysis of ATP and the Pi-ATP exchange reaction were studied in submitochondrial particles that possess the ATPase-inhibitor protein complex in two distinguishable states. In addition to their different rates of hydrolysis, the two states of the complex have been identified from their different accessibility to antibodies directed against the inhibitor protein, and from the different action of antibodies and trypsin on the ATPase activity of the two types of particles studied. The steady state rates of hydrolysis and of the Pi-ATP exchange reaction of the particles are determined by the state in which the ATPase-inhibitor complex exists. Apparently by modifying the rate of one of the steps involved in the catalytic reaction of the ATPase, the inhibitor protein determines the extent to which the enzyme is able to catalyze ATP hydrolysis and the Pi-ATP exchange reaction. This action of the inhibitor protein also reflects the rate at which the particles carry out oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1979

[Role of planar cobalt chelate complexes as shunting agents in the electron transport chain of mitochondria].

It was shown that planar cobalt chelate complexes catalyze oxidation of NADH and hexahydroubiquinole Q4H2 by air oxygen. The most active agent--perchlorate of the cobalt complex 1, 2, 3, 7, 8, 12, 13, 17, 18, 19-decamethyloctadehydrocorrin--is capable of shunting the electron transfer chain of rat liver mitochondria and beef heart submitochondrial particles, catalyzing electron transfer from CoQ directly to the oxygen.

Animals↗
PubMed1979

An analysis of the polypeptide composition of bovine heart mitochondrial NADH-ubiquinone oxidoreductase by two-dimensional polyacrylamide-gel electrophoresis.

Purified preparations of Complex I (NADH-ubiquinone oxidoreductase) from bovine heart mitochondria may be resolved into 26 polypeptides by two-dimensional analysis combining isoelectric focusing and polyacrylamide-gel electrophoresis in sodium dodecyl sulphate. Similar analyses of the fragments obtained from chaotropic resolution of the enzyme show that each of these fragments contains a distinct and non-overlapping set of polypeptides. Evidence that the polypeptides seen in the intact enzyme are true constituents comes from analyses of immunoprecipitates obtained by allowing Complex I or solubilized submitochondrial particles to react with antisera directed against the whole enzyme and a subfragment of the enzyme.

Animals↗
PubMed1981

Inhibition of the mitochondrial nicotinamide nucleotide transhydrogenase by dicyclohexylcarbodiimide and diethylpyrocarbonate.

The mitochondrial nicotinamide nucleotide transhydrogenase enzyme (EC 1.6.1.1) is inhibited by treatment with dicyclohexylcarbodiimide or diethylpyrocarbonate. Both inhibitions are pseudo first order with respect to incubation time, and both reaction orders with respect to inhibitor concentration are close to unit, indicating that in each case inhibition results from the binding of one inhibitor molecule per active unit of the transhydrogenase enzyme. In the presence of either inhibitor, both the energy-linked and the nonenergy-linked transhydrogenation reactions are inhibited at about the same rate. The water-soluble carbodiimide, N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide, showed no inhibition, however, NAD(H) and reduced or oxidized 3-acetylpyridine adenine dinucleotide protected the enzyme against inhibition by dicyclohexylcarbodiimide, while NADP (but not NADPH) appeared to increase the rate of inhibition. Substrates did not protect the enzyme against inhibition by diethylpyrocarbonate. [14C]dicyclohexylcarbodiimide labeled the transhydrogenase enzyme in submitochondrial particles. Treatment of labeled particles with trypsin resulted in fragmentation of the transhydrogenase enzyme and loss of a labeled polypeptide of Mr = approximately 100,000 as determined by polyacrylamide gel electrophoresis.

Animals↗
PubMed1982

Effects of Q metabolites and related compounds on mitochondrial succinate and NADH oxidase systems.

The effects of Q metabolites (Q acid-I, Q acid-II) and related compounds (dihydro Q acid-I, dehydro Q acid-II, QS-n, and their esters) on mitochondrial succinate and NADH oxidase systems were investigated. The activity restoring succinate oxidation in acetone-treated beef heart mitochondria was found to decrease with descending order of carbon number (n) of the side chain of the Q metabolites; activity was restored with Q acid-I (n = 7) to one-third as much as that with Q-7 and Q-10, but Q acid-II (n = 5) did not restore any activity. Of the related compounds with a carboxyalkyl group (QS-n), QS-16-QS-18 (n = 16-18) were found to be most active, and their activities were also correlated with n. The relationship between the restoration of activity and the partition coefficient was considered. NADH oxidation in pentane-treated beef heart submitochondrial particles could be restored with esters of low molecular weight quinones to the same extent as with Q-10, but not with the metabolites.

Animals↗
PubMed1981

Effect of ubiquinone extraction on ubiquinol-1 oxidase activity in beef heart mitochondria.

Extraction of endogenous ubiquinone with different methods does not influence ubiquinol oxidase activity in lyophilized mitochondria in terms of KM, although a decrease of Vmax is sometimes observed. Experiments with submitochondrial particles from a UQ-deficient mutant of S. cerevisiae confirm the results with UQ-depleted mitochondria and support the idea that endogenous ubiquinone is not required for the oxidation of exogenous ubiquinols by complex III.

Animals↗
PubMed2002

Factor B is essential for ATP synthesis by mitochondria.

Factor B is a water-soluble protein, which is required for the coupled activity of the mitochondrial ATP synthase complex. Specific removal of factor B from well-coupled bovine heart submitochondrial particles (SMP) results in uncoupling and the loss of ATP-driven membrane potential formation and reverse electron transfer from succinate to NAD. Addition of recombinant human factor B (molecular mass 20,341 Da) to factor B-depleted SMP (AE-SMP) restores these properties [G.I. Belogrudov, and Y. Hatefi, (2002) J. Biol. Chem. 277, 6097-6103]. This paper shows that extraction and purification of ATP synthase complex (complex V) from bovine heart mitochondria results in extensive loss of factor B. Addition of recombinant human factor B to AE-SMP completely restores the lost oxidative phosphorylation and ATP-32P(i) exchange activities of the particles and increases the ATP-32P(i) exchange activity of complex V by 2.5-fold. These results further indicate that factor B is an essential component of the mammalian ATP synthase complex.

Adenosine Triphosphatases↗
PubMed1985

Adenine nucleotide and phosphate transport systems of mitochondria. Relative location of sulfhydryl groups based on the use of the novel fluorescent probe eosin-5-maleimide.

Eosin-5-maleimide is impermeable to the inner mitochondrial membrane, exhibiting essentially no reactivity with matrix glutathione or with beta-hydroxybutyrate dehydrogenase located on the matrix surface of the inner membrane. In intact mitochondria, eosin-5-maleimide is unreactive with the ADP/ATP antiporter even under conditions which promote maximal labeling by N-[3H]ethylmaleimide (i.e., ADP present). However, eosin-5-maleimide readily labels the ADP/ATP antiporter in "inverted" inner membrane vesicles even in the presence of N-ethylmaleimide. Labeling is prevented if the vesicles are prepared from mitochondria pretreated with carboxyatractyloside. In contrast to the ADP/ATP antiporter, essential sulfhydryl groups of the Pi/H+ symporter are accessible to eosin-5-maleimide in intact mitochondria with optimal inhibition of phosphate transport being observed at 25 degrees C. Eosin-5-maleimide also prevents labeling of the Pi/H+ symporter by N-[3H]ethylmaleimide. These results show that essential sulfhydryl groups of the ADP/ATP antiporter and the Pi/H+ symporter have differing reactivities and locations in functionally intact mitochondria. With respect to eosin-5-maleimide, sulfhydryl groups of the ADP/ATP carrier occur in two distinct classes, both of which are inaccessible in intact mitochondria. Only one class, depending on conditions, can be exposed in submitochondrial particles. In contrast, sulfhydryl group(s) of the Pi/H+ symporter behave as a single reactive class which is readily accessible in mitochondria at 25 degrees C.

Animals↗
PubMed1990

Slow active/inactive transition of the mitochondrial NADH-ubiquinone reductase.

NADH-ubiquinone reductase of bovine heart submitochondrial particles as prepared is unable to catalyze either the direct or reverse electron transfer from NADH to ubiquinone. The deactivated state of the enzyme in coupled particles was revealed as: (i) the absence of the rotenone-sensitive, delta mu H(+)-dependent succinate-ferricyanide reductase activity; (ii) a prominent lag in the aerobic succinate-supported, delta mu H(+)-dependent NAD+ reduction; and (iii) a lag in the rotenone-sensitive NADH-ubiquinone reductase or NADH oxidase activities. Being inactive as NADH-ubiquinone reductase (direct or reverse), the enzyme is fully active as rotenone-insensitive NADH-ferricyanide reductase. The enzyme can be activated by preincubation with substrates (NADH or NADPH) only under the conditions where the turnover of the NADH-ubiquinone reductase reaction (but not in the NADH-ferricyanide reductase) occurs. Partial activation of the enzyme was observed when the particles were preincubated with rotenone. Neither NADH under the conditions when the ubiquinone pool was reduced nor succinate plus delta mu H+ or dithionite were able to activate the enzyme. Once activated, the enzyme remains in the active state for quite a long time (more than 5 h at 0 degree C). The deactivation rate is extremely temperature-dependent, being insensitive to NAD+, ferricyanide or succinate. A comparison of the enzyme activation/deactivation kinetics showed that the same mechanism is involved in the slow activation of the direct and reverse electron transfer from NADH to ubiquinone. Activated particles catalyze the aerobic delta mu H(+)-dependent succinate-supported reverse electron transfer in the absence of ATP at a rate comparable with that of NADH-ubiquinone reductase.

Animals↗
PubMed1989

The interaction of the cardioprotective agent ICRF-187 [+)-1,2-bis(3,5-dioxopiperazinyl-1-yL)propane); its hydrolysis product (ICRF-198); and other chelating agents with the Fe(III) and Cu(II) complexes of adriamycin.

Membrane-permeable ICRF-187 [+]-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane) has shown promise as a cardioprotective agent against adriamycin-induced cardiotoxicity. ICRF-187 may act through its rings-opened hydrolysis product (ICRF-198), which has an EDTA-type structure and, likewise, strongly binds metal ions. The reactions of these compounds with Fe3+-adriamycin and Cu2+-adriamycin complexes were examined. ICRF-198 quickly and completely removed both Fe3+ and Cu2+ from their complexes with adriamycin. ICRF-187 also reacted directly, but more slowly, with Fe3+-adriamycin to remove Fe3+ from the complex. This reaction was first order in ICRF-187 and Fe3+-adriamycin and yielded a second order rate constant of 123 M-1 min-1. Metal ion-complex promoted hydrolysis may thus contribute to the in vivo hydrolysis of ICRF-187 to its metal ion-chelating active rings-opened form. Both ICRF-187 and ICRF-198 were very effective in preventing the Fe3+-adriamycin induced inactivation of the cytochrome c oxidase activity of submitochondrial particles. A number of other chelating agents (desferal; penicillamine; DTPA; EDTA; TPEN; bathophenanthroline sulfonic acid; 2,2'-bipyridine; 1.10-phenanthroline, glutathione and 2-mercaptoethanol) were also examined for their ability to remove Fe3+ and Cu2+ from their complexes with adriamycin.

Cardiotonic Agents↗
PubMed1980

The non-catalytic nucleotide-binding site of mitochondrial ATPase is localised on the alpha-subunit(s) of factor F1.

The incubation of isolated factor F1 with the di-aldehyde derivative of ADP (oxADP) which is formed as a result of ADP treatment by periodate, causes the covalent binding of 0.9--1 molecules of the oxADP with a molecule of the enzyme. This modification of factor F1 is not accompanied by any changes in the ATPase activity of the enzyme. The modification of factor F1 is preceded by the reversible binding of oxADP with the enzyme with a Kd of 80 micro M. ADP partly prevents factor F1 from modification by oxADP. The electrophoresis of modified factor F1 in polyacrylamide gel in the presence of sodium dodecyl sulphate showed that oxADP binds with the alpha-subunit(s) of factor F1. When submitochondrial particles are incubated with [3H]oxADP, the main part of the radioactive label may be discovered in the polypeptide with a molecular weight of some 30 000 which is probably the adenine nucleotides' translocase. The isolation of factor F1 from particles preincubated with [3H]oxADP showed that the membrane-bound factor F1 covalently binds 0.2--0.3 mol of oxADP per mol of enzyme. Here again, all the oxADP is bound with the alpha subunit(s) of factor F1. The modification of membrane-bound factor F1 by oxADP is accompanied by the partial inhibition of the particles' ATPase activity. The results obtained testify to the fact that the non-catalytic site of mitochondrial ATP ase located on the alpha-subunit(s) of factor F1 may participate in the mechanism of ATP hydrolysis by membrane-bound ATPase.

Adenosine Triphosphatases↗