Succinoxidase System Research Articles

Pyridine Nucleotide‐Linked Lactate Dehydrogenase of Tetrahymena: Evidence for D‐ and L‐Enzymes in the Mitochondria

An NAD linked lactate dehydrogenase (LDH) in a crude mitochondrial fraction obtained from Tetrahymena homogenates was previously reported by this laboratory. This fraction contains the NADH and succinate oxidase system as well as the mitochondrial cytochromes and carries out oxidative phosphorylation. The preparation catalyzes the oxidation of D- and L-lactate linked only to certain analogues of NAD; it has not been possible to demonstrate NAD-dependent D- or L-lactate oxidation nor is there any evidence that either of these enzymes is a flavoprotein as indicated by their inability to reduce directly certain artificial electron acceptors. A lactate racemase is not present.

Paragonimus westermani possesses aerobic and anaerobic mitochondria in different tissues, adapting to fluctuating oxygen tension in microaerobic habitats

We previously showed that adult Paragonimus westermani, the causative agent of paragonimiasis and whose habitat is the host lung, possesses both aerobic and anaerobic respiratory chains, i.e., cyanide-sensitive succinate oxidase and NADH-fumarate reductase systems, in isolated mitochondria (Takamiya et al., 1994). This finding raises the intriguing question as to whether adult Paragonimus worms possess two different populations of mitochondria, one having an aerobic succinate oxidase system and the other an anaerobic fumarate reductase system, or whether the worms possess a single population of mitochondria possessing both respiratory chains (i.e., mixed-functional mitochondria). Staining of trematode tissues for cytochrome c oxidase activity showed three types of mitochondrial populations: small, strongly stained mitochondria with many cristae, localised in the tegument and tegumental cells; and two larger parenchymal cell mitochondria, one with developed cristae and the other with few cristae. The tegumental and parenchymal mitochondria could be separated by isopycnic density-gradient centrifugation and showed different morphological characteristics and respiratory activities, with low-density tegumental mitochondria having cytochrome c oxidase activity and high-density parenchymal mitochondria having fumarate reductase activity. These results indicate that Paragonimus worms possess three different populations of mitochondria, which are distributed throughout trematode tissues and function facultatively, rather than having mixed-functional mitochondria.

The effect of artichoke (Cynara scolymus L.) extract on respiratory chain system activity in rat liver mitochondria

The effect of artichoke extract on mitochondrial respiratory chain (MRC) activity in isolated rat liver mitochondria (including reaction kinetics) was studied. The effect of the extract on the activity of isolated cytochrome oxidase was also studied. Extract in the range of 0.68-2.72 microg/ml demonstrated potent and concentration-dependent inhibitory activity. Concentrations > or =5.4 microg/ml entirely inhibited MRC activity. The succinate oxidase system (MRC complexes II-IV) was the most potently inhibited, its activity at an extract concentration of 1.36 microg/ml being reduced by 63.3% compared with the control (p < 0.05). The results suggest a complex inhibitory mechanism of the extract. Inhibition of the succinate oxidase system was competitive (K(i) = 0.23 microg/ml), whereas isolated cytochrome oxidase was inhibited noncompetitively (K(i) = 126 microg/ml). The results of this study suggest that the salubrious effects of artichoke extracts may rely in part on the effects of their active compounds on the activity of the mitochondrial respiratory chain system.

Inhibitory effect of t-butyl hydroperoxide on mitochondrial oxidative phosphorylation in isolated rat hepatocytes

Using high-resolution oxygraphy, we tested the changes of various parameters characterizing the mitochondrial energy provision system that were induced by peroxidative damage. In the presence of succinate as respiratory substrate, 3 mM t-butyl hydroperoxide increased respiration in the absence of ADP, which indicated partial uncoupling of oxidative phosphorylation. Low activity of coupled respiration was still maintained as indicated by the ADP-activated and oligomycin-inhibited respiration. However, during the incubation the phosphorylative capacity decreased as indicated by the continuous decrease of the mitochondrial membrane potential. Under these experimental conditions the maximum capacity of the succinate oxidase system was inhibited by 50% in comparison with values obtained in the absence of t-butyl hydroperoxide. Our data thus indicate that the oxygraphic evaluation of mitochondrial function represents a useful tool for evaluation of changes participating in peroxidative damage of cell energy metabolism.

Properties of yeast Saccharomyces cerevisiae plasma membrane dicarboxylate transporter

Transport of succinate into Saccharomyces cerevisiae cells was determined using the endogenous coupled mitochondrial succinate oxidase system. The dependence of succinate oxidation rate on the substrate concentration was a curve with saturation. At neutral pH the K(m) value of the mitochondrial "succinate oxidase" was fivefold less than that of the cellular "succinate oxidase". O-Palmitoyl-L-malate, not penetrating across the plasma membrane, completely inhibited cell respiration in the presence of succinate but not glucose or pyruvate. The linear inhibition in Dixon plots indicates that the rate of succinate oxidation is limited by its transport across the plasmalemma. O-Palmitoyl-L-malate and L-malate were competitive inhibitors (the K(i) values were 6.6 +/- 1.3 microM and 17.5 +/- 1.1 mM, respectively). The rate of succinate transport was also competitively inhibited by the malonate derivative 2-undecyl malonate (K(i) = 7.8 +/- 1.2 microM) but not phosphate. Succinate transport across the plasma membrane of S. cerevisiae is not coupled with proton transport, but sodium ions are necessary. The plasma membrane of S. cerevisiae is established to have a carrier catalyzing the transport of dicarboxylates (succinate and possibly L-malate and malonate).

Effect of doxorubicin on oxidative phosphorylation in brain mitochondria

Inin vitro experiments, antineoplastic anthracycline antibiotic doxorubicine caused deenergization of rat brain mitochondria due to oxidation-phosphorylation uncoupling and inhibition of succinate oxidase system. Reduced production and oxidation of succinic acid is the most early effect of doxorubicin on mitochondrial oxidation.

Effect of arylthiolated 2,3-dimethoxy-1,4-benzoquinones on respiratory activity and lipid peroxidation in bovine heart mitochondria.

A series of arylthiolated 2,3-dimethoxy-1,4-benzoquinones was synthesized and tested for the effect on the respiratory system and the lipid peroxidation in bovine heart mitochondria (BHM). These quinones showed intense inhibitory activities on the respiratory system in BHM. Their inhibitory activity in the succinate oxidase system was greater than that in the NADH oxidase system. No difference between the difference spectra, with and without these quinones, of the reduced minus oxidized forms of cytochromes (cyt.) suggested that these quinones inhibit at the site after cyt. a+a3 in the respiratory chain. Moreover, these quinones were as efficient as exogenous ubiquinone-10 (UQ-10) for the inhibition of lipid peroxidation. 5- And 5,6-di-arylthio groups on the quinone ring were found to be favorable for inhibition of the respiratory system and lipid peroxidation. Our results suggest that arylthiolated 2,3-dimethoxy-1,4-benzoquinones act as antioxidants by increasing the amount of endogenous reduced UQ-10 in BHM.

Respiratory Chain of the Lung Fluke Paragonimus westermani - Facultative Anaerobic Mitochondria

The respiratory chain of adult Paragonimus westermani, a lung fluke, was characterized in isolated mitochondria. The fluke mitochondria exhibited cyanide- and antimycin A-sensitive succinate oxidase activity at a rate of 16.8 nmol O 2 min −1 mg −1 protein. The succinate oxidation was shown to be stimulated by ADP and linked to the formation of membrane potential. The specific activities of oxidoreductases composing the succinate oxidase system, i.e., succinate-ubiquinone and succinate-cytochrome c oxidoreductase (complex II and complex II-III, respectively) and cytochrome c oxidase (complex IV), were compared in mitochondria from adult Paragonimus, bovine heart (an aerobic tissue), and muscle of adult Ascaris suum which possesses an anaerobic respiratory chain. The activity values of complex II-III and complex IV were high, middle, and low for bovine heart, Paragonimus, and A. suum, respectively, whereas the activity of complex II was comparable among the three sources. The cytochrome contents of Paragonimus mitochondria as determined by difference absorption spectrophotometry ranged between those in Ascaris and bovine mitochondria for types c and aa 3 cytochromes. Paragonimus mitochondria exhibited a high activity of NADH-fumarate reductase; the specific activity was about 18-fold higher in fluke submitochondria than in bovine heart submitochondria. Quinone analysis by HPLC and mass spectrometry showed that the fluke mitochondria contain both rhodoquinone-10 and ubiquinone-10 at concentrations of 0.572 and 0.321 nmol mg −1 mitochondrial protein, respectively. These data clearly show that mitochondria from adult P. westermani, unlike adult Ascaris mitochondria, possess both cyanide-sensitive succinate oxidase and NADH-fumarate reductase systems, indicating that the fluke mitochondria are facultatively anaerobic.

Altered kinetic properties of liver mitochondrial membrane-bound enzyme activities following paracetamol hepatotoxicity in the rat

The effects of treatment with subtoxic (375 mg/kg) and toxic (750 mg/kg) doses of paracetamol on NADH oxidase, succinoxidase and Mg2+-ATPase activities in rat liver submitochondrial particles were examined. In the NADH oxidase system, treatment with subtoxic doses of paracetamol resulted in a 37% increase in activation energy in the high temperature range (E1) while the phase transition temperature (Tt) for this system decreased by 9‡C. Subtoxic doses caused a 43% decrease in E1. For the succinoxidase system, Tt decreased by 2.4 to 3.4‡C after paracetamol administration. E2 increased by 42% only in the subtoxic-treatment group while E1 remained unaltered in both paracetamol-treated groups. For the Mg2+-ATPase system, subtoxic doses of paracetamol treatment did not change the values of E1 E2 and Tt whereas toxic dose treatment resulted in a 29% decrease in E2 with a concomitant increase in Tt by 2.4‡C without any change in the value of E1 The results thus suggest that treatment with toxic and subtoxic doses of paracetamol results in possible differential alterations in the membrane lipid milieu.

Inhibition of mitochondrial respiratory chain by arylthiolated 2,3-ethylenedioxy-1,4-benzoquinones.

A series of arylthiolated 2,3-ethylenedioxy-1,4-benzoquinones as a coenzyme Q (CoQ) antagonist was tested for inhibition of succinate oxidase and reduced nicotinamide adenine dinucleotide (NADH) oxidase systems in the mitochondrial respiratory chain. The following characteristics were revealed: (1) 2,3-ethylenedioxy, 5-arylthio and 5,6-diarylthio groups were confirmed to be favorable for inhibition of both systems; (2) these analogs were more effective in the succinate oxidase system than in the NADH oxidase system; (3) 4' substituents on the benzene side ring had little effect on inhibitory activity; (4) the acting sites of these analogs had no strict stereospecificity. The reduced minus oxidized difference spectra revealed that these analogs inhibited the succinate oxidase system at the site between succinate and CoQ, and the NADH oxidase system at the site after cytochrome a + a3, suggesting these analogs might act as antagonists of CoQ in the succinate oxidase system. However, 5-(4'-nitrophenylthio)-2,3-ethylenedioxy-1,4-benzoquinone (If) strongly inhibited only the succinate oxidase system at the site after cytochrome a + a3.

Altered kinetic properties of rat heart mitochondrial enzymes following experimental-thyrotoxicosis

Effects of T 3- and T4-induced thyrotoxicosis on temperature-dependent Arrhenius kinetics of succinate oxidase and Mg 2+ - and Mg2+ + 2,4-dinitrophenol- dependent ATPase activities in rat heart mitochondria were examined, For succinate oxidase system, treatment with T3 and T4 caused increase in the energy of activation in high temperature range in a dose-dependent manner. For low temperature range, increase in energy of activation was apparent only with higher doses of the hormones; with low doses a small but reproducible decrease was evinced. The phase transition temperature decreased significantly under these conditions. For the Mg 2+ - and Mg 2+ +2,4-dintro- phenol-dependent-ATPase activities, the activation energy values in high temperature range decreased in general. Activation energy values in low temperature range recorded a generalized increase in the Mg 2+ -ATPase enzyme system while the value did not change significantly for the Mg 2+ + 2,4-dinitrophenol-ATPase; phase transition temperature registered a small but reproducible decrease under these conditions. The results are suggestive of increased membrane fluidization possibly through increased proportion of unsaturated fatty acids. The differential effects seen for succinate oxidase and ATPase systems are consistent with different lipid protein domains of these enzyme systems.

Myeloperoxidase-mediated damage to the succinate oxidase system of Escherichia coli. Evidence for selective inactivation of the dehydrogenase component.

Myeloperoxidase, a granule-associated enzyme of neutrophils and monocytes, combines with H2O2 and chloride to form a potent microbicidal system that contributes to phagocyte antimicrobial activity. The nature of the lesion or lesions induced by the myeloperoxidase system which are responsible for the loss of microbial replicative activity (viability) remains unknown. Using Escherichia coli grown to late log or stationary phase under conditions of low aeration with succinate as the sole carbon source, we found that myeloperoxidase-induced loss of microbial viability could be correlated with a decrease in succinate-dependent respiration (succinate oxidase activity). Succinate dehydrogenase activity fell rapidly to undetectable levels during incubation with the myeloperoxidase system, suggesting that damage to the dehydrogenase was a major factor in the loss of oxidase activity. Other components of the succinate oxidase system were resistant to the actions of myeloperoxidase. The ubiquinone-8 and cytochrome components of the respiratory chain remained nearly constant in amount despite reduction of respiration to undetectable levels. However, as expected from the loss of succinate dehydrogenase activity, succinate-ubiquinone reductase and succinate-cytochrome reductase activities were markedly impaired. We propose that the loss of E. coli viability induced by the myeloperoxidase-H2O2-chloride system is due in part to the loss of electron transport function consequent to the oxidation of critical catalytic centers in susceptible dehydrogenases.

Synthesis and biological activities of 2,3-dimethyl-1,4-benzoquinones having alkylthio and arylthio side chains.

New 2, 3-dimethyl-1, 4-benzoquinones having an alkylthio or arylthio side chain at the 5-position and two alkylthio side chains at the 5-and 6-position were synthesized as possible antimetabolites of coenzyme Q. These compounds were tested for inhibition of coenzyme Q in mitochondrial succinoxidase and reduced nicotinamide adenine dinucleotide (NADH) -oxidase systems, and were found to show greater inhibition of the NADH-oxidase system than of the succinoxidase system. 5, 6-Di-octylthio-2, 3-dimethyl-1, 4-benzoquinone showed greater inhibitory activities than 5-alkylthio-2, 3-dimethyl-1, 4-benzoquinones. 5-Arylthio-2, 3-dimethyl-1, 4-benzoquinones showed potent inhibitory activities towards both enzyme systems.

Temperature adaptation of biological membranes. Compensation of the molar activity of cytochrome c oxidase in the mitochondrial energy-transducing membrane during thermal acclimation of the carp ( cyprinus carpio L.)

The acclimation temperature of carp does not affect the amount of cytochrome c oxidase per mg mitochondrial protein as revealed from the reduced-minus-oxidized difference spectra of red muscle mitochondria from cold- and warm-acclimated carp. There are no differences between cold- and warm-acclimated fish in the substrate binding properties of the enzyme as judged from the K m values for cytochrome c at 30°C ( 3.34 ± 0.33 μ M , acclimation temperature 10°C and 3.55 ± 0.31 μ M , acclimation temperature 30°C). The molar activities of the enzyme, however, differ for both acclimation temperatures: when intercalated in the 10°C-acclimated mitochondrial membrane, the enzyme can catalyze the oxidation of 117.6 ± 17.2 mol ferrocytochrome c/s per mole heme a as compared with 85.6 ± 17.2 in the 30°C-acclimated membrane (experimental temperature 30°C). Correspondingly, higher specific activities of the succinate oxidase system are observed in mitochondria from cold-acclimated carp as compared with those obtained from warm-acclimated carp. The results indicate that cold acclimation of the eurythermic carp is accompanied by a partial compensation of the acute effect of decreasing temperature on the activity of cytochrome c oxidase in red muscle mitochondria. Based on the temperature-induced lipid adaptation reported for carp red muscle mitochondria (Wodtke, E. (1980) Biochim. Biophys. Acta 640, 698–709), it is concluded that during thermal acclimation the molar activity of cytochrome c oxidase is controlled by viscotropic regulation. The results fit to the conception that cardiolipin constitutes a lipid shell (annulus) surrounding the oxidase within the native membrane, but that it is the bilayer fluidity and not the annular fluidity which determines the activity of cytochrome c oxidase.

Identification of the BAL-labile factor.

One of us has previously reported that treatment of the Keilin and Hartree heart-muscle preparation with 2,3-dimercaptopropanol (BAL), in the presence of air, leads to the complete inactivation of the succinate oxidase system with little if any effect on the activities of succinate dehydrogenase (until more than half the BAL was oxidized) or cytochrome c oxidase. The inactivation of the complete succinate oxidase system requires the oxidation of BAL by air in the presence of the enzyme. It is not caused by H2O2 or BAL disulphides produced during the oxidation of BAL. Spectroscopic studies identified the block as lying between cytochromes b and c. It was suggested that a BAL-labile factor is present which transfers electrons from cytochrome b to cytochrome c and which is destroyed by coupled oxidation with BAL. The factor is also required for NADH oxidation. Subsequent work showed it is not identical with cytochrome c1 (ref. 4), myoglobin present in the preparation or the antimycin-binding site. We report here that this factor is identical to the iron-sulphur protein in the central portion of the respiratory chain first identified by Rieske.

Semi-synthetic analogs of cytochrome [formula omitted] Substitutions for methionine at position 80

Derivatives of cytochrome c having S- methyl cysteine and ethionine substituted for methionine residue 80 have been synthesized in order to study the effects of structural perturbations near the heme on the biological function of cytochrome c. The ethionine derivative has 96% as much activity as native cytochrome c in the succinate oxidase system, whereas the S- methyl cysteine analog is totally inactive.

Toxicology of various pesticides and their decomposition products on mitochondrial electron transport.

The effect of various pesticides and derivatives on mitochondrial electron transport systems was assessed. DDT, DDE, TDE, Kelthane, chlorobenzilate, chloropropylate and Acarol were found to be inhibitory towards both heavy beef heart mitochondrial (HBHM) NADH-oxidase and succinoxidase enzyme systems. Dichlorobenzophenone and p-chlorophenol were less inhibitory towards the HBHM NADH-oxidase and did not inhibit the succinoxidase enzyme system. DDA did not inhibit either of the electron transport systems. Carbaryl was not inhibitory towards both HBHM oxidase systems, whereas its degradative product dihydroxynaphthalene was inhibitory at the same concentration. Furadan, Matacil, Baygon and Dimetilan were only slightly inhibitory towards themitochondrial NADH-oxidase system and did not inhibit the succinoxidase system. Zectran was inhibitory towards the NADH-oxidase system and was not inhibitory towards the succinoxidase system. DDT, DDE and TDE, dihydroxynaphthalene and 1-naphthol inhibited the NADH-oxidase enzyme system onthe substrate side of cytochrome c, whereas Kelthane inhibited on the oxygen side.

Effect of the non-ionic detergent triton X-100 on mitochondrial swelling

1. 1. 10 −4 M Triton X-100 does not promote by itself mitochondrial swelling, and it has no effect on energy-dependent succinate induced, or on peroxyde-dependent ascorbate induced swelling and lysis. 2. 2. 10 −4 M Triton X-100 induces swelling at a slow rate in the presence of 10 −3M EDTA, and decreases the swelling effect of 10 −2 M Ca 2+. This can be interpreted in terms of a nonspecific increase in mitochondrial membrane permeability due to the detergent. 3. 3. 0.012 M CN − inhibits succinate induced mitochondrial swelling, but 10 −4M Triton X-100 reverses this inhibition. In this case, the surfactant may act by inducing a conformational change, or by selectively solubilizing an inhibitory subunit of the succinoxidase system.

Semi-synthetic analogs of cytochrome [formula omitted] at positions 67 and 74

New semi-synthetic peptide analogs of horse heart cytochrome c have been prepared by replacing tyrosine at position 67 by phenylalanine and L-parafluorophenylalanine. The former has 56% biological activity in the succinate oxidase system whereas the parafluorophenylalanine analog is totally inactive. The tyrosine at position 74 has also been replaced by leucine. It shows a high level of biological activity (58%), which demonstrates that the presence of an aromatic residue at this position is not required for electron transfer.

Semisynthetic analogs of cytochrome c reconstructed from natural and synthetic peptides

A biologically active semisynthetic hybrid of horse heart cytochrome c has been prepared by combining the heme peptide 1 through 65 (HP 1–65), prepared by CNBr cleavage of natural cytochrome c, with a semisynthetic peptide corresponding to positions 66 through 104. A fully protected synthetic peptide 66–79 was prepared by a modified solid phase peptide synthesis procedure and was converted to its N-hydroxysuccinimide ester. A peptide corresponding to residues 81–104 of cytochrome c was also isolated from the CNBr cleavage mixture and its ϵ-amino groups and tyrosyl hydroxyl group were protected selectively with the t-butyloxycarbonyl group. This partially protected peptide was reacted with t-butyloxtcarbonyl methionine N-hydroxysuccinimide ester to give a derivative having methionine at position 80. This product was deprotected, purified and then t-butyloxycarbonyl groups were again introduced specifically on the ϵ-amino groups to give the peptide, Boc(Lys,Tyr)80–104. A semisynthetic peptide corresponding to residues 66 through 104 of cytochrome c was prepared by condensing the synthetic peptide 66–79 N-hydroxysuccinimide ester with t-butyloxycarbonyl (Lys,Tyr)80–104. The semisynthetic product was deprotected, purified and combined under anaerobic conditions with a heme peptide, HP 1–65, that was isolated from the products of CNBr cleavage of native cytochrome c. The reconstituted semisynthetic cytochrome c was purified by ion exchange chromatography and was shown to have the same oxygen uptake activity as native cytochrome c when assayed in the succinate oxidase system.