Succinoxidase System Research Articles

THE OXIDATION OF SUCCINATE IN EXTRACTS OF XANTHOMONAS PHASEOLI

Succinoxidase and succinic dehydrogenase were found in cell-free extracts of Xanthomonas phaseoli, obtained by sonic oscillation, and remained largely in the supernatant solution after ultracentrifugation. The effect of time of exposure of the cells to sonic oscillation on cell breakage was found to follow first order reaction kinetics, as was the "solubilization" of succinic dehydrogenase and succinoxidase. It appears that the two enzymatic activities are released from the cell in a particulate form which is further fragmented on continued treatment in the sonic oscillator.The clear supernatant solution obtained after ultracentrifugation of the cell-free extract was found to contain those members of the electron transport chain which had previously been found in the intact cell, namely, flavoprotein and cytochromes b1, a1, and a2. These substances could be reduced by the addition of succinate. Malonate prevented this reduction. The effects of various inhibitors on the succinoxidase system and on succinic dehydrogenase are presented and discussed in relation to the operation of the electron transport chain in the oxidation of succinate by this organism.

The reversible inhibition of succinoxidase by naphthoquinones

Ball, Anfinsen, and Cooper (1947) demonstrated that 2-hydroxy-3-alkylnaphthoquinones, which possess antimalarial activity, exert their inhibitory effect on respiration by inhibiting succinoxidase. They pinpointed the locus of action of these compounds to a site between cytochromes b and c in the electron transport system. The recent discovery of a benzoquinone, coenzyme Q 10 (CoQ 10), as a cofactor essential for electron transport ( Crane, Hatefi, Lester, and Widmer, 1957) prompted us to investigate the possibility that the naphthoquinones were inhibiting at the CoQ 10 site. The present communication describes studies which demonstrate that the inhibitory effect of the antimalarial naphthoquinones on the succinoxidase system of beef heart electron transport particles (ETP) can be reversed by CoQ 10 and related compounds. Antimycin A, also known to inhibit between cytochromes b and c in the electron transport chain ( Potter and Reif, 1952), is not so antagonized.

Biochemical Effects of Gamma Irradiation on the Succinoxidase System, in vitro

The succinoxidase system and each constituent enzyme, (succinic dehydrogenase and cytochrome oxidase), which are obtained from liver of mice and rats and from the heart of the cow, were irradiated in vitro with Co/sup 60/ gamma rays. Inactivation of the enzyme systems was observed to occur with relatively large doses of gamma radiation. Succinic dehydrogenase was found to be more radiosensitive than cytochrome oxidase in all preparations. Effect of gamma irradintion on the enzyme systems localized in mitochondria and on the nuclei of rat liver was compared. The enzyme systems in the nuclear fraction were relatively more radiosensitive to gamma inactivation than those in the mitochondriai fraction. (Abstr. Japan Med., 2: No. 11, Nov. 1962)

Studies on the electron transport system XXVI. Specificity of coenzyme Q and coenzyme Q derivatives

In succinic dehydrogenase complex there are three alternative pathways by which quinones mediate the oxidation of succinate by cytochrome c or oxygen. The first, mediated by menadione, 2,3-dimethoxy, 5-methyl benzoquinone and the short chain coenzyme Q analogues terminates at external cytochrome c and is antimycin insensitive. The second, mediated only by lipophilic homologues of coenzyme Q (Q 2, Q 3, Q 6, Q 10) terminates at external cytochrome c and is antimycin sensitive. The third, mediated by coenzymes Q 2, Q 3, Q 6, Q 10 and in part by Q 0, Q 1, plastoquinone and heptyl and heptadecyl coenzyme Q terminates at molecular oxygen, involves bound cytochrome c and is antimycin sensitive. There is a close correlation between the effects of Q analogues on the succinoxidase activity of acetone extracted SDC and the effects on the succinoxidase activity of acetone extracted electron transport particle ETP. This suggests that the reconstituted succinoxidase system of succinic dehydrogenase complex closely resembles that of electron transport particle from which it was derived. Succinic cytochrome c reductase activity of succinic dehydrogenase complex, in principle, is a measure of the segment of the electron transfer chain which has been detached from the cytochrome a terminus of the chain. This segment by virtue of changes induced by the cleavage process shows a new pattern of quinone specificity. Only derivatives of 2,3-dimethoxy, 5-methyl benzoquinone with two or more isoprenoid units in the side chain at carbon 6 are able to serve as mediators in the antimycin sensitive oxidation of succinate by cytochrome c. The antimycin insensitive pathway involving cytochrome c via other quinones involves transfer of electrons from a site in the electron transfer chain prior to the locus for antimycin action.

On the nature of the block in the succinic oxidase system of anaerobically grown yeast

1. 1. The apparent absence of succinic dehydrogenase activity in anaerobically grown yeast, reported in the literature, was due to the employment of assay methods unsuitable for the measurement of the activity of this enzyme. With the aid of phenazine methosulfate, a reagent capable of reacting directly with the primary dehydrogenase, it has been shown that anaerobic yeast contains a high level of succinic dehydrogenase. 2. 2. Slonimski's observation of the virtual absence of succinic-cytochrome c reductase in anaerobically grown cells has been confirmed. 3. 3. During oxygenation of anaerobically grown cells a rapid, induced synthesis of the succinic-cytochrome activity occurs, which may be accompanied by a moderate increase in dehydrogenase activity. At the end of O 2 adaptation the ratio of succinic dehydrogenase to succinic-cytochrome c reductase activities is the same as in aerobically grown cells. 4. 4. The virtual absence of succinic oxidase in anaerobically grown cells is thus entirely due to the absence of the electron-transport system and not that of the dehydrogenase. O 2 adaptation thus entails synthesis of the hemoproteins and the incorporation of succinic dehydrogenase in the respiratory chain. 5. 5. The possible relevance of these observations to the apparent absence of other cytochrome-reducing dehydrogenases in anaerobic yeast has been pointed out.

Oxidative processes in hypervitaminosis A in albino rats.

Albino rats were made hypervitaminotic A by feeding 30,000 iu of vitamin A daily by mouth; the effect of this hypervitaminosis was compared with a similar pair-fed group. Food consumption and body weight gain were reduced. Study of liver and kidney slices shows that the latter manifest no significant increase in oxygen consumption in presence of succinate or acetate. There is slight increase in O2 consumption in brain homogenates. Liver homogenate shows 15.2% inhibition with succinate and 5.6% with ascorbate oxidation. Liver homogenate shows 19.3% inhibition of succinate dehydrogenase activity by Thunberg technique with methylene blue indicator. It is concluded that hypervitaminosis A inhibits liver respiration by affecting the dehydrogenase, or any immediate step following it, and the cytochrome c-cytochrome oxidase end of the succinoxidase system is little affected.

Coenzyme Q. IV. Coenzyme activity of 6-isoprenoid and other derivatives of 2, 3-dimethoxy-5-methylbenzoquinone.

2,3 - Dimethoxybenzoquinone and 2,3 - dimethoxy - 5-methylbenzoquinone showed no coenzymatic activity in a succin-oxidase system. 2,3-Dimethoxy-5,6-dimethyl-benzoquinone and coenzyme Q1 showed low activity. Coenzyme Q2, Q3 and hexahydro-coenzyme Q4 showed activity comparable to that of coenzyme Q10.

The inhibitory effect of Antipiriculin-A and some fungicidal chemicals on the organic acid and energy metabolism of Piricularia oryzae

In the present paper, the inhibitory effects of Antimycin-A (Antipiriculin, AP), Blastmycin (BM), and Phenyl mercuric acetate (PMA) on the fundamental metabolic systems of P. oryzae are reported. The enzyme solution of P. oryzae was able to oxidize some organic acids found in TCA cycle, and this oxidation, especially that of succinate or lactate, was remarkably inhibited by AP, BM, and PMA. The endogenous respiration of the enzyme solution, however, was not inhibited by these inhibitors, but was inhibited by a high concentration of PMA. As to the terminal respiratory systems in P. oryzae, the following series of hydrogen doner and acceptor systems were presented, that is, succinic dehydrogenase, succinoxidase system, and cytochrome oxidase system. Both AP and BM showed definitely a specific inhibition to the succinoxidase system, whereas PMA inhibited all these systems. The oxidative phosphorylation and glycolysis in P. oryzae were also found not to be affected by AP and BM, although PMA seemed to inhibit the glycolysis slightly.

Interaction of non-specific reducing and oxidizing agents with the cytochrome system in heart-muscle preparations

1. 1. Under anaerobic conditions, 2:3-dimercaptopropanol (BAL), ascorbate and a number of monothiols brought about the reduction of cytochromes b, c and a in Keilin and Hartree heart-muscle preparations. The reduction of cytochrome b under these conditions was relatively slow and incomplete, but was made still slower by the addition of antimycin. 2. 2. Under anaerobic conditions, oxidation of reduced cytochromes b, c and a was brought about by hydrogen peroxide in the presence of cyanide, by o-iodosobenzoate and the disulphide cystamine. The oxidation of cytochrome b under these conditions was relatively fast, but was inhibited by the addition of antimycin. 3. 3. From these experiments it was concluded that antimycin inhibits the respiratory chain between cytochrome b and the point of interaction of these reducing and oxidizing agents, tentatively identified as the BAL-sensitive factor. 4. 4. Succinate, but not malonate, protected the succinic oxidase system from inhibition by BAL in the presence of air. Antimycin, but not cyanide, prevented succinate from protecting the BAL-sensitive factor. 5. 5. From these protection experiments it was concluded that the antimycin-sensitive factor lies between succinic dehydrogenase and the BAL-sensitive factor. 6. 6. Under the conditions of the BAL-air inhibition process, the protective effect of succinate was probably to prevent the oxidation of BAL by making the reaction medium essentially anaerobic. When, however, the oxidation of succinate was limited by addition of cyanide, under these conditions, it was found that oxidation of BAL took place to the extent of about one third of that in the presence of cyanide alone. This amount of oxidation of BAL would be expected to lead to substantial inhibition of succinic oxidase activity, but in fact no inhibition was observed.

節遮断薬とコハク酸酸化酵素系

節遮断薬とコハク酸酸化酵素系

Oxidation of Krebs Cycle Acids by Tissue Slices and Cytoplasmic Particles from Apple Fruit

It has previously proved difficult to demonstrate the Krebs cycle in either cytoplasmic particles or tissue slices obtained from apple fruit. In the present investigation, evidence was obtained for the operation of the classical Krebs cycle-cytochrome oxidase respiratory system in cut tissue and mitochondria from Granny Smith apples. The respiration of cut tissue increased when either citrate, a-ketoglutarate, succinate, malate, fumarate, or pyruvate were added. Both the endogenous and acid-stimulated respiration were inhibited by malonate, cyanide, and azide. The rapid oxidation of Krebs cycle acids by cytoplasmic particles from apple flesh was also demonstrated. These particles showed cytochrome oxidase act.ivity and contained a cytochrome c-dependent succinoxidase system.

Effect of peroxidase on the reconstructed succinoxidase system

Effect of peroxidase on the reconstructed succinoxidase system

The Kinetics and Inhibition of Cytochrome Components of the Succinic Oxidase System: III. CYTOCHROME b

The Kinetics and Inhibition of Cytochrome Components of the Succinic Oxidase System: III. CYTOCHROME b

The effect of tranquilizing agents and related compounds on the succinoxidase system

The effect of 13 tranquilizing agents or their pharmacologically inactive analogs on the succinoxidase system was determined. The phenothiazine group of drugs inhibited the succinoxidase system most strongly and was followed closely in this property by reserpine, the derivatives of phenyl carbinol being the least active. Quiactin was relatively inactive. In all cases, cytochrome oxidase was more sensitive and succinic dehydrogenase less sensitive to inhibition than the complete succinoxidase system. Brain succinoxidase was less sensitive to inhibition than liver succinoxidase. It is concluded that inhibition of succinoxidase is not related to the mechanism of action of the tranquilizers.

The effect of 2,3-dimercartopropanol on the unsaturated fatty acids of heart-muscle preparation

1. 1. The oxidation of 2,3-dimercaptopropanol (BAL) by oxygen in the presence of the Keilin and Hartree heart-muscle preparation is coupled with the peroxidation of unsaturated fatty acids. This process is probably catalysed by traces of Fe 2+ present in the preparation. 2. 2. A number of substances, particularly Fe 2+, haemoglobin and cytochrome c, increased the peroxidation when added together with BAL but protected the succinic oxidase system against BAL. 3. 3. On the other hand, treatment of the heart-muscle preparation with an ion-exchange resin decreased the peroxidation but made the succinic oxidase more sensitive to BAL. 4. 4. Serotonin almost completely inhibited peroxidation in the presence of BAL but did not protect the succinic oxidase system. 5. 5. It is concluded that peroxidation of lipid in the presence of BAL is not an important cause of the inactivation of the respiratory chain by BAL. 6. 6. On the other hand, lipid peroxidation probably makes a major contribution to the “excess oxygen uptake” (oxygen in excess of that required to oxidize BAL to the disulphide). 7. 7. A part of the BAL is oxidized through the cytochrome c-cytochrome c oxidase system. This does not lead to excess oxygen uptake, lipid peroxidation, or inactivation of the respiratory chain. 8. 8. It is concluded that a third pathway for the oxidation of BAL leads to the inactivation of the succinic oxidase, probably by causing the oxidation of an unidentified component of the preparation. The inactivation is inhibited by cyanide and ethylenediaminetetraacetate.

Reconstitution of the succinic oxidase system from soluble succinic dehydrogenase and a particulate cytochrome system preparation.

Reconstitution of the Succinic Oxidase System from Soluble Succinic Dehydrogenase and a Particulate Cytochrome System Preparation

The site of electron transfer to various acceptors in sucinoxidase system, with special reference to that of ethylurethane.

A study of succinoxidase system in rat liver mitochondria has been made, with special reference to the site of action of ethylurethane, and the site of electron transfer to several electron acceptors in this system.1. The inhibitory action of ethylurethane on succinoxidase system varied with the variety of acceptors used and it was not observed when brilliant cresyl blue was the acceptor. The inhibition was completely reversible up to the concentration of 0.5 M.2. The existence of two pathways: an “antimycin A-sensitive” and an “antimycin A-resistant, ” was indicated to link ferricyanide, 2, 6-dichlorophenolindophenol, and methylene blue with the succinoxidase system. One of the factors involved in the antimycin A-sensitive pathway is cytochrome c.3. The sensitivity of succinoxidase toward ethylurethane was exaggerated by the treatment with antimycin A and BAL and by the addition of cytochrome c. On the other hand, simultaneous addition of ethylurethane failed to protect the inhibition by BAL. Antimycin A titer of succinoxidase was decreased slightly by the presence of ethylurethane.4. From these results, the mechanism of action of ethylurethane was discussed together with that of antimycin A and BAL, and it was concluded that the site of action of ethylurethane lies at the portion of cytochrome b and Slater factor.

癌細胞のコハク酸酸化酵素系

With a view to ascertain the common specific characteristics of the respiratory enzyme system of cancer cells and changes in the enzyme activities in consonant with their origin and grade of differentiation the authors carried out a series of histochemical and biochemical investigations by studying the succinoxidase system, cytochrome oxidase system, DPNH-dehydrogenase system, and endogenous dehydrogenase system in various tumorous tissues, homologous non-tumorous tissues, and precancerous tissues, all from human or animals, by using cell suspensions, tissue slices, tissue homogenates, and mitochondria fractions with tetrazolium salts (NT, Nitro-NT, and Nitro-BT); and arrived at the following conclusions:1. As for the activity of the succinoxidase system in normal glandular epithelial cells it is stronger in those matured and differentiated cells possessing vigorous metabolic function than in immature cells. However, in the cancer tissues, such as hepatoma and adenocarcinoma, the activity is generally lower than in the homologous normal tissues. In the cancer tissue the more highly differentiated cancer cells show stronger activity; and it is lowest in undifferentiated cancer cells.2. Normal squamous epithelial cells show generally a lower activity, and of them young basal cells present a higher activity. However, in the case of squamous cell cancer the activity is still stronger, and in contrast it is higher in poorly differentiated cancer cells.3. In normal non-epithelial cells, with a few exceptions (e. g. muscle cells), the activity of young cells is rather stronger than that of mature cells, and in the case of sarcomas (including leukemic cells) their activity is stronger than that of homologous tissue cells.4. The endogenous dehydrogenase system activity of both cancer cells and sarcoma cells (including leukemic cells) is stronger than that of homologous non-tumorous cells.5. The succinoxidase system activity of the rat liver tissue is elevated gradually at the precancerous stage by the DAB administration, and the activity is markedly diminished when the tissue became cancerous. On the other hand, the endogenous dehydrogenase system activity, rising gradually from the precancerous stage, does not fall even when cancerized.6. In cancer cells the shape and structures of the mitochondria and their respiratory enzyme activities are on the whole irregular.7. Cancer cells are apt to be easily destroyed in the course of the enzyme reaction, and moreover, it is liable to bring about the demolition and the decreased respiratory enzyme activity of mitochondria due to the destructive procedures as homogenization and or other treatments.

The mechanism of interaction between two electron acceptors (relay effect) in succinoxidase system.

The mechanism of interaction between two electron acceptors (relay effect) in succinoxidase system.

Some Effects of Carbon Dioxide-Bicarbonate Mixtures on the Oxidation and Reduction of Cytochrome c by Ricinus Mitochondria

THE observation that the succinic oxidase system of Ricinus mitochondria is inhibited by concentrations of carbon dioxide above about 20 per cent1 has led us to investigate the effects of carbon dioxide on components of the respiratory chain.