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Roles of mucosal bacteria and succinic acid in colitis caused by dextran sulfate sodium in mice.

Intestines of mice with colitis caused by dextran sulfate sodium (DSS) contain more Bacteroidaceae cells than untreated controls. We investigated the roles of intestinal bacteria and succinic acid, a by-product of Bacteroidaceae metabolism, in this model of colitis. CBA/J mice were given 3% DSS in water for 14 days. After mice were anesthetized and killed, concentrations of organic acids in stools from the cecum and colon were measured. The resected rectum and colon were washed with sterile saline; some specimens were incubated with imipenem in saline for 1 h to kill bacteria on the surfaces and others were not. Their homogenates were cultured anaerobically and aerobically. Separately, 1 mL of 20 mM succinic acid was infused into the rectum of mice, whose anal verge was glued. Animals were anesthetized and killed the next day. The rectum and colon were examined histologically. Concentrations of succinate were higher everywhere in the colon of mice with colitis than in controls. Mice with colitis had more Bacteroidaceae cells, especially B. caccae, than controls. Mice given succinate enemas had focal erosions of the mucosa and edema of the submucosa. Succinic acid, produced abundantly by members of the family Bacteroidaceae, especially B. caccae, may be the ulcerogenic agent in DSS colitis.

Acetates↗

Purification of a reconstitutively active iron-sulfur protein (oxidation factor) from succinate . cytochrome c reductase complex of bovine heart mitochondria.

Oxidation factor, a protein required for electron transfer from succinate to cytochrome c in the mitochondrial respiratory chain, has been purified from isolated succinate . cytochrome c reductase complex. Purification of the protein has been followed by a reconstitution assay in which restoration of ubiquinol . cytochrome c reductase activity is proportional to the amount of oxidation factor added back to depleted reductase complex. The purified protein is a homogeneous polypeptide on acrylamide gel electrophoresis in sodium dodecyl sulfate and migrates with an apparent Mr = 24,500. Purified oxidation factor restores succinate . cytochrome c reductase and ubiquinol . cytochrome c reductase activities to depleted reductase complex. It is not required for succinate dehydrogenase nor for succinate . ubiquinone reductase activities of the reconstituted reductase complex. Oxidation factor co-electrophoreses with the iron-sulfur protein polypeptide of ubiquinol . cytochrome c reductase complex. The purified protein contains 56 nmol of nonheme iron and 36 nmol of acid-labile sulfide/mg of protein and possesses an EPR spectrum with the characteristic "g = 1.90" signal identical to that of the iron-sulfur protein of the cytochrome b . c1 complex. In addition, the optimal conditions for extraction of oxidation factor, including reduction with hydrosulfite and treatment of the b . c1 complex with antimycin, are identical to those which facilitate extraction of the iron-sulfur protein from the b . c1 complex. These results indicate that oxidation factor is a reconstitutively active form of the iron-sulfur protein of the cytochrome b . c1 complex first discovered by Rieske and co-workers (Rieske, J.S., Maclennan, D.H., and Coleman, R. (1964) Biochem. Biophys. Res. Commun. 15, 338-344) and thus demonstrate that this iron-sulfur protein is required for electron transfer from ubiquinol to cytochrome c in the mitochondrial respiratory chain.

Animals↗

[Malate oxidation by mitochondrial succinate:ubiquinone-reductase].

Succinate:ubiquinone reductase was shown to catalyze the oxidation of L- and D-stereoisomers of malate by artificial electron acceptors and ubiquinone. The rate of malate oxidation by succinate:ubiquinone reductase is by two orders of magnitude lower than that for the natural substrate--succinate. The values of kinetic constants for the oxidation of D- and L-stereoisomers of malate are equal to: V infinity = 0.1 mumol/min/mg protein, Km = 2 mM and V infinity = 0.05 mumol/min/mg protein, Km = 2 mM, respectively. The malate dehydrogenase activity is fully inhibited by the inhibitors of the dicarboxylate-binding site of the enzyme, i.e., N-ethylmaleimide and malonate and is practically insensitive to carboxin, a specific inhibitor of the ubiquinone-binding center. The enol form of oxaloacetate was shown to be the product of malate oxidation by succinate:ubiquinone reductase. The kinetics of inhibition of the enzyme activity by the ketone and enol forms of oxaloacetate was studied. Both forms of oxaloacetate effectively inhibit the succinate:ubiquinone reductase reaction.

Animals↗

[Succinate-ubiquinone reductase site of the respiratory chain].

Data on succinate-ubiquinone reductase are critically reviewed. The structural and catalytic properties of succinate dehydrogenase and succinate-ubiquinone reductase are compared. The redox components, active centers and proteins involved in the enzyme interaction with ubiquinone are described. Some structural and kinetic features of the succinate-ubiquinone reductase as the respiratory chain component and feasible mechanisms of regulation of the succinate-ubiquinone reductase activity are discussed.

Animals↗

[Effect of benemycin and sodium succinate on metabolism of protons in mitochondria of guinea pig lung and liver tissues].

The data of studies on proton metabolism in mitochondria of the guinea pig lungs and liver with application of benemycin and sodium succinate show that benemycin does not affect the metabolism of protons in the lungs and liver mitochondria. Sodium succinate activates the release of protons from the lungs and liver mitochondria in state 4 according to Chance. When using sodium succinate for reducing the effect of benemycin on theorganism it is found that sodium succinate inhibits the utilization of protons of the lungs and liver mitochondria in state 3 according to Chance and activates this release in state 4, thus favouring an increase in their concentration in the extra-mitochondrial space. Sodium succinate increases survival rate of animals which were administered benemycin to.

Animals↗

[Inhibition of succinate and NADH oxidases of submitochondrial particles by iron chelators and sulfhydryl reagents].

The inhibition of succinate- and NADH-oxidase activities of submitochondrial particles by 4,7-diphenyl-1,10-phenantroline was studied. The inhibition was shown to increase when the particles were pretreated with SH-reagents. The treatment of submitochondrial particles with ethanol in the presence of 1,10-phenantroline resulted in a complete inactivation of succinate oxidase and succinate: tetramethyl-n-phenyldiamine reductase; the succinate PMS reductase activity was only partially inhibited after such treatment. It is concluded that tetramethyl-n-phenyldiamine and phenazine metasulfate react with different sites of the succinate dehydrogenase complex. The changes in the properties of submitochondrial particles after ethanol--phenantroline treatment are apparently due to the effect of non-polar solvent rather than to the extraction of non-haem iron.

Animals↗

Interactions between 4-aminobutyrate aminotransferase and succinic semialdehyde dehydrogenase, two mitochondrial enzymes.

Physical interactions between the enzymes involved in the catabolism of the neurotransmitter 4-aminobutyrate were detected by means of affinity chromatography and fluorescence techniques. By immobilizing one enzyme (4-aminobutyrate aminotransferase) indirectly through antibodies bound to protein A-Sepharose, it was possible to demonstrate that succinic semialdehyde dehydrogenase interacts with the aminotransferase at neutral pH and ionic strength values higher than 0.2. Increasing the ionic strength of the medium results in dissociation of the "enzyme cluster." Binding of succinic semialdehyde dehydrogenase to the aminotransferase tagged with a fluorescent probe was detected by polarization of fluorescence measurements at neutral pH. Upon saturation of the aminotransferase with succinic semialdehyde dehydrogenase, the polarization of fluorescence increases from 0.13 to 0.21. The results are consistent with a model in which one molecule of succinic semialdehyde dehydrogenase is bound to one molecule of 4-aminobutyrate aminotransferase with an equilibrium dissociation constant of 0.1 microM. Since the concentrations of both enzymes in the mitochondrial matrix have been estimated to be around 2 microM, the results obtained with the purified mitochondrial enzymes strongly suggest that the aminotransferase is saturated with succinic semialdehyde dehydrogenase to form a stable enzymatic complex under in vivo conditions.

4-Aminobutyrate Transaminase↗

[Reconstitution of succinate-ubiquinone reductase of the respiratory chain of mitochondria].

A soluble protein fraction, which confers the reactivity of soluble succinate dehydrogenase towards ubiquinone, was isolated from beef heart mitochondria. This fraction contains three polypeptides as revealed by SDS-electrophoresis; the major peptide (about 80% of protein) has a molecular weight less than 13 000. Several properties of the reconstituted succinate-ubiquinone reductase, i. e. the turnover number of succinate dehydrogenase inhibitor sensitivity, stability and reactivity towards artificial electron acceptors were found to be identical to those of the native succinate-ubiquinone region of the respiratory chain. A model of the minimal functionally active structure capable of reduction of ubiquinone by succinate is proposed.

Animals↗

Guanidino succinic acid is not the endogenous source of endothelium-derived relaxing factor in the porcine isolated splenic artery.

The possibility that guanidino succinic acid is the major endogenous source of endothelium-derived relaxing factor has been examined using the porcine isolated splenic artery. Administration of 100 microM NG-nitro-L-arginine methyl ester (L-NAME) caused a substantial, endothelium-dependent contraction of the splenic artery that was inhibited by L-arginine (1 mM) but was unaffected by D-arginine (1 mM). L-NAME enhanced the responsiveness of the splenic artery to 5-hydroxytryptamine in endothelium-intact segments only, and the potentiating action of L-NAME was inhibited by L-arginine but not by D-arginine. Administration of 100 microM guanidino succinic acid did not relax the splenic artery and it did not inhibit or reverse contractions of the splenic artery induced by L-NAME. Administration of guanidino succinic acid, either before or after L-NAME, did not affect the potentiating action of L-NAME on the 5-hydroxytryptamine-induced contraction of the splenic artery in endothelium-intact segments. Although substance P caused an endothelium-dependent relaxation of preconstricted segments of the splenic artery, guanidino succinic acid did not relax preconstricted, endothelium-intact or endothelium-denuded segments of the artery. L-NAME inhibited the relaxation induced by substance P in endothelium-intact preparations. The findings for the effects of arginine are consistent with L-arginine being a source of endothelium-derived relaxing factor in the porcine splenic artery, while observations with guanidino succinic acid indicate that it is not a substrate for the synthesis of endothelium-derived relaxing factor in this blood vessel.

Animals↗

Subunit 8 of the Saccharomyces cerevisiae cytochrome bc1 complex interacts with succinate-ubiquinone reductase complex.

We have investigated the function of subunit 8 of the cytochrome bc1 complex by generating six site-directed mutants, F46C, R51S, P62V, G64A, R91N, and W69-stop, in the cloned QCR8 gene and expressing the mutated genes in a Saccharomyces cerevisiae strain in which the chromosomal copy of QCR8 is deleted. The W69-stop mutation impairs assembly of the bc1 complex and growth of yeast on nonfermentable carbon sources as does deletion of QCR8 [Maarse, A. C., De Haan, M., Schoppink, P. J., Berden J. A., and Grivell, L. A. (1988) Eur. J. Biochem. 172, 179-184], implying that the C-terminus of subunit 8 is important for assembly and/or the stability of the bc1 complex. The F46C, R51S, P62V, G64A, and R91N mutations do not affect the growth of yeast on nonfermentable carbon sources, not do they lower the activity or alter the inhibitor sensitivity of the bc1 complex. Rather, some of the mutations increase the cytochrome C reductase activity of the bc1 complex by as much as 40%. However, succinate-ubiquinone reductase activity was consistently reduced 40-60% in mitochondrial membranes from these mutants, while NADH-ubiquinone reductase activity was not affected. In addition, the activation of succinate-ubiquinone reductase activity by succinate was diminished by the F46C, R51S, P62V, and G64A mutations. These results indicate that the cytochrome bc1 complex participates in electron transfer from succinate to ubiquinone in situ and also suggest an interaction between succinate-ubiquinone reductase and cytochrome bc1 complex which involves subunit 8 of the bc1 complex.

Amino Acid Sequence↗

Protection by GABA and succinic semialdehyde of seed germination and some enzymatic activities against high concentration of hydroxylamine.

Hydroxylamine was found to stimulate germination of Lupinus albus at concentrations inferior to 10 mM and to inhibit it greatly at 20 mM concentration. This inhibition was partially restored by GABA or succinic semialdehyde. Hydroxylamine, at high concentrations, behaved as inhibitor in vivo on GABA 2-oxyglutarate amino-transferase and succinic semialdehyde dehydrogenase NAD-dependent, whereas it behaved as activator on succinic semialdehyde dehydrogenase NADP-dependent. No effects were observed on the enzymatic activities and the inhibited germination was partially restored, after GABA and succinic semialdehyde had been added to a growth medium with a 20 mM hydroxylamine concentration. A possible protection mechanism of GABA and succinic semialdehyde against hydroxylamine action is discussed.

Aminobutyrates↗

Postischemic administration of succinate reverses the impairment of oxidative phosphorylation after cardiac ischemia and reperfusion injury.

BACKGROUND: Ischemia and reperfusion (IR) can lead to impaired myocardial mechanical function and inhibition of key metabolic enzyme systems after IR. In this study, we sought to identify the postischemic lesion in oxidative phosphorylation and hypothesized that selective substrate repletion would restore mitochondrial metabolic function during reperfusion. METHODS AND RESULTS: Isolated rat hearts were subjected to global ischemia (25 minutes; 37 degrees C) and reperfusion (40 minutes). Left ventricular developed pressure (LVDP) and the cytochrome a,a3 redox state (near infrared spectroscopy) were continuously monitored. Oxygen consumption was measured for the NADH (mitochondrial complex I) and FADH2 (complex II) pathways in both the resting and maximal ADP-stimulated states. Myocellular oxidative phosphorylation capacity was measured using an NADPH-linked assay specific for mitochondrial ATPase. The hearts were randomized to either succinate (200 micromol/L) or control for the first 5 minutes of reperfusion after ischemia. IR in the control group resulted in an impairment of NADH (complex I) oxidative phosphorylation capacity (1.4+/-0.4 versus control 3.9+/-0.6 nmol ATP/min/mg) and depressed LVDP (49+/-3% of baseline; P<.05). The oxidative phosphorylation capacity for the succinate-using FADH2 pathway remained intact (2.6+/-0.3 versus 2.4+/-0.4). Postischemic succinate administration enhanced LVDP recovery after IR (89+/-8% of baseline; P<.05). Diminished electron transport resulted in depletion of electrons from cytochrome a,a3 during ischemia and early reperfusion, which was reversed by providing succinate as substrate. CONCLUSIONS: Cardiac ischemia and reperfusion results in a defect at mitochondrial complex I but not complex II. Cytochrome a,a3 undergoes anomalous oxidation during ischemia. Postischemic administration of succinate infusion restores the cytochrome a,a3 redox state balance and myocardial function after IR.

Adenosine Triphosphate↗

Effect of the nonionic detergent Triton X-100 on mitochondrial succinate-oxidizing enzymes.

Specific activities of succinate:coenzyme Q reductase, ubiquinone:cytochrome c reductase, cytochrome oxidase, succinate:cytochrome c reductase, succinate oxidase, and ubiquinol oxidase have been measured in rat liver mitochondria in the presence of Triton X-100. The last three activities are much more sensitive to Triton X-100 than the first ones; the data suggest that the electron transport chain components cannot react with each other in the presence of the detergent. At least in the case of succinate:cytochrome c reductase, reconstitution of the detergent-treated membranes with externally added phospholipids reverses the inhibition produced by Triton X-100. These results support the idea that the respiratory chain components diffuse at random in the plane of the inner mitochondrial membrane; the main effect of the detergent would be to impair lateral diffusion by decreasing the area of lipid bilayer. When detergent-treated mitochondrial suspensions are centrifuged in order to separate the solubilized from the particulate material, only the first three enzyme activities mentioned above are found in the supernatants. After centrifugation, a latent ubiquinol:cytochrome c oxidase activity becomes apparent, whereas the same centrifugation process produces inhibition of cytochrome c oxidase in the presence of certain Triton X-100 concentrations. These effects could be due either to a selective solubilization of regulatory or catalytic subunits or to a conformational change of the enzyme-detergent complex.

Animals↗

Separation and characterization of NAD- and NADP-specific succinate-semialdehyde dehydrogenase from Escherichia coli K-12 3300.

Two distinct proteins endowed with succinate-semialdehyde dehydrogenase (succinate-semialdehyde:NAD(P)+oxidoreductase, EC 1.2.1.16) activity were separated and partially purified by ammonium sulphate fractionation or Sephadex G-200 gel-filtration or both. They differ by coenzyme specificity (NAD or NADP), molecular weight, temperature and pH resistance, pH-activity curves, beta-mercaptoethanol activation. Moreover, the NADP-specific enzyme catalyzes only the oxidation of succinate-semialdehyde among a number of aldehydes tested, whereas the NAD-specific form is active also towards n-butyraldehyde. The Km for the substrate is also appreciably different according to the coenzyme specificity, while the Km values for NAD and NADP are quite similar. Finally, the growth of the cells on gamma-aminobutyrate as the sole source of nitrogen resulted in enhanced level of the NAD-dependent succinate-semialdehyde dehydrogenase, with concurrent decrease of the alternate enzyme activity. On the basis of the above results, distinct metabolic roles are suggested for the two enzymes forms.

Aldehyde Oxidoreductases↗

Air saturation of the medium reduces the rate of phosphorylating oxidation of succinate in isolated mitochondria.

Rat brain mitochondria were isolated and their respiration was polarographically measured without contact with air oxygen. Gas-saturated experimental mixtures close to the in vivo partial oxygen pressure (normoxic) were compared with the air-saturated, i.e. hyperoxic, mixtures. The rate of phosphorylating oxidation of added succinate under normoxic conditions was found to be 70-100% higher compared with hyperoxic ones. The addition of succinate dehydrogenase activators results in a more than two-fold stronger stimulation of succinate oxidation under normoxia than under hyperoxia. Thiol group donors are shown to stimulate respiration under hyperoxia and not under normoxia. Hyperoxic conditions prevented oxidation of the low succinate concentrations corresponding to the physiological ones.

Air↗

Classification of fumarate reductases and succinate dehydrogenases based upon their contrasting behaviour in the reduced benzylviologen/fumarate assay.

Reduction of fumarate by soluble beef heart succinate dehydrogenase has been shown previously by voltammetry to become increasingly retarded as the potential is lowered below a threshold potential of -80 mV at pH 7.5. The behaviour resembles that of a tunnel diode, an electronic device exhibiting the property of negative resistance. The enzyme thus acts to oppose fumarate reduction under conditions of high thermodynamic driving force. We now provide independent evidence for this phenomenon from spectrophotometric kinetic assays. With reduced benzylviologen as electron donor, we have studied the reduction of fumarate catalysed by various enzymes classified either as succinate dehydrogenases or fumarate reductases. For succinate dehydrogenases, the rate increases as the concentration of reduced dye (driving force) decreases during the reaction. In contrast, authentic fumarate reductases of anaerobic cells (and 'succinate dehydrogenase' from Bacillus subtilis) neither exhibit the electrochemical effect nor deviate from simple kinetic behaviour in the cuvette assay. The 'tunnel-diode' effect may thus represent an evolutionary adaptation to aerobic metabolism.

Animals↗

Purification and characterization of a coenzyme-A-dependent succinate-semialdehyde dehydrogenase from Clostridium kluyveri.

Cell extracts of Clostridium kluyveri, grown on ethanol plus succinate contained a succinyl-CoA:CoA transferase (0.28 U/mg), a coenzyme-A-dependent succinate-semialdehyde dehydrogenase (0.73 U/mg) and a NAD(+)-dependent 4-hydroxybutyrate dehydrogenase (0.25 U/mg). The semialdehyde dehydrogenase, which catalyzed the NADPH-dependent reduction of succinyl-CoA to succinate semialdehyde, was purified 59-fold to homogeneity. A molecular mass of 115000 Da was determined for the native enzyme; SDS/PAGE revealed one protein band at 55,000, indicating that the active form is a dimer. The enzyme was highly specific for succinyl-CoA and succinate semialdehyde. The pH optimum was 7.0 for the reduction of succinyl-CoA, and 8.5 for the reverse reaction. Km values were determined for both the forward and reverse directions. The kinetic data suggest a ping-pong mechanism.

Acyl Coenzyme A↗

CORRELATION OF SUCCINATE METABOLISM AND VIRULENCE IN SALMONELLA TYPHIMURIUM.

Herzberg, Mendel (University of Florida, Gainesville), and Mudhaffer J. Jawad, and Darrell Pratt. Succinate metabolism and virulence in Salmonella typhimurium. J. Bacteriol. 89:185-192. 1965.-A virulent, smooth strain of Salmonella typhimurium (Wild-7) grew slowly with succinate as sole carbon source (Suc-L). Old stock cultures yielded a smooth variant which grew rapidly (Suc-E). Visible colonies of Suc-E appeared in 24 hr, whereas Suc-L required 48 hr. Differences other than the response to succinate were not demonstrable between the two strains; ld(50) values of both strains were similar, but equivalent numbers of Suc-E required longer periods of time to kill mice. Recovery of bacteria from liver and spleen homogenates revealed that Suc-L remains as such in vivo, but Suc-E populations change to Suc-L. By the eighth day of infection, the organisms were 93 to 100% Suc-L; thus, mortality was due to the Suc-L population developed in vivo and not the Suc-E of the original inoculum. Animal passage of a number of stock cultures of S. typhimurium of diverse origin, all Suc-E type, invariably yielded Suc-L. Slow utilization of succinate appears to be correlated with virulence.

Animals↗