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PubMed1980

Organic acids produced by self-sustaining coacervates in presence of p-nitroaniline and p-phenylene-diamine.

Oleic and malonic acids were found in control samples while p-nitroaniline addition induced production of tricarballylic acid in eight and twelve days exposed samples. Fumaric and citric acids were found in sporadic instances. Addition of p-phenylene diamine to the mixture showed a degeneration process in organic acid production. In some cases production of fumaric acid was positive.

Aniline Compounds↗
PubMed1999

Characterization of a new xylanolytic bacterium, Clostridium xylanovorans sp. nov.

A new xylanolytic bacterium designated strain HESP1T (T = type strain) was isolated from a methanogenic digester. Strain HESP1T was a motile, rod shaped, spore-forming bacterium, which possessed a Gram-positive type cell wall. Glucose, fructose, lactose, trehalose, maltose, raffinose, sucrose, xylan, mannitol, cellobiose, galactose, mannose, melibiose, ribose were fermented to produce, acetate, butyrate, H2, CO2, formate, isobutyrate, and ethanol. Fumarate was fermented to acetate. Glycerol and methanol were also utilized. Sulfate, thiosulfate, nitrate, sulfur and fumarate were not used as electron acceptors. Strain HESP1T had a G + C content of 40 mol% and grew optimally at 37 degrees C and pH 7 on a fructose containing medium. Phylogenetically, strain HESP1T was most related to Clostridium aminovalericum (similarity of 94%) than to C. populeti, C. herbivorans and Eubacterium xylanophilum (average similarity of 92%), all members of subcluster XIVa of the low G + C containing Gram-positive branch. However, strain HESP1T shared little phenotypic and genotypic traits with C. aminovalericum and on the basis of this and phylogenetic evidence, we propose to tentatively designate strain HESP1T as a new species of the genus Clostridium, Clostridium xylanovorans sp. nov. The type strain is HESP1T (= DSM 12503).

Base Sequence↗
PubMed2001

Isolation of mitochondria from Plasmodium falciparum showing dihydroorotate dependent respiration.

Using N2 cavitation, we established a protocol to prepare the active mitochondria from Plasmodium falciparum showing a higher succinate dehydrogenase activity than previously reported and a dihydroorotate-dependent respiration. The fact that fumarate partially inhibited the dihydroorotate dependent respiration suggests that complex II (succinate-ubiquinone reductase/quinol-fumarate reductase) in the erythrocytic stage cells of P. falciparum functions as a quinol-fumarate reductase.

Animals↗
PubMed1978

The metabolism of [14C]bicarbonate by Streptococcus lactis: the synthesis of succinic acid.

Whole cells of Streptococcus lactis C10, when incubated with an energy source, converted fumarate to succinate and malate to lactate. Cell-free extracts of Str. lactis C10 contained fumarate reductase, but no aspartase, adenylosuccinate synthetase and lyase or argininosuccinate synthetase and lyase activity could be detected. Cells grown in the presence of [14C]bicarbonate produced labelled succinate during the synthesis of purine bases. However, the amount of succinate produced by this pathway only accounted for approximately one-sixth of the succinate produced by the cells.

Bicarbonates↗
PubMed1978

Activation of succinate dehydrogenase from adult Fasciola hepatica (Trematoda).

The succinate dehydrogenase of adult Fasciola hepatica was found to exist in active and in active forms. The enzyme was inactivated by 1 micron oxaloacetate and activated by incubation with compounds which bind to the active site (succinate, fumarate, malonate) or by incubation with anions and certain nucleotides. The activation of the enzyme by succinate followed first-order kinetics. The extent of activation of F. hepatica succinate dehydrogenase depended on the nature and concentration of the activator and on the pH. The rate of activation of the enzyme depended on the temperature. In contrast, the fumarate reductase activity of F. hepatica was not activated by incubation with substrate or anions and was not inhibited by oxaloacetate (100 micron). The significance of these results in the regulation of the tricarboxylic acid cycle in parasitic helminths is discussed.

Animals↗
PubMedDate not supplied

Investigations of glutathione conjugation in vitro by 1H NMR spectroscopy. Uncatalyzed and glutathione transferase-catalyzed reactions.

Conjugation reactions of glutathione (GSH) and related thiols with diethyl maleate (DEM) and other alpha, beta-unsaturated carbonyl compounds have been investigated by 1H NMR spectroscopy. The products from the reaction with DEM and diethyl fumarate (DEF) are shown to be the diastereomers of S-(alpha,beta-diethoxycarbonylethyl)glutathione. During the course of the reaction, DEM isomerized to DEF, and the rate of isomerization was dependent upon whether the solvent was 1H2O or 2H2O. The observed rate data exhibit apparent second order kinetic behavior. The reaction of maleate with GSH was considerably slower, and solvent-dependent isomerization was observed, while little reaction of fumarate with GSH was observed at pH 6.5. Reaction of DEM with N-acetyl-L-cysteine followed a similar course to that of GSH, and although L-cysteine reacted rapidly with DEM, it did not promote the isomerization of DEM. Reactions involving penicillamine and N-acetylpenicillamine were considerably slower. Conjugation reactions catalyzed by commercial GSH transferases and selected rat and human purified isoenzymes were also investigated. Of those isoenzymes studied, rat GSH transferase 4-4 was found to exert the greatest degree of stereo control in conjugation reactions with DEF.

Animals↗
PubMed1997

Radiation sterilization of formoterol.

PURPOSE: Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. We have investigated the gamma radiation induced effects on formoterol fumarate by HPLC and ESR spectroscopy. RESULTS AND DISCUSSION: Numerical simulation of the evolution of the ESR signal versus dose was performed using linear regression, quadratic fit and power function. The shape of the dosimetric curve is linear in the range 5-30 kGy. Owing to the weak number of free radicals generated during the irradiation, the accuracy of measurements is low. For a dose of 25 kGy, discriminating irradiated from unirradiated samples is possible if the storage period is less than 250 days. The comparison between chromatographic profiles of irradiated and unirradiated samples showed minor differences. CONCLUSIONS: From our preliminary results, radiosterilization of formoterol fumarate may be technically feasible. Estimation of the irradiation dose by ESR may be possible but, due to the weak number of free radicals generated during the irradiation, the accuracy of measurements appeared low.

Chromatography, High Pressure Liquid↗
PubMed1999

Formoterol and beclomethasone versus higher dose beclomethasone as maintenance therapy in adult asthma.

A total of 132 adult asthmatics who were symptomatic on 500 microg x day(-1) inhaled beclomethasone dipropionate (BDP) were studied in an open-label randomized, parallel group, 12 week, clinical trial. The addition of 12 microg formoterol fumarate solution aerosol (pressurized metered dose inhaler) b.i.d. to BDP at a dose of 500 microg x day(-1) was compared with a higher dose of 1,000 microg x day(-1) BDP. Mean morning premedication peak expiratory flow rate (PEF) during the final week of treatment (primary end-point) increased in both groups compared to baseline. The estimated treatment difference of 20.4 L x min(-1) (95% confidence interval 3.2-37.6) after 12 weeks of treatment was statistically significant (p<0.05) in favour of the formoterol/BDP group. The overall mean morning premedication PEF for the entire treatment period was higher in the formotero/BDP group (p=0.002). The overall number of puffs of rescue medication and asthma symptom scores were less in the formotero/BDP group (p<0.01). Safety and tolerability evaluations were satisfactory in both groups. In conclusion, the results suggest that the addition of formoterol fumarate to the existing dose of an inhaled corticosteroid should be considered as an alternative to increasing the dose of inhaled corticosteroid in the inadequately controlled asthmatic.

Administration, Inhalation↗
PubMed1966

The tricarboxylic acid cycle and glycolysis in relation to ion transport by the ciliary body.

1. The respiration and aerobic glycolysis of pig ciliary processes in oxygenated phosphate and bicarbonate buffers have been investigated. 2. Significant amounts of lactic acid are produced only in the presence of added glucose, but this does not change the endogenous respiration rate. 3. Succinate and citrate increase the oxygen uptake considerably, but pyruvate has almost no effect; oxaloacetate and fumarate stimulate slightly in the presence of glucose. Aspartate and fumarate together stimulate pyruvate utilization and are oxidized as fast as citrate. 4. Ouabain inhibits the oxidation of glucose and other substrates by limiting the ADP supply from the sodium transport system. Cyanide and azide inhibit respiration and stimulate glycolysis. 5. The transport mechanism depends largely on ATP from oxidative phosphorylation and regulates the rate of respiration and glycolysis by controlling ADP production from the Na(+)-K(+)-activated adenosine triphosphatase.

Adenosine Triphosphate↗
PubMed1967

The relationship of 4-hydroxybenzoic acid to lysine and methionine formation in Escherichia coli.

1. A multiple aromatic mutant, Escherichia coli 156:53D2, required 4-hydroxybenzoic acid for rapid aerobic growth on a number of carbon sources. 2. In the absence of 4-hydroxybenzoic acid aerobic growth was stimulated by a mixture of lysine and methionine and by succinate. The influence of the amino acids is attributed to a sparing of succinyl-CoA. 3. Low activities of both alpha-oxoglutarate dehydrogenase and fumarate reductase were found in organisms grown aerobically without 4-hydroxybenzoate and consequently both mechanisms known for the formation of succinate were impaired. 4. The low fumarate-reductase activity in these organisms was due to repression of enzyme synthesis by aeration and not to enzyme inactivation. In contrast lactate dehydrogenase and ethanol dehydrogenase were induced. This is interpreted as the appearance of alternative routes of NADH oxidation when electron transfer to oxygen is impaired. 5. The activities of the other tricarboxylic acid-cycle enzymes tested were little influenced by 4-hydroxybenzoate deficiency, although anaerobiosis resulted in a fall in activity.

Alcohol Oxidoreductases↗
PubMed1968

The effect of adenosine triphosphate on porphyrin excretion and on glycine metabolism in Rhodopseudomonas spheroides.

1. ATP, GTP, CTP and UTP at concentrations of 1mm markedly decrease the amount of coproporphyrin excreted by Rhodopseudomonas spheroides illuminated in a medium containing glycine, succinate and fumarate. 2. The effect of ATP is decreased if ethionine is also added to the medium. 3. Evidence is presented showing that ATP is taken up by the organisms from the medium. 4. ATP is shown to have a marked effect on the utilization of glycine. In the presence of ATP the incorporation of the methylene carbon atom of glycine into the fatty acid moieties of the phospholipids is greatly increased, and more of the carboxyl carbon atom is lost, probably as carbon dioxide. 5. ATP has little effect on the utilization of succinate or fumarate. 6. The possible significance of these results with regard to the control by ATP of porphyrin synthesis and excretion and glycine metabolism is discussed.

Adenosine Triphosphate↗
PubMed1968

The redistribution of carbon label by the reactions involved in glycolysis, gluconeogenesis and the tricarboxylic acid cycle in rat liver.

A scheme is presented that shows how the reactions involved in gluconeogenesis, glycolysis and the tricarboxylic acid cycle are linked in rat liver. Equations are developed that show how label is redistributed in aspartate, glutamate and phosphopyruvate when it is introduced as specifically labelled pyruvate or glucose either at a constant rate (steady-state theory) or at a variable rate (non-steady-state theory). For steady-state theory the fractions of label introduced as specifically labelled pyruvate that are incorporated into glucose and carbon dioxide are also given, and for both theories the specific radioactivities of aspartate and glutamate relative to the specific radioactivity of the substrate. The theories allow for entry of label into the tricarboxylic acid cycle via both oxaloacetate and acetyl-CoA, for (14)CO(2) fixation and for loss of label from the tricarboxylic acid cycle in glutamate, but not for losses in citrate. They also allow for incomplete symmetrization of label in oxaloacetate due to incomplete equilibration with fumarate both in the extramitochondrial part of the cell and in the mitochondrion on entry of oxaloacetate into the tricarboxylic acid cycle. In the latter case failure both of oxaloacetate to equilibrate with malate and of malate to equilibrate with fumarate are considered.

Animals↗
PubMed1970

Anaerobic rat heart. Effects of glucose and tricarboxylic acid-cycle metabolites on metabolism and physiological performance.

1. The ability of tricarboxylic acid-cycle metabolites to influence the physiological performance of the perfused anaerobic rat heart was investigated. Energy expenditure/h [(beats/min)x60xsystolic pressure/g of protein] for various anoxic conditions compared with oxygenated control hearts were: 5mm-glucose, 4.5%; 20mm- or 40mm-glucose, 10%; 20mm-glucose plus fumerate+malate+glutamate, 29%; 20mm-glucose plus oxaloacetate and alpha-oxoglutarate, 31%. 2. The energy expenditure/lactate production ratio was increased by the tricarboxylic acid-cycle metabolites, indicating that alterations in anaerobic physiological performance did not result from changes in glycolysis. 3. Analysis of tissue constituents provided further indication of an enhanced energy status for fumarate+malate+glutamate- and oxaloacetate+alpha-oxoglutarate-perfused hearts; tissue concentrations of both glycogen and ATP were higher than in the 20mm-glucose-perfused groups. 4. A marked increase in the accumulation of succinate in tissues perfused with oxaloacetate+alpha-oxoglutarate or fumarate+malate+glutamate provided further evidence that these metabolites were stimulating mitochondrial energy production under anoxia. 5. These studies indicate that mitochondrial ATP production can be stimulated in an isolated mammalian tissue perfused under anaerobiosis with a resulting enhancement of cell function.

Adenosine Triphosphate↗
PubMed1974

Microbial metabolism of the pyridine ring. Metabolism of 2- and 3-hydroxypyridines by the maleamate pathway in Achromobacter sp.

1. Washed suspensions of two Achromobacter species (G2 and 2L), capable of growth upon 2- and 3-hydroxypyridine respectively as sources of C and N, rapidly oxidized their growth substrate pyridine-2,5-diol (2,5-dihydroxypyridine) and the putative ring-cleavage product maleamate without a lag. Suspensions derived from fumarate plus (NH(4))(2)SO(4) cultures were unable to do so. 2. Extracts of both bacteria oxidized pyridine-2,5-diol with the stoicheiometry of an oxygenase forming 1mol of NH(3)/mol of substrate. 3. Heat-treated extracts, however, formed maleamate and formate with little free NH(3). 4. The conversion of maleamate into maleate plus NH(3) by extracts of strain 2L, fractionated with (NH(4))(2)SO(4), and the metabolism of maleamate and maleate to fumarate by extracts of both strains demonstrated the existence of the enzymes catalysing each reaction of the maleamate pathway in these bacteria. 5. The pyridine-2,5-diol dioxygenase (mol.wt. approx. 340000) in extracts of these Achromobacter species required Fe(2+) (1.7mum) to restore full activity after dialysis or treatment with chelating agents; the enzyme from strain 2L also had a specific requirement for l-cysteine (6.7mm), which could not be replaced by GSH or dithiothreitol. 6. The oxygenase was strongly inhibited in a competitive manner by the isomeric pyridine-2,3- and -3,4-diols.

Alcaligenes↗
PubMed1978

The oxidative activities of membrane vesicles from Bacillus caldolyticus. Energy-dependence of succinate oxidation.

1. The properties of membrane vesicles from the extreme thermophile Bacillus caldolyticus were investigated. 2. Vesicles prepared by exposure of spheroplasts to ultrasound contained cytochromes a, b and c, and at 50 degrees C they rapidly oxidized NADH and ascorbate in the presence of tetramethyl-p-phenylenediamine. Succinate and l-malate were oxidized more slowly, and dl-lactate, l-alanine and glycerol 1-phosphate were not oxidized. 3. In the absence of proton-conducting uncouplers the oxidation of NADH was accompanied by a net translocation of H(+) into the vesicles. Hydrolysis of ATP by a dicyclohexylcarbodi-imide-sensitive adenosine triphosphatase was accompanied by a similarly directed net translocation of H(+). 4. Uncouplers (carbonyl cyanide p-trifluoromethoxyphenylhydrazone or valinomycin plus NH(4) (+)) prevented net H(+) translocation but stimulated ATP hydrolysis, NADH oxidation and ascorbate oxidation. The last result suggested an energy-conserving site in the respiratory chain between cytochrome c and oxygen. 5. Under anaerobic conditions the reduction of cytochrome b by ascorbate (with tetramethyl-p-phenylenediamine) was stimulated by ATP hydrolysis, indicating an energy-conserving site between cytochrome b and cytochrome c. However, no reduction of NAD(+) supported by oxidation of succinate, malate or ascorbate occurred, neither did it with these substrates in the presence of ATP under anaerobic conditions, suggesting that there was no energy-conserving site between NADH and cytochrome b. 6. Succinate oxidation, in contrast with that of NADH and ascorbate, was strongly inhibited by uncouplers and stimulated by ATP hydrolysis. These effects were not observed when phenazine methosulphate, which transfers electrons from succinate dehydrogenase directly to oxygen, was present. It was concluded that in these vesicles the oxidation of succinate was energy-dependent and that the reoxidation of reduced succinate dehydrogenase was dependent on the outward movement of H(+) by the protonmotive force. 7. In support of the foregoing conclusion it was shown that the reduction of fumarate by NADH was an energy-conserving process. 8. If the activities of vesicles accurately represent those of the intact organism it appears that in B. caldolyticus the reduction of fumarate to succinate at the expense of reducing equivalents from NADH is energetically favoured over succinate oxidation even under aerobic conditions. This may be related to the need for an ample supply of succinate for haem synthesis in order to provide cytochromes for the organism.

Adenosine Triphosphate↗
PubMed1980

The role of the membrane-bound hydrogenase in the energy-conserving oxidation of molecular hydrogen by Escherichia coli.

H2-dependent reduction of fumarate and nitrate by spheroplasts from Escherichia coli is coupled to the translocation of protons across the cytoplasmic membrane. The leads to H+/2e- stoicheiometry (g-ions of H+ translocated divided by mol of H2 added) is approx. 2 with fumarate and approx. 4 with nitrate as electron acceptor. This proton translocation is dependent on H2 and a terminal electron acceptor and is not observed in the presence of the protonophore carbonyl cyanide m-chlorophenylhydrazone and the respiratory inhibitor 2-n-heptyl-4-hydroxyquinoline N-oxide. H2-dependent reduction of menadione and ubiquinone-1 is coupled to a protonophore-sensitive, but 2-n-heptyl-4-hydroxy-quinoline N-oxide-insensitive, proton translocation with leads to H+/2e- stoicheiometry of approx. 2. H2-dependent reduction of Benzyl Viologen (BV++) to its radical (BV+) liberates protons at the periplasmic aspect of the cytoplasmic membrane according to the reaction: H2 + 2BV++ leads to 2H+ + 2BV+. It is concluded that the effective proton translocation observed in the H2-oxidizing segment of the anaerobic respiratory chain of Escherichia coli arises as a direct and inevitable consequence of transmembranous electron transfer between protolytic reactions that are spatially separated by a membrane of low proton-permeability.

Escherichia coli↗
PubMed1993

Inactivation of the endogenous argininosuccinate lyase activity of duck delta-crystallin by modification of an essential histidine residue with diethyl pyrocarbonate.

The argininosuccinate lyase activity of duck delta-crystallin was inactivated by diethyl pyrocarbonate at 0 degrees C and pH 7.5. The inactivation followed pseudo-first-order kinetics after appropriate correction for the decomposition of the reagent during the modification period. The plot of the observed pseudo-first-order rate constant versus diethyl pyrocarbonate concentration in the range of 0.17-1.7 mM was linear and went through the origin with a second-order rate constant of 1.45 +/- 0.1 M-1.s-1. The double-logarithmic plot was also linear, with slope of 1.13, which suggested a 1:1 stoichiometry for the reaction between diethyl pyrocarbonate and delta-crystallin. L-Arginine, L-norvaline or L-citrulline protected the argininosuccinate lyase activity of delta-crystallin from diethyl pyrocarbonate inactivation. The dissociation constants for the delta-crystallin-L-arginine and delta-crystallin-L-citrulline binary complexes, determined by the protection experiments, were 4.2 +/- 0.2 and 0.12 +/- 0.04 mM respectively. Fumarate alone had no protective effect. However, fumarate plus L-arginine gave synergistic protection with a ligand binding interacting factor of 0.12 +/- 0.02. The double-protection data conformed to a random Uni Bi kinetic mechanism. Fluorescence-quenching studies indicated that the modified delta-crystallin had minimum, if any, conformational changes as compared with the native delta-crystallin. Inactivation of the enzyme activity was accompanied by an increasing absorbance at 240 nm of the protein. The absorption near 280 nm did not change. Treatment of the modified protein with hydroxylamine regenerated the enzyme activity to the original level. These results strongly indicated the modification of an essential histidine residue. Calculation from the 240 nm absorption changes indicated that only one histidine residue per subunit was modified by the reagent. This super-active histidine residue has a pKa value of approximately 6.8 and acts as a general acid-base catalyst in the enzyme reaction mechanism. Our experimental data are compatible with an E1cB mechanism [Raushel (1984) Arch. Biochem. Biophys. 232, 520-525] for the argininosuccinate lyase with the essential histidine residue close to the arginine-binding domain of delta-crystallin. L-Citrulline, after binding to this domain, might form an extra hydrogen bond with the essential histidine residue.

Animals↗
PubMed1999

Humics as an electron donor for anaerobic respiration.

The possibility that microorganisms might use reduced humic substances (humics) as an electron donor for the reduction of electron acceptors with a more positive redox potential was investigated. All of the Fe(III)- and humics-reducing microorganisms evaluated were capable of oxidizing reduced humics and/or the reduced humics analogue anthrahydroquinone-2,6,-disulphonate (AHODS), with nitrate and/or fumarate as the electron acceptor. These included Geobacter metallireducens, Geobacter sulphurreducens, Geothrix fermentans, Shewanella alga, Wolinella succinogenes and 'S. barnesii'. Several of the humics-oxidizing microorganisms grew in medium with AHQDS as the sole electron donor and fumarate as the electron acceptor. Even though it does not reduce Fe(III) or humics, Paracoccus denitrificans could use AHQDS and reduced humics as electron donors for denitrification. However, another denitrifier, Pseudomonas denitrificans, could not. AHODS could also serve as an electron donor for selenate and arsenate reduction by W. succinogenes. Electron spin resonance studies demonstrated that humics oxidation was associated with the oxidation of hydroquinone moieties in the humics. Studies with G. metallireducens and W. succinogenes demonstrated that the anthraquinone-2,6-disulphonate (AQDS)/AHQDS redox couple mediated an interspecies electron transfer between the two organisms. These results suggest that, as microbially reduced humics enter less reduced zones of soils and sediments, the reduced humics may serve as electron donors for microbial reduction of several environmentally significant electron acceptors.

Aerobiosis↗