Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fumarates”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,495 records · Page 83Linked to original sources
PubMed1978

Effect of medium composition on the growth and asparaginase production of Vibrio succinogenes.

Asparaginase synthesis by Vibrio succinogenes is induced by ammonium ions. Synthesis occurs throughout exponential phase, and in early stationary phase asparaginase accounts for about 5% of the total soluble protein. The organism grows best when fumarate is provided as the terminal electron acceptor of the formate-oxidizing cytochrome system. Yeast extract or enzyme-hydrolyzed proteins are effective nutrient sources. In an ammonium formate-sodium fumarate medium, where maximum growth and asparaginase synthesis occurs, the total enzyme yield (international units per liter of culture) is about one-tenth that obtainable with a good asparaginase-producing strain of Escherichia coli. The energetic inefficiency of V. succinogenes appears to cause a low yield of cells and therefore low total enzyme yield. However, the levels of asparaginase accumulated within cells raise questions about the organism's protein synthesizing system.

Asparaginase↗
PubMed1979

L-Glutamine formation by Flavobacterium rigense.

A penicillin-resistant mutant of Flavobacterium rigense designated as strain 703, FERM-P no. 3628, was obtained after ultraviolet treatment of F. rigense FERM-P no. 3556. The parent strain produces 0-2-hydroxypropylhomoserine from 1,2-propanediol. The mutant was found to be a good producer of L-glutamine. The physiological characteristics of strain 703 were different from the general group of L-glutamic acid-producing bacteria. Strain 703 required L-tryptophan and thiamine but not biotin for its growth. L-Glutamine formation on a specific basis, however, was independent of L-tryptophan and thiamine. Biotin and penicillin were also not effective. Only ammonium fumarate acted as an effective factor on L-glutamine formation. Accumulation of L-glutamine by strain 703 was 10 mg/ml at 30 degrees C for 48 h in a chemically defined medium containing 3% diammonium fumarate.

Flavobacterium↗
PubMed1990

Reductive dehalogenation of carbon tetrachloride by Escherichia coli K-12.

The formation of radicals from carbon tetrachloride (CT) is often invoked to explain the product distribution resulting from its transformation. Radicals formed by reduction of CT presumably react with constituents of the surrounding milieu to give the observed product distribution. The patterns of transformation observed in this work were consistent with such a hypothesis. In cultures of Escherichia coli K-12, the pathways and rates of CT transformation were dependent on the electron acceptor condition of the media. Use of oxygen and nitrate as electron acceptors generally prevented CT metabolism. At low oxygen levels (approximately 1%), however, transformation of [14C]CT to 14CO2 and attachment to cell material did occur, in accord with reports of CT fate in mammalian cell cultures. Under fumarate-respiring conditions, [14C]CT was recovered as 14CO2, chloroform, and a nonvolatile fraction. In contrast, fermenting conditions resulted in more chloroform, more cell-bound 14C, and almost no 14CO2. Rates of transformation of CT were faster under fermenting conditions than under fumarate-respiring conditions. Transformation rates also decreased over time, suggesting the gradual exhaustion of transformation activity. This loss was modeled with a simple exponential decay term.

Aerobiosis↗
PubMed1970

Growth of Pseudomonas fluorescens with sodium maleate as a carbon source.

The growth of Pseudomonas fluorescens (ATCC 11150) on sodium maleate was observed, and the composition of the media was monitored in batch culture. Utilization of the maleate as the sole organic carbon source proceeded by stepwise conversion to fumarate and then to malate. Respiration rates of P. fluorescens on maleate, mixtures of maleate and fumarate salts, and mixtures of maleate and malate salts were measured. Complex effects, possibly due to a change in metabolic mechanism, were observed.

Acids↗
PubMed1974

Basic studies for continuous production of L-aspartic acid by immobilized Escherichia coli cells.

By using a column packed with immobilized Escherichia coli cells entrapped in a polyacrylamide gel lattice, conditions for continuous production of L-aspartic acid from ammonium fumarate were investigated. When a solution of 1 M ammonium fumarate (pH 8.5) containing 1 mM Mg(2+) was passed through the immobilized cell column at a flow rate of space velocity (SV) = 0.8 at 37 C, the highest rate of reaction was attained. From the column effluents, L-aspartic acid was obtained in good yield. The immobilized cell column was very stable.

Acrylamides↗
PubMed1973

Succinate oxidase in Neurospora.

Two kinetically distinct states of succinate oxidase have been detected in the mitochondria of Neruospora crassa. One state has a K(m) for succinate of 4.1 x 10(-3)m, and the other has a K(m) for succinate of 3.5 x 10(-4)m. The high K(m) state was found in freshly extracted mitochondria from either 20- or 72-hr mycelium. However, the succinate oxidase activity in mitochondria from 20-hr mycelium rapidly deteriorated in vitro, leaving a stable residual activity with the lower K(m) for succinate. Adenosine triphosphate (ATP) plus Mg(2+) stabilized the high K(m) state in these preparations. The high K(m) state of succinate oxidase was further characterized by a two- to threefold increase in activity over the pH range 6.6 to 8.0 and by classical competitive inhibition by fumarate and malonate. By contrast, the low K(m) state of succinate oxidase showed a relatively flat response to pH over the range 6.6 to 8.0 and a nonclassical pattern of inhibition by fumarate and malonate, as shown by nonlinear plots of reciprocal velocity versus reciprocal substrate concentration in the presence of inhibitor or reciprocal velocity versus inhibitor concentration at fixed substrate concentrations. The relationship of mycelial age to the in vitro stability of succinate oxidase is considered with reference to probable changes in the relative pool sizes of extra- and intramitochondrial ATP in response to changes in the rate of glycolysis.

Adenosine Triphosphate↗
PubMed1973

Glucose fermentation products in Ruminococcus albus grown in continuous culture with Vibrio succinogenes: changes caused by interspecies transfer of H 2 .

The influence of a H(2)-utilizing organism, Vibrio succinogenes, on the fermentation of limiting amounts of glucose by a carbohydrate-fermenting, H(2)-producing organism, Ruminococcus albus, was studied in continuous cultures. Growth of V. succinogenes depended on the production of H(2) from glucose by R. albus. V. succinogenes used the H(2) produced by R. albus to obtain energy for growth by reducing fumarate in the medium. Fumarate was not metabolized by R. albus alone. The only products detected in continuous cultures of R. albus alone were acetate, ethanol, and H(2). CO(2) was not measured. The only products detected in the mixed cultures were acetate and succinate. No free H(2) was produced. No formate or any other volatile fatty acid, no succinate or other dicarboxylic acids, lactate, alcohols other than ethanol, pyruvate, or other keto-acids, acetoin, or diacetyl were detected in cultures of R. albus alone or in mixed cultures. The moles of product per 100 mol of glucose fermented were approximately 69 for ethanol, 74 for acetate, 237 for H(2) for R. albus alone and 147 for acetate and 384 for succinate for the mixed culture. Each mole of succinate is equivalent to the production of 1 mol of H(2) by R. albus. Thus, in the mixed cultures, ethanol production by R. albus is eliminated with a corresponding increase in acetate and H(2) formation. The mixed-culture pattern is consistent with the hypothesis that nicotinamide adenine dinucleotide (reduced form), formed during glycolysis by R. albus, is reoxidized during ethanol formation when R. albus is grown alone and is reoxidized by conversion to nicotinamide adenine dinucleotide and H(2) when R. albus is grown with V. succinogenes. The ecological significance of this interspecies transfer of H(2) gas and the theoretical basis for its causing changes in fermentation patterns of R. albus are discussed.

Acetates↗
PubMed1973

Abolition of crypticity of Arthrobacter pyridinolis toward glucose and alpha-glucosides by tricarboxylic acid cycle intermediates.

Arthrobacter pyridinolis cannot grow on glucose as sole carbon source, although the cells possess catabolic enzymes of the Embden-Meyerhof and pentose phosphate pathways as well as a complete tricarboxylic acid cycle. Crypticity toward glucose is abolished by a period of growth in a medium containing malate, succinate, citrate, or fumarate in addition to glucose. Other carbon sources, which support as rapid growth as does malate (e.g. asparagine), do not enable the cells to use glucose. Malate, succinate, citrate, and fumarate abolish crypticity toward glucose only in the second phase of diauxic growth after the tricarboxylic acid cycle intermediate has been depleted. This sequence of events, first observed in growth curves, has been verified by experiments in which the incorporation of radioactive substrates into trichloroacetic acid-insoluble cellular material was followed. The tricarboxylic acid cycle intermediates which confer the ability to utilize glucose also enhance the utilization of the alphaglucosides sucrose and maltose. The mechanism whereby growth on certain tricarboxylic acid cycle intermediates confers the subsequent ability to grow on glucose is related to a transport system for glucose and alpha-glucosides. This transport system has been assayed by measuring the uptake of [1-(14)C]-2-deoxyglucose. Cells grown for varying periods of time in asparagine, asparagine plus glucose, or malate do not transport 2-deoxyglucose. Cells from malate-glucose cultures that are in the exponential phase of growth on glucose can transport 2-deoxyglucose. Transport of 2-deoxyglucose shows Michaelis-Menten kinetics with a K(m) of 2.9 x 10(-4) M. It is competitively inhibited by glucose, alpha-methylglucopyranoside, and maltose. The transport of 2-deoxyglucose is inhibited by cyanide, dinitrophenol, azide, and N-ethylmaleimide, but not by malonate or fluoride. No phosphoenolpyruvate: d-glucose phosphotransferase activity has been detected, and the 2-deoxyglucose transported into the cell is not phosphorylated.

Alcohol Oxidoreductases↗
PubMed1974

Effect of dicyclohexylcarbodiimide on growth and membrane-mediated processes in wild type and heptose-deficient mutants of Escherichia coli K-12.

The effects of N,N'-dicyclohexylcarbodiimide (DCCD) on the growth of Streptococcus faecalis, and on the growth, beta-galactosidase synthesis, and various membrane-mediated processes, were studied in wild-type Escherichia coli JE1011 and its lipopolysaccharide-defective mutant NS1. DCCD (0.1 mM) completely inhibited the growth of S. faecalis and E. coli NS1 but had little effect on strain JE1011. The same amount of DCCD with E. coli NS1, but not with E. coli JE1011, inhibited the induction of beta-galactosidase, increased the permeability of the cells to o-nitrophenyl-beta-d-galactoside without causing extensive cell lysis or release of ultraviolet-absorbing materials, and inhibited the oxidation of certain intermediates of the tricarboxylic acid cycle. Inhibition of the oxidation of malate, fumarate, and alpha-ketoglutarate by DCCD appeared to be at the level of the transport system for these compounds. Inhibition of the membrane-bound adenosine triphosphatase by DCCD was not entirely responsible for these effects, since oxidation of these substances, and transport of [(14)C]succinate and [(14)C]fumarate, was inhibited by DCCD in a mutant, N(144), which lacked adenosine triphosphatase activity. It is concluded that lipopolysaccharide forms a barrier to DCCD in wild-type E. coli, and that DCCD can inhibit several processes in the cell.

Adenosine Triphosphatases↗
PubMed1975

Amino acid transport in membrane vesicles of obligately anaerobic Veillonella alcalescens.

Membrane vesicles of Veillonella alcalescens, grown in the presence of L-lactate and KNO-3, actively transport amino acids under anaerobic conditions in the presence of several electron donors and the electron acceptor nitrate. The highest initial rates of uptake are obtained with L-lactate, followed by reduced nicotinamide adenine dinucleotide, glycerol-1-phosphate, formate, and L-malate.. The membrane vesicles contain the dehydrogenases for these electron donors, and these enzymes are coupled with nitrate reductase. In membrane vesicles from cells, grown in the presence of nitrate, the dehydrogenases are not coupled with fumarate reducatase, and anaerobic transport of amino acids does not occur with fumarate as electron acceptor. Under aerobic conditions none of the physiological electron donors can energize transport. However, a high rate of uptake is observed with the electron donor system ascorbate-phenazine metho-sulfate. This electron donor system also effectively energizes transport under anaerobicconditions in the presence of the electron acceptor nitrate.

Aerobiosis↗
PubMed1979

Electron acceptor taxis and blue light effect on bacterial chemotaxis.

Salmonella typhimurium and Escherichia coli from anaerobic cultures displayed tactic responses to gradients of nitrate, fumarate, and oxygen when the appropriate electron transport pathway was present. Such responses were named "electron acceptor taxis" because they are elicited by terminal electron acceptors. Mutant strains of S. typhimurium and E. coli were used to establish that functioning electron transport pathways to nitrate and fumarate are required for taxis to these compounds. Aerotaxis in S. typhimurium was blocked by 1.0 mM KCN, which inhibited oxygen uptake. Similarly, a functioning electron transport pathway was shown to be essential for the tumbling response of S. typhimurium and E. coli to intense light (290 to 530 nm). Some inhibitors and uncouplers of respiration were repellents of S. typhimurium. We propose that behavioral responses to light or electron acceptors involve electron transport-mediated perturbations of the proton motive force.

Anaerobiosis↗
PubMed1980

Regulation of hydrogenase activity in enterobacteria.

Proteus vulgaris, Escherichia coli, and Citrobacter freundii cells were devoid of hydrogenase activity when grown on complex medium or minimal medium plus glucose in the presence of saturating levels of dissolved oxygen. Anaerobically grown cells had appreciable hydrogenase activity. Cells grown anaerobically in the presence of CO (an inhibitor of hydrogenase) or nitrate (an electron acceptor) lacked hydrogenase activity. To make hydrogenase essential for anaerobic growth, cells were grown on fumarate, a nonfermentable carbon source. P. vulgaris and C. freundii evolved H2 gas under these conditions, and the hydrogenase-specific activity was 8 to 10 times greater than that in cells grown on glucose. Cell growth was inhibited by CO, and the cells grew but lacked hydrogenase activity when grown in the presence of nitrate. E. coli grew on fumarate plus H2, and the specific activity was five times greater than that in cells grown on glucose. Thus, hydrogenase activity is inducible and is expressed maximally when the enzyme is essential for cellular growth. Under conditions of growth where the enzyme would not be catalytically active, cells contain little active hydrogenase. Under anaerobic conditions where the enzyme is not essential for growth, the level of hydrogenase activity is intermediate.

Anaerobiosis↗
PubMed1982

Aerobic and anaerobic respiratory systems in Campylobacter fetus subsp. jejuni grown in atmospheres containing hydrogen.

Maximum growth of Campylobacter fetus subsp. jejuni, strain C-61, occurred when the cultures were incubated with shaking in atmospheres containing approximately 30% hydrogen, 5% oxygen, and 10% CO2. Suspensions of cells grown under these conditions consumed oxygen with formate as the substrate in the presence of 0.33 mM cyanide, which completely inhibited respiration with ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine and with lactate. Spectroscopic evidence with intact cells suggested that a form of cytochrome c, reducible with formate but not with lactate or ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine, can be reoxidized by a cyanide-insensitive system. Analysis of membranes from the cells showed high- and low-potential forms of cytochrome c, cytochrome b, and various enzymes, including hydrogenase, formate dehydrogenase, and fumarate reductase. The predominant carbon monoxide-binding pigment appeared to be a form of cytochrome c, but the spectra also showed evidence of cytochrome o. The membrane cytochromes were reduced by hydrogen in the presence of 2-heptyl-4-hydroxyquinoline-N-oxide at concentrations which prevented the reduction of cytochrome c with succinate as the electron donor. Reoxidation of the substrate-reduced cytochromes by oxygen was apparently mediated by cyanide-sensitive and cyanide-insensitive systems. The membranes also had hydrogen-fumarate oxidoreductase activity mediated by cytochrome b. We conclude that C. fetus jejuni has high- and low-potential forms of cytochrome which are associated with a complex terminal oxidase system.

Anaerobiosis↗
PubMed1998

The ms2io6A37 modification of tRNA in Salmonella typhimurium regulates growth on citric acid cycle intermediates.

The modified nucleoside 2-methylthio-N-6-isopentenyl adenosine (ms2i6A) is present in position 37 (adjacent to and 3' of the anticodon) of tRNAs that read codons beginning with U except tRNA(i.v. Ser) in Escherichia coli. In Salmonella typhimurium, 2-methylthio-N-6-(cis-hydroxy)isopentenyl adenosine (ms2io6A; also referred to as 2-methylthio cis-ribozeatin) is found in tRNA, most likely in the species that have ms2i6A in E. coli. Mutants (miaE) of S. typhimurium in which ms2i6A hydroxylation is blocked are unable to grow aerobically on the dicarboxylic acids of the citric acid cycle. Such mutants have normal uptake of dicarboxylic acids and functional enzymes of the citric acid cycle and the aerobic respiratory chain. The ability of S. typhimurium to grow on succinate, fumarate, and malate is dependent on the state of modification in position 37 of those tRNAs normally having ms2io6A37 and is not due to a second cellular function of tRNA (ms2io6A37)hydroxylase, the miaE gene product. We suggest that S. typhimurium senses the hydroxylation status of the isopentenyl group of the tRNA and will grow on succinate, fumarate, or malate only if the isopentenyl group is hydroxylated.

Chromosome Mapping↗
PubMed1998

Analysis of the novel benzylsuccinate synthase reaction for anaerobic toluene activation based on structural studies of the product.

Recent studies of anaerobic toluene catabolism have demonstrated a novel reaction for anaerobic hydrocarbon activation: the addition of the methyl carbon of toluene to fumarate to form benzylsuccinate. In vitro studies of the anaerobic benzylsuccinate synthase reaction indicate that the H atom abstracted from the toluene methyl group during addition to fumarate is retained in the succinyl moiety of benzylsuccinate. Based on structural studies of benzylsuccinate formed during anaerobic, in vitro assays with denitrifying, toluene-mineralizing strain T, we now report the following characteristics of the benzylsuccinate synthase reaction: (i) it is highly stereospecific, resulting in >95% formation of the (+)-benzylsuccinic acid enantiomer [(R)-2-benzyl-3-carboxypropionic acid], and (ii) active benzylsuccinate synthase does not contain an abstracted methyl H atom from toluene at the beginning or at the end of a catalytic cycle.

Anaerobiosis↗
PubMed1999

Identification and characterization of a two-component sensor-kinase and response-regulator system (DcuS-DcuR) controlling gene expression in response to C4-dicarboxylates in Escherichia coli.

The dcuB gene of Escherichia coli encodes an anaerobic C4-dicarboxylate transporter that is induced anaerobically by FNR, activated by the cyclic AMP receptor protein, and repressed in the presence of nitrate by NarL. In addition, dcuB expression is strongly induced by C4-dicarboxylates, suggesting the presence of a novel C4-dicarboxylate-responsive regulator in E. coli. This paper describes the isolation of a Tn10 mutant in which the 160-fold induction of dcuB expression by C4-dicarboxylates is absent. The corresponding Tn10 mutation resides in the yjdH gene, which is adjacent to the yjdG gene and close to the dcuB gene at approximately 93.5 min in the E. coli chromosome. The yjdHG genes (redesignated dcuSR) appear to constitute an operon encoding a two-component sensor-regulator system (DcuS-DcuR). A plasmid carrying the dcuSR operon restored the C4-dicarboxylate inducibility of dcuB expression in the dcuS mutant to levels exceeding those of the dcuS+ strain by approximately 1.8-fold. The dcuS mutation affected the expression of other genes with roles in C4-dicarboxylate transport or metabolism. Expression of the fumarate reductase (frdABCD) operon and the aerobic C4-dicarboxylate transporter (dctA) gene were induced 22- and 4-fold, respectively, by the DcuS-DcuR system in the presence of C4-dicarboxylates. Surprisingly, anaerobic fumarate respiratory growth of the dcuS mutant was normal. However, under aerobic conditions with C4-dicarboxylates as sole carbon sources, the mutant exhibited a growth defect resembling that of a dctA mutant. Studies employing a dcuA dcuB dcuC triple mutant unable to transport C4-dicarboxylates anaerobically revealed that C4-dicarboxylate transport is not required for C4-dicarboxylate-responsive gene regulation. This suggests that the DcuS-DcuR system responds to external substrates. Accordingly, topology studies using 14 DcuS-BlaM fusions showed that DcuS contains two putative transmembrane helices flanking a approximately 140-residue N-terminal domain apparently located in the periplasm. This topology strongly suggests that the periplasmic loop of DcuS serves as a C4-dicarboxylate sensor. The cytosolic region of DcuS (residues 203 to 543) contains two domains: a central PAS domain possibly acting as a second sensory domain and a C-terminal transmitter domain. Database searches showed that DcuS and DcuR are closely related to a subgroup of two-component sensor-regulators that includes the citrate-responsive CitA-CitB system of Klebsiella pneumoniae. DcuS is not closely related to the C4-dicarboxylate-sensing DctS or DctB protein of Rhodobacter capsulatus or rhizobial species, respectively. Although all three proteins have similar topologies and functions, and all are members of the two-component sensor-kinase family, their periplasmic domains appear to have evolved independently.

Amino Acid Sequence↗
PubMed1999

The steady-state internal redox state (NADH/NAD) reflects the external redox state and is correlated with catabolic adaptation in Escherichia coli.

Escherichia coli MC4100 was grown in anaerobic glucose-limited chemostat cultures, either in the presence of an electron acceptor (fumarate, nitrate, or oxygen) or fully fermentatively. The steady-state NADH/NAD ratio depended on the nature of the electron acceptor. Anaerobically, the ratio was highest, and it decreased progressively with increasing midpoint potential of the electron acceptor. Similarly, decreasing the dissolved oxygen tension resulted in an increased NADH/NAD ratio. As pyruvate catabolism is a major switch point between fermentative and respiratory behavior, the fluxes through the different pyruvate-consuming enzymes were calculated. Although pyruvate formate lyase (PFL) is inactivated by oxygen, it was inferred that the in vivo activity of the enzyme occurred at low dissolved oxygen tensions (DOT </= 1%). A simultaneous flux from pyruvate through both PFL and the pyruvate dehydrogenase complex (PDHc) was observed. In anaerobic cultures with fumarate or nitrate as an electron acceptor, a significant flux through the PDHc was calculated on the basis of the redox balance, the measured products, and the known biochemistry. This result calls into question the common assumption that the complex cannot be active under these conditions. In vitro activity measurements of PDHc showed that the cellular content of the enzyme varied with the internal redox state and revealed an activity for dissolved oxygen tension of below 1%. Whereas Western blots showed that the E3 subunit of PDHc (dihydrolipoamide dehydrogenase) did not vary to a large extent under the conditions tested, the E2 subunit (dihydrolipoamide acetyltransferase) amount followed the trend that was found for the in vitro PDHc activity. From this it is concluded that regulation of the PDHc is exerted at the E1/E2 operon (aceEF). We propose that the external redox state (measured as the midpoint potentials of those terminal acceptors with which the cell has sufficient capacity to react) is reflected by the internal redox state. The latter may subsequently govern both the expression and the activity of the two pyruvate-catabolizing enzymes.

Acetyltransferases↗
PubMed2000

Role of the tetraheme cytochrome CymA in anaerobic electron transport in cells of Shewanella putrefaciens MR-1 with normal levels of menaquinone.

Shewanella putrefaciens MR-1 possesses a complex electron transport system which facilitates its ability to use a diverse array of compounds as terminal electron acceptors for anaerobic respiration. A previous report described a mutant strain (CMTn-1) deficient in CymA, a tetraheme cytochrome c. However, the interpretation of the electron transport role of CymA was complicated by the fact that CMTn-1 was also markedly deficient in menaquinones. This report demonstrates that the depressed menaquinone levels were the result of the rifampin resistance phenotype of the parent of CMTn-1 and not the interruption of the cymA gene. This is the first report of rifampin resistance leading to decreased menaquinone levels, indicating that rifampin-resistant strains should be used with caution when analyzing electron transport processes. A site-directed gene replacement approach was used to isolate a cymA knockout strain (MR1-CYMA) directly from MR-1. While MR1-CYMA retained menaquinone levels comparable to those of MR-1, it lost the ability to reduce iron(III), manganese(IV), and nitrate and to grow by using fumarate as an electron acceptor. All of these functions were restored to wild-type efficacy, and the presence of the cymA transcript and CymA protein was also restored, by complementation of MR1-CYMA with the cymA gene. The requirement for CymA in anaerobic electron transport to iron(III), fumarate, nitrate, and manganese(IV) is therefore not dependent on the levels of menaquinone in these cells. This represents the first successful use of a suicide vector for directed gene replacement in MR-1.

Anaerobiosis↗