Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: EC:1.3.5.1 (succinate dehydrogenase)
8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, we examined whether exhaustive activation reduces succinate dehydrogenase (SDH) activity in diaphragm muscle fibers. In adult male rats (approximately 300 g), the costal diaphragm was excised and positioned in a chamber perfused with mammalian Ringer solution kept at 26 degrees C and oxygenated with 95% O2-5% CO2. The muscle was stimulated directly at 10 or 75 Hz in trains of 500 ms duration (1/s) for 8 min. An adjacent unstimulated segment of muscle served as control. The two muscle segments were frozen, and serial sections were stained for myofibrillar adenosinetriphosphatase activity after alkaline and acid preincubation to classify type I, IIa, and IIb fibers. The extent of glycogen utilization was also examined histochemically to confirm exhaustive activation of muscle fibers. SDH activity was quantified using a microdensitometric procedure implemented on an image-processing system. Exhaustive activation at both 10 and 75 Hz caused a significant decrease in SDH activity of all fiber types, with the decrease after 10-Hz stimulation being greater than that after 75-Hz stimulation. At both stimulation frequencies, type IIb fibers demonstrated the greatest decrease in SDH activity (36% after 10-Hz and 27% after 75-Hz stimulation), whereas type I and IIa fibers both displayed reductions of approximately 27 and approximately 19% after 10- and 75-Hz stimulation, respectively. The greater reduction of SDH activity in type IIb fibers indicates an inverse relationship between activation-induced reductions in SDH activity and fiber oxidative capacity.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Activation-induced reduction of SDH activity in diaphragm muscle fibers. 800 90

The lipophilic iron chelator 1,10-phenanthroline has been used in mechanistic studies on intracellular oxidant damage because iron is assumed to play a role in the endogenous formation of highly reactive oxygen species. This study shows that 1,10-phenanthroline has enzyme-modulatory properties in addition to its antioxidant activity. In rat hepatocytes, 1,10-phenanthroline caused inhibition of respiration and enhancement of cellular ATP content, pyruvate release and CO2 formation from glycerol resulting from a modulatory action of 1,10-phenanthroline on various enzymes involved in cellular energy metabolism. In intact mitochondria and in submitochondrial particles, oxygen consumption, complex I activity, and ATPase degradation are inhibited by 1,10-phenanthroline. In submitochondrial particles, complex II activity can also be suppressed by 1,10-phenanthroline. The purified cytosolic enzymes lactate dehydrogenase and glycerol-3-phosphate dehydrogenase are inhibited while purified glyceraldehyde-3-phosphate dehydrogenase is activated by 1,10-phenanthroline. The results suggest that 1,10-phenanthroline modulates various enzyme activities linked to cellular energy metabolism and that this property must be taken into account when using 1,10-phenanthroline as a tool in experiments on oxidant effects in cells.
...
PMID:Ortho-phenanthroline modulates enzymes of cellular energy metabolism. 865 62

The dimethyl esters of succinic acid (SAD) and glutamic acid (GME) were found to be efficiently metabolized in colon carcinoma cells of the Caco-2 line. The rate of [1,4-14C]SAD and [2,3-14C]SAD conversion to radioactive acidic metabolites, CO2, amino acids, pyruvic acid, and lactic acid suggested that the catabolism of the ester-derived succinic acid occurred mainly through the sequence of reactions catalyzed by succinate dehydrogenase, fumarase, and the malic enzyme. This coincided with a marked sparing action of SAD on the utilization of D-[2-(3)H]glucose and D-[5-(3)H]glucose and generation of 14C-labeled acid metabolites, CO2, and lactic acid from D-[U-14C]glucose by the enterocytes. Likewise, the conversion of [U-14C]GME to 14C-labeled amino acids, its oxidation compared with that of [1-(14)C]GME, and the production of NH4+ in the absence or presence of GME indicated efficient catabolism of the latter ester. Like SAD, GME decreased the utilization of D-[5-(3)H]glucose and generation of 14C-labeled acidic metabolites, pyruvate, and CO2 from D-[6-(14)C]glucose, while increasing the generation of 14C-labeled amino acids from the labeled hexose. The oxidation of D-[6-(14)C]glucose was even more severely inhibited by GME. In normal rat intestinal cells, SAM, SAD, and GME also exerted a marked sparing action on D-[U-14C]glucose oxidation. The present findings suggest, therefore, that these esters could possibly be used to sustain ATP generation in intestinal cells.
...
PMID:Nutritional efficiency of succinic acid and glutamic acid dimethyl esters in colon carcinoma cells. 896 98

In vivo, bicarbonate can affect proximal tubule intermediary metabolism, including gluconeogenesis, ammoniagenesis and maintenance of the mitochondrial substrate supply. In vitro, rabbit proximal tubule cells (RPTC) in primary culture revert from gluconeogenesis to glycolysis and their mitochondrial metabolism remains lower than in vivo. To determine whether the bicarbonate buffer system could have an effect on these deregulations, RPTC in primary culture grown in the absence of insulin and glucose in the culture medium were developed either with the standard sodium bicarbonate buffer with 5% CO2 or with a Hepes hydrogen ion buffer in the presence of 0.5% CO2. Duration of the bicarbonate-free cultures was increased until at least day 17 after seeding, compared with day 11 in bicarbonate-buffered cultures. As could be expected, succinate dehydrogenase activity remained stable as a function of time in bicarbonate-free cultures while an early marked decrease of this activity occurred from seeding in cultures developed in the presence of bicarbonate buffer. Compared to bicarbonate-buffered cells, higher phosphoenolpyruvate carboxykinase activity concomitant with lower intracellular lactate dehydrogenase activity was observed in cultures developed in the absence of bicarbonate, which is indicative of closer carbohydrate metabolism orientation to the in vivo situation for RPTC. Immunofluorescence staining of RPTC with monoclonal antibodies directed to neutral endopeptidase (NEP), and dipeptidyl-peptidase IV (DPP II) showed similar extensive labelling with DPP and NEP in both culture conditions. Confocal microscopy analysis of NEP subcellular distribution, showed exclusive targetting of NEP to the apical plasma membranes. In both models, cAMP production was stimulated by parathyroid hormone and unaffected by arginine vasopressin. In conclusion, bicarbonate withdrawal from the culture medium (without changing the pH of the medium) allows a marked improvement of mitochondrial capacity and carbohydrate metabolism pattern without any loss of differentiated properties.
...
PMID:Effects of the medium HCO3-/CO2 buffer system on differentiation and intermediary metabolism properties of rabbit proximal tubule cells in primary culture. 897 88

A modified procedure is developed for isolation of highly purified succinate-ubiquinone reductase from Escherichia coli NM256 containing a cloned sdh operon in a multicopy plasmid. Succinate-ubiquinone reductase is solubilized from the membrane by polyoxyethylene-9-lauryl ether and purified by DEAE-Sepharose CL-6B column chromatography. The isolated reductase is resolved into a reconstitutively active, two-subunit succinate dehydrogenase and a two-subunit membrane anchoring protein fraction (the SdhC-SdhD fraction) by alkaline (pH 10.2) treatment of the reductase in the presence of 1 M urea, followed by DEAE-Sepharose CL-6B column chromatography under anaerobic conditions. Isolated succinate dehydrogenase and the SdhC-SdhD fraction alone show no succinate-ubiquinone reductase activity. However, when a given amount of the SdhC-SdhD fraction is mixed with varying amounts of succinate dehydrogenase or vice versa succinate-ubiquinone reductase activity increases as the amount of succinate dehydrogenase or the SdhC-SdhD fraction added increases. Maximum reconstitution is obtained when the weight ratio of succinate dehydrogenase to the SdhC-SdhD fraction reaches 5.26. This ratio is slightly higher than the calculated value of 3.37, obtained by assuming 1 mol of succinate dehydrogenase reacts with 1 mol of SdhC and SdhD. The isolated SdhC-SdhD fraction contains 35 nmol cytochrome b556/mg protein. Unlike mitochondrial cytochrome b560, the cytochrome b556 is reducible by succinate in the isolated and complex forms. Furthermore, cytochrome b556 in the isolated SdhC-SdhD fraction has absorption properties, carbon monoxide reactivity, and EPR characteristics similar to those of cytochrome b556 in intact succinate-ubiquinone reductase, indicating that its heme environments are not affected by the presence of succinate dehydrogenase. However, the redox potential of cytochrome b556 in the SdhC-SdhD fraction (22 mV) increases slightly when complexed with succinate dehydrogenase (34 mV). No hybrid succinate-ubiquinone reductase is formed from mitochondrial QPs (the membrane-anchoring protein fraction of bovine heart mitochondrial succinate-ubiquinone reductase) and E. coli succinate dehydrogenase or vice versa. However, the cytochrome b556 in E. coli SdhC-SdhD fraction is reducible by succinate in the presence of mitochondrial succinate dehydrogenase, and the rate of cytochrome b556 reduction correlates with the reconstitutive activity of the mitochondrial succinate dehydrogenase.
...
PMID:Resolution and reconstitution of succinate-ubiquinone reductase from Escherichia coli. 909 98

Natronobacterium pharaonis, an aerobic haloalkaliphilic archaebacterium, expresses high concentrations of redox proteins as do alkaliphilic eubacteria. The first redox protein characterized from N. pharaonis was halocyanin [Scharf, B., & Engelhard, M. (1993) Biochemistry 32, 12894-12900], a small blue copper protein. It is a peripheral membrane protein and is conjectured to function in a manner similar to plastocyanin. In the present work, the respiratory chain is further elucidated and the purification and characterization of the most abundant components cytochrome bc and cytochrome ba3 from the membrane fraction are described. The cytochrome bc complex consists of a 14 and an 18 kDa subunit in a 1:1 ratio, with heme c bound to the larger polypeptide. An Fe-S subunit similar to that found in eukaryotic bc complexes has not yet been identified. The second membrane complex carries two different heme groups of the ba3-type as well as copper. It contains two subunits of 36 and 40 kDa. This cytochrome ba3 binds carbon monoxide, a feature common to terminal oxidases. There is no spectroscopic evidence for a second terminal oxidase; hence, under the growth conditions chosen the respiratory chain of N. pharaonis appears to be unbranched. In addition to these cytochromes, a succinate dehydrogenase which is solubilized from the membrane by detergents was isolated. A cytochrome c which was isolated from the cytosol has an unusually high molecular weight and a redox potential of -142 mV. A second cytosolic protein, ferredoxin, was purified to homogeneity. A comparison of the redox potentials of the isolated proteins with those obtained from the native membrane allows the construction of a possible electron transfer chain.
...
PMID:Electron transfer proteins from the haloalkaliphilic archaeon Natronobacterium pharaonis: possible components of the respiratory chain include cytochrome bc and a terminal oxidase cytochrome ba3. 910 54

The growth of the syntrophic propionate-oxidizing bacterium strain MPOB in pure culture by fumarate disproportionation into carbon dioxide and succinate and by fumarate reduction with propionate, formate or hydrogen as electron donor was studied. The highest growth yield, 12.2 g dry cells/mol fumarate, was observed for growth by fumarate disproportionation. In the presence of hydrogen, formate or propionate, the growth yield was more than twice as low: 4.8, 4.6, and 5.2 g dry cells/mol fumarate, respectively. The location of enzymes that are involved in the electron transport chain during fumarate reduction in strain MPOB was analyzed. Fumarate reductase, succinate dehydrogenase, and ATPase were membrane-bound, while formate dehydrogenase and hydrogenase were loosely attached to the periplasmic side of the membrane. The cells contained cytochrome c, cytochrome b, menaquinone-6 and menaquinone-7 as possible electron carriers. Fumarate reduction with hydrogen in membranes of strain MPOB was inhibited by 2-(heptyl)-4-hydroxyquinoline-N-oxide (HOQNO). This inhibition, together with the activity of fumarate reductase with reduced 2,3-dimethyl-1,4-naphtoquinone (DMNH2) and the observation that cytochrome b of strain MPOB was oxidized by fumarate, suggested that menequinone and cytochrome b are involved in the electron transport during fumarate reduction in strain MPOB. The growth yields of fumarate reduction with hydrogen or formate as electron donor were similar to the growth yield of Wolinella succinogenes. Therefore, it can be assumed that strain MPOB gains the same amount of ATP from fumarate reduction as W. succinogenes, i. e. 0.7 mol ATP/mol fumarate. This value supports the hypothesis that syntrophic propionate-oxidizing bacteria have to invest two-thirds of an ATP via reversed electron transport in the succinate oxidation step during the oxidation of propionate. The same electron transport chain that is involved in fumarate reduction may operate in the reversed direction to drive the energetically unfavourable oxidation of succinate during syntrophic propionate oxidation since (1) cytochrome b was reduced by succinate and (2) succinate oxidation was similarly inhibited by HOQNO as fumarate reduction.
...
PMID:Investigation of the fumarate metabolism of the syntrophic propionate-oxidizing bacterium strain MPOB. 953 36

The operation of the citric acid cycle of Escherichia coli during nitrate respiration (anoxic conditions) was studied by measuring end products and enzyme activities. Excretion of products other than CO2, such as acetate or ethanol, was taken as an indication for a non-functional cycle. From glycerol, approximately 0.3 mol acetate was produced; the residual portion was completely oxidized, indicating the presence of a partially active citric acid cycle. In an arcA mutant devoid of the transcriptional regulator ArcA, glycerol was completely oxidized with nitrate as an electron acceptor, demonstrating derepression and function of the complete pathway. Glucose, on the other hand, was excreted mostly as acetate by the wild-type and by the arcA mutant. During growth on glucose, but not on glycerol, activities of succinate dehydrogenase and of 2-oxoglutarate dehydrogenase were missing nearly completely. Thus, the previously described strong repression of the citric acid cycle during nitrate respiration occurs only during growth on glucose and is the effect of anaerobic and, more important, of glucose repression. In Pseudomonas fluorescens (but not Pseudomonas stutzeri), a similar decrease of citric acid cycle function during anaerobic growth with nitrate was found, indicating a broad distribution of this regulatory principle.
...
PMID:Functional citric acid cycle in an arcA mutant of Escherichia coli during growth with nitrate under anoxic conditions. 963 97

The succinate dehydrogenase complex of the thermoacidophilic archaeon Acidianus ambivalens was investigated kinetically and by EPR spectroscopy in its most intact form, i.e., membrane bound. Here it is shown that this respiratory complex has an unusual iron-sulfur cluster composition in respect to that of the canonical succinate dehydrogenases known. The spectroscopic studies show that center S3, the succinate responsive [3Fe-4S]1+/0 cluster of succinate dehydrogenases, is not present in membranes prepared from aerobically grown A. ambivalens, nor in partially purified complex fractions. On the other hand, EPR features associated to the remaining centers, clusters S1 ([2Fe-2S]1+/2+) and S2 ([4Fe-4S]2+/1+), could be observed. Similar findings were made in other archaea, namely Acidianus infernus and Sulfolobus solfataricus. Kinetic investigations showed that the A. ambivalens enzyme is reversible, capable of operating as a fumarate reductase - a required activity if this obligate autotroph performs CO2 fixation via a reductive citric acid cycle. Sequencing of the sdh operon confirmed the spectroscopic data. Center S3 ([3Fe-4S]) is indeed replaced by a second [4Fe-4S] center, by incorporation of an additional cysteine, at the cysteine cluster binding motif (CxxYxxCxxxC-->CxxCxxCxxxC). Genomic analysis shows that genes encoding for succinate dehydrogenases similar to the ones here outlined are also present in bacteria, which may indicate a novel family of succinate/fumarate oxidoreductases, spread among the Archaea and Bacteria domains.
...
PMID:The unusual iron sulfur composition of the Acidianus ambivalens succinate dehydrogenase complex. 1021 59

Ten patients with perennial allergic rhinitis were subjected to CO2 laser turbinectomy. Tiny (1 mm3) biopsy specimens were taken at the time of surgery and 1 month thereafter. The biopsy specimens were processed for transmission electron microscopy. Also, the activity of succinic dehydrogenase and cholinesterase enzymes was measured. The study showed that laser turbinectomy was followed by reduction in the number and activity of the glandular acini in the laser-treated areas. This reduction is ascribed to the local destructive effect of laser energy on the glandular acini and on the surrounding cholinergic nerve fibers. The enzymatic activity of the cholinergic nerve fibers themselves, however, did not diminish, indicating that laser surgery has no inhibitory effect on the local allergic reaction.
...
PMID:Laser surgery for allergic rhinitis: the effect on seromucinous glands. 1022 3


<< Previous 1 2 3 4 5 6 7 8 Next >>

---