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)

This study reports on the distribution of bicarbonate-stimulated ATPase in rat intestinal epithelial cells. Brush-border membranes and basolateral membranes were separated from each other and from mitochondrial and other intracellular membranes by differential and density gradient centrifugation. Bicarbonate-sensitive ATPase activity followed the mitochondrial marker succinic dehydrogenase closely throughout all the centrifugation steps. The low HCO3--ATPase activity in purified brush-border and basolateral plasma membranes could be accounted for quantitatively by the small mitochondrial contamination. Consequently, there are no grounds for postulating that this enzyme has a direct role in H+ or HCO3- transport across the rat small intestine.
...
PMID:Distribution of bicarbonate-stimulated ATPase in rat intestinal epithelium. 14 Jan 75

Differential centrifugation of rat small intestinal homogenates produced a crude brush border (BB) fraction that was enriched 15-fold for the marker enzymes, alkaline phosphatase and sucrase; contamination with mitochondrial enzymes, monoamine oxidase and succinate dehydrogenase, was minimal. ATP hydrolysis by this BB fraction was stimulated by addition of several anions to the incubation medium: HCO3 and Cl were equally effective in this regard, with NO3, NO2, SO4, and acetate being less stimulatory. SCN and CNO inhibited ATPase activity, whereas the divalent anion SO3 was stimulatory at low concentrations (less than 25 mM) but inhibitory at 100 mM. Maximum anion stimulation was observed at a Mg concentration of 0.5 mM, and pH optimum was 8.5. Kinetic analysis showed that HCO3 increased the Vmax without altering the Km for ATP; the Ka for this effect of HCO3 was 35 mM. This enzyme activity was completely inhibited by 20 mM L-phenylalanine, 10 mM L-cysteine, and 3 mM EDTA, compounds that also inhibited intestinal alkaline phosphatase. These results demonstrate the presence of anion-stimulated ATPase activity in rat small intestinal brush border and suggest that this activity may be related to intestinal alkaline phosphatase. The role of this enzyme in intestinal transport is not known, but could relate to the regulation of intestinal absorption and secretion.
...
PMID:Anion-stimulated ATPase activity of brush border from rat small intestine. 15 3

Rat kidney was studied histochemically and in electron microscope during administration of lithium carbonate for 14 days in doses of 4 mmol/l. Morphological examination demonstrated signs of damage exclusively to the epithelial cells in the proximal tubule. Histochemical examination demonstrated a major reduction of the reactions for succinate dehydrogenase and cytochrome oxidase. No difference was found in the intensity of the reaction for alkaline phosphatase and Ca-ATPase during lithium treatment as compared to controls. Additional observation demonstrated, only in histological examination, an increased number of cells of the macula densa.
...
PMID:Ultrastructural and histochemical assessment of proximal renal tubule in rats during administration of lithium carbonate. 251 37

Isolated rat kidney cortex mitochondria were incubated at pH 7.4 in the presence or absence of a CO2/bicarbonate buffer (28 mM) to investigate the pH-independent role of bicarbonate on glutamine and glutamate metabolism. Changes in the concentration of key intermediates and products during the incubations were used to calculate metabolite flux rates through specific mitochondrial enzymes. With 1 mM glutamine and 2 mM glutamate as substrates, bicarbonate caused an inhibition of glutamate oxalacetate transaminase flux and a stimulation of glutamate deamination. The same effects were also produced with addition of either aminooxyacetate or malonate. These effects of bicarbonate were prevented when 0.2 mM malate was included as an additional substrate. Bicarbonate ion was identified as a potent competitive inhibitor of rat kidney cortex succinate dehydrogenase. These results indicate that aminooxyacetate, malonate, and bicarbonate all act to stimulate glutamate deamination through a suppression of glutamate transamination, and that the control by transamination of glutamate deamination is due to alterations in alpha-ketoglutarate metabolism. In contrast, in mitochondria incubated with glutamine in the absence of glutamate, bicarbonate was found to inhibit glutamate dehydrogenase flux. This effect was found to be due in part to the lower intramitochondrial pH observed in incubations with bicarbonate. These findings indicate that bicarbonate ion, independent of pH, may have an important regulatory role in renal glutamine and glutamate metabolism.
...
PMID:Effect of bicarbonate on glutamine and glutamate metabolism by rat kidney cortex mitochondria. 286 61

High HCO3(-)-ATPase activity is known to exist in mitochondria of renal tubular cells. In brush border membrane (BBM) preparations of proximal tubules such an anion-stimulated enzyme was also found. However, these preparations always contained mitochondrial markers. The putative localization and the role of this ATPase in BBM is still controversial. Some authors consider the HCO3(-)-ATPase in the BBM to be a mitochondrial contamination; others attribute to this ATPase a key role in H+ transport in the proximal tubule. To reinvestigate this problem, BBMs from rat kidney cortex were isolated by a simple, rapid (1.5-h) Ca2+-precipitation method, yielding a BBM fraction enriched 12.4-fold with respect to the marker enzyme leucine aminopeptidase (LAP). There was no basolateral Na+-K+-ATPase and no mitochondrial succinate dehydrogenase detectable. Cytochrome c oxidase was drastically reduced to 7 +/- 1% of that observed in the homogenate (TH). The activity of HCO3(-)-ATPase in the BBM fraction was 19 +/- 4 IU/g protein, i.e., 27% that of the homogenate. As sonication of the TH exclusively increases the activity of HCO3(-)-ATPase, its relative activity was 7.5% and thus equal to that of the mitochondrial marker. In many BBM preparations no HCO3(-)-ATPase was detectable. In those BBM preparations in which traces of HCO3(-)-ATPase were found, this activity coincided with that of cytochrome c oxidase in the respective preparation. There was a constant activity ratio of cytochrome c oxidase/HCO3(-)-ATPase in the TH, BBM, and pellet 1. The activity of HCO3(-)-ATPase in BBM did not depend on the activity of LAP.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Evidence for mitochondrial origin of the HCO3(-)-ATPase in brush border membranes of rat proximal tubules. 298 70

Basal-lateral and brush border membranes from pig kidney cortex were prepared by differential centrifugation followed by free-flow electrophoresis. In each type of membrane, azide-insensitive, low-affinity Ca2+-ATPase and Mg2+-ATPase activities are demonstrated. A comparative study for both membranes further reveals the following analogies between these ATPases: (a) they show maximal activity between pH 8 and 8.5; (b) they exhibit Km values for Ca-ATP or Mg-ATP in the millimolar range and have a comparable low substrate specificity; (c) they are insensitive to 10 microM of vanadate, N,N'-dicyclohexylcarbodiimide, e diethylstilbestrol, quercetin, harmaline and amiloride. The partial inhibition by 1 mM of the various compounds is rather aspecific. In view of these similarities it is concluded that only one enzyme entity is responsible for the activity which is measured in both membrane types. The HCO3-stimulated Mg2+-ATPase activity in pig kidney cortex was also studied. This enzyme, however, is clearly of mitochondrial origin since the HCO3-stimulation coincides with the distribution profile of succinate dehydrogenase, a mitochondrial marker; and since it is inhibited by azide.
...
PMID:An azide-insensitive low-affinity ATPase stimulated by Ca2+ or Mg2+ in basal-lateral and brush border membranes of kidney cortex. 316 26

Anion exchange plays an important role in renal ion transport and acidification. To further understand the molecular nature of renal epithelial anion exchange, we used a monoclonal antibody to the membrane domain (52 kDa) of human erythrocyte band 3 protein to immunocytochemically search for this polypeptide in the rabbit kidney. In cryostat sections, a subpopulation of cells in the cortical and outer medullary collecting tubules showed immunoreactivity; labeling was restricted to the basolateral membrane. Proximal tubules and thick and thin limbs of Henle showed no immunoreactivity. Approximately 11% of cells in the cortical, but 43% of cells in the medullary, collecting tubule were positive for band 3. To determine the type of cells that were band 3 positive, mitochondria-rich (intercalated) cells were identified by their positive histochemical staining for succinic dehydrogenase activity and by their ability to bind peanut lectin at the apical membrane. In the cortical collecting tubule, the majority of mitochondria-rich cells bound peanut lectin but were band 3 negative; the remainder were band 3 positive but lectin negative. This distribution was reversed in the inner stripe of the outer medulla: all mitochondria-rich cells were band 3 positive and lectin negative. Thus mitochondria-rich cells are of at least two types, each of which has a distinct axial distribution pattern. Given available information about in vitro HCO3 transport properties of rabbit collecting tubules, it is likely that the lectin-positive, band 3-negative mitochondria-rich cells secrete HCO3, whereas the lectin-negative, band 3-positive cells reabsorb HCO3 (secrete H).
...
PMID:Two types of collecting duct mitochondria-rich (intercalated) cells: lectin and band 3 cytochemistry. 352 79

Analytical subcellular fractionation of tissue whole homogenates and microanalysis of organelle marker enzymes were used to study the activity and subcellular localization of enzymes implicated in HCO3 secretion in rat duodenal and gastric antral mucosae. The following organelles, characterized by their marker enzymes, were located in the density gradients: cytosol (lactate dehydrogenase), plasma membrane (5'-nucleotidase), peroxisomes (catalase), mitochondria (succinate dehydrogenase), endoplasmic reticulum (Tris-resistant alpha-glucosidase), lysosomes (N-beta-acetylglucosaminidase), and brush-border membrane (Zn2+-resistant alpha-glucosidase and alkaline phosphatase). Compared with gastric antrum, rat duodenal mucosa contained over twice the activity of HCO3-ATPase and of Na+-K+-ATPase but less than one-tenth the activity of carbonic anhydrase. Duodenal HCO3-ATPase activity was observed in both mitochondrial and brush-border membrane fractions, whereas antral HCO3-ATPase activity was confined to mitochondria. Na+-K+-ATPase activity was found largely in the basolateral membrane (duodenum) and plasma membrane (antrum). In both tissues carbonic anhydrase activity was localized to the cytosolic fraction. These observations offer further evidence that differing biochemical mechanisms underlie HCO3 secretion by gastric and duodenal epithelia.
...
PMID:Activities and subcellular localizations of enzymes implicated in gastroduodenal bicarbonate secretion. 608 73

The possible role of Mg2+-HCO3-ATPase, carbonic anhydrase and several other enzymes in rat intestinal mucosa as mediators of the action of aldosterone has been examined. The small-intestinal tract was cut into seven segments, 15 cm each in length and the mucosa was scraped off, homogenized in 50 mM D-mannitol-2 mM Tris-HCl buffer (pH 7.1), differentially fractionated and a crude brush border was obtained. The mucosa from the colon and rectum was combined and used as the large-intestinal sample. Five days after the adrenalectomy, activities of brush border Mg2+-HCO3-ATPase and supernatant carbonic anhydrase from the upper small intestine decreased to about 60 and 40% of normal values, respectively. Activities of Na+-K+-ATPase, beta-glycerophosphatase and succinate dehydrogenase were all decreased. Two and 4 h after i.p. injection of aldosterone (40 micrograms/kg) to adrenalectomized rats, all enzyme activities increased except for Na+-K+-ATPase in the upper small intestine. In contrast, Mg2+-HCO-3-ATPase and carbonic anhydrase activities were unchanged 3 h after i.p. injection of dexamethasone (200 micrograms and 1 mg/kg). The activation of both Mg2+-HCO3-ATPase and carbonic anhydrase by a single injection of aldosterone was blocked by pretreatment with cycloheximide (1 mg/kg). These results suggest that aldosterone may induce the synthesis of enzyme proteins in the intestinal mucosa.
...
PMID:Brush border Mg2+-HCO-3-ATPase, supernatant carbonic anhydrase and other enzyme activities isolated from rat intestinal mucosa: effect of adrenalectomy and aldosterone administration. 613 8

The intracellular localization of a Cl--HCO3--ATPase, which is inhibited by SCN-, was studied in the gills of the rainbow trout, Salmo gairdneri. This activity can be measured in the absence of contamination by mitochondria (i.e., in the absence of succinate dehydrogenase or cytochrome c oxidase activities). The distribution of the 5'-nucleotidase and of the ATPase stimulated by Cl- and HCO3- after sucrose density gradient centrifugation of the microsomal fraction was compared. Because those activities cannot be separated, it is postulated that the anion-stimulated ATPase is located in the plasma membrane. The activation of this microsomal anion ATPase by chloride has been studied extensively. The possible role of the Cl--HCO3--ATPase of trout gills in the Cl-/HCO3- exchange and in the regulation of the internal acid-base balance is discussed.
...
PMID:Cl--HCO3--ATPase in gills of the rainbow trout: evidence for its microsomal localization. 644 66


1 2 Next >>

---