Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cochlear microphonics and succinic dehydrogenase (SDH) activity of the hair cells during anoxia were studied in guinea pigs. After injection of the glucose-glucose oxidase mixture into the cerebellomedullary cistern, the deprivation of the oxygen tension in CSF and perilymph was measured in different time courses. In CSF, oxygen tension was reduced to zero within 60 min while in perilymph the maximal reduction was about a half the original level. The cochlear microphonics responded well to the oxygen tension deprivation in the perilymph. SDH activity, particularly in the outer hair cells was quite parallel to the oxygen tension in perilymph and also to the behavior of the cochlear microphonics. The present results indicate a close relationship between the electrophysiological and histochemical findings and that cochlear microphonics represent the function of the outer hair cells only.
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PMID:Cochlear microphonics and SDH activity in the hair cells under anoxia. 98 31

Two-dimensional gel electrophoresis (2-D) was used to resolve the plasma membrane proteins from cultured human retinal pigment epithelial cells. The cells were metabolically labeled either with [35S]methionine to reveal proteins in general or with [3H]glucosamine or [3H]fucose which are more specific for glycoprotein visualization. The cell surface proteins were also iodinated, using the lactoperoxidase--glucose oxidase technique. These labeled membranes were separate into plasma membrane-enriched fractions by subjecting the water-shocked postnuclear supernatant to a discontinuous sucrose-density gradient. The five resulting membrane fractions were assayed for protein, RNA (microsomes), galactosyltransferase (Golgi membranes), 5'-nucleotidase (plasma membranes), and succinate dehydrogenase (mitochondrial membranes) and were examined by electron microscopy. The plasma membranes were enriched with minimal contamination at the 0.6-0.85 M (F2) and 0.85-1.0 M (F3) sucrose interfaces based on these biochemical and morphological criteria. Examination of 2-D autoradiographic profiles of F2 and F3 showed that approximately 180 proteins or protein subunits had incorporated [35S]methionine. Certain proteins were also labeled by [3H]glucosamine and [3H]fucose, and surface-labeled by iodination. This was especially true of 17 different high-molecular-weight (43-139 X 10(3) MW) very acidic glycoproteins which formed a constellation of spots. These glycoproteins, as well as others, were also seen in the whole-cell acidic glucosamine-labeled 2-D profiles, where about 150 proteins were detected. A total of 39 proteins were catalogued, of which 34 were detectable in the plasma membrane-enriched fractions. The results show that the use of subcellular fractionation, specific precursors, and labeling techniques aids in the detection and characterization of minor proteins in 2-D gels.
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PMID:Isolation and characterization of plasma membrane proteins of cultured human retinal pigment epithelium. 243 67

The distribution of basal and of H2O2-stimulated cyclooxygenase activity in the primary fractions of rat brain homogenates and in the subfractions of crude mitochondrial fraction was studied. For comparison, the localization of H2O2-generating monoamine oxidase (MAO) as well as that of the mitochondrial marker succinate dehydrogenase (SDH) was also examined. H2O2 was generated by MAO using 5 x 10(-4) M noradrenaline (NA) or 2 x 10(-4) M 2-phenylethylamine (PEA) as substrates, or by 25 micrograms glucose oxidase (GOD) per ml in the presence of 1 mM glucose. For nonstimulated (basal) cyclooxygenase, the relative specific activity (RSA) was high in microsomes (1.79) and in the free mitochondria-containing subfraction of the crude mitochondrial fraction (1.94). Parallel distribution of MAO and H2O2-stimulated cyclooxygenase was observed in all fractions studied in the presence of NA. The highest RSA was found in the purified mitochondria for both enzymes (1.85 for MAO and 1.97 for H2O2-stimulated cyclooxygenase). The enrichment of SDH (RSA = 2.21) indicated a high concentration of mitochondria in this fraction. The same distribution of H2O2-stimulated cyclooxygenase was obtained when, instead of the MAO-NA system, hydrogen peroxide was generated by GOD in the presence of glucose. H2O2 generated by deamination of NA or PEA by MAO, or during the enzymatic oxidation of glucose by GOD, caused a threefold increase in mitochondrial endoperoxide formation. Indomethacin (2 x 10(-4) M), catalase (50 micrograms/ml), and pargyline (2 x 10(-4) M) eliminated the MAO-dependent mitochondrial synthesis of PG endoperoxides. The GOD-dependent cyclooxygenase activity in this fraction was abolished by indomethacin or catalase, but not by pargyline. The results show the existence of a mitochondrial cyclooxygenase in brain tissue. The enzyme is sensitive to H2O2 and produces prostaglandin endoperoxides from an endogenous source of arachidonic acid. The identical localization of H2O2-producing MAO and H2O2-sensitive cyclooxygenase suggests a possible coupling between monoamine and arachidonic acid metabolism.
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PMID:Evidence for the localization of hydrogen peroxide-stimulated cyclooxygenase activity in rat brain mitochondria: a possible coupling with monoamine oxidase. 640

The reduction of manganese(III) meso-tetrakis((N-ethyl)pyridinium-2-yl)porphyrin (MnTE-2-PyP) to manganese(II) was catalyzed by flavoenzymes such as xanthine oxidase and glucose oxidase, and by Complex I and Complex II of the mitochondrial electron transport chain. The reduced manganese porphyrin has been previously shown to react rapidly with superoxide and carbonate radical anion. Herein, we describe the reaction of a reduced manganese porphyrin with peroxynitrite that proceeds as a two-electron process, has a rate constant greater than 7 x 10(6) M(-1) s(-1) (at pH 7.25 and 37 degrees C), and produces nitrite and the Mn(IV)Porphyrin. The Mn(II)/Mn(IV) redox cycle was used to divert peroxynitrite from the inactivation of succinate dehydrogenase. In a typical experiment, 5 microM MnTE-2-PyP in the presence of excess succinate was able to protect the succinate dehydrogenase and succinate oxidase activities of submitochondrial particles challenged with a cumulative dose of 140 microM peroxynitrite infused in the course of 2 h. Other MnPorphyrins that are reduced more slowly do not provide as much protection underscoring the rate limiting character of the reduction step. The data presented here serve to rationalize the pharmacological action of MnPorphyrins as peroxynitrite reduction catalysts in vivo and opens avenues for the development of MnPorphyrins to protect mitochondria from oxidative damage.
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PMID:Reduction of manganese porphyrins by flavoenzymes and submitochondrial particles: a catalytic cycle for the reduction of peroxynitrite. 1684 31