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

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Homogenates of HTC cells have been fractionated by differential centrifugation (in four particulate fractions: N, M, L, P, and a supernatant S) or isopycnic banding in linear sucrose gradients. On this basis, the following subcellular organelles may be characterized: (i) Mitochondria, detected by cytochrome oxidase and succinodehydrogenase, are collected in the M and L fractions, and equilibrate, as a narrow band, at a median buoyant density of 1.18 g/cm3. (ii) Lysosomes, detected by the latent hydrolases beta-glycerophosphatase and N-acetyl-beta-glucosaminidase, are largely sedimented in the M and L fractions, and display a broad density distribution pattern with a median value of 1.17 g/cm3. This density is decreased or increased after cultivation of the cells in presence of Triton WR-1339 or Dextran 500, respectively. The behavior of cathepsin D is somewhat at variance with that of the two other hydrolases. (iii) Plasma membrane is tentatively detected by alkaline phosphodiesterase I. Largely recovered in the P fraction, this enzyme equilibrates at a median density close to that of the lysosomal hydrolases; the bulk of cholesterol and about half of the leucyl-2-naphthylamidase are closely associated with alkaline phosphodiesterase I; HTC cells do not contain typical 5'-nucleotidase. (iv) Catalase-bearing particles, of high buoyant density (1.22 g/cm3) are present, but 30-40% of the catalase is also found readily soluble. NADPH- and NADH: cytochrome c reductase, and RNA show more complex distributions. It is suggested that the former enzyme is associated with the endoplasmic reticulum; as in liver, NADH reductase activity is shared between the endoplasmic reticulum and the mitochondria; half of the RNA is associated with free ribosomes of polysomes. True glucose-6-phosphatase could not be detected.
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PMID:Analytical fractionation of cultured hepatoma cells (HTC cells). 56 43

The influence of sodium nitroprusside (SNP) on mitochondrial respiration was examined in rat liver mitochondria. The addition of SNP 1 mmol litre-1 during state 3 respiration inhibited the oxygen uptake by 63.4%. A mixture of SNP 1 mmol litre-1 and glutathione (GSH) 1 mmol litre-1 inhibited the oxygen uptake more markedly (by 75.9%). The cyanide concentrations were 0.01 mmol litre-1 with SNP alone and 0.15 mmol litre-1 with the mixture of SNP and GSH. Cyanide production from SNP in the presence of various reducing agents was studied in potassium phosphate 0.1 mol litre-1 buffer solution (pH 7.4) incubated at 37 degrees C. Cyanide was liberated markedly from SNP in the presence of GSH or ascorbate. Less cyanide was produced in the presence of NADH or NADPH. The rate of production of cyanide was dependent entirely upon the concentration of each reducing agent added. No cyanide was liberated when sodium dithionite or the oxidized forms of GSH, NAD or NADP were used. It was concluded that SNP is degradated to cyanide by a hydrogen donor and that the cyanide liberated in this manner inhibits the cytochrome oxidase activity of mitochondria in vivo.
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PMID:Inhibition of mitochondrial respiration by sodium nitroprusside and the mechanism of cyanide liberation. 58

The object of the study was the investigation of the occurrence and distribution of some oxidative enzymes in the sporocyst of Fasciola hepatica L. The samples were examined for the presence of cytochrome oxidase, peroxidase, NADH and NADPH tetrazolium reductases, as well as succinate, isocitrate, malate, lactate, alpha-glycerophosphate, glyceraldehyde-3-phosphate, glucose-6-phosphate, beta-hydroxybutyrate, L-glutamate and alcohol dehydrogenases. All of them save cytochrome oxidase were found to occur in the sporocyst. The presence and localization of these enzymes were examined by histochemical methods in various stages of development of the sporocyst. These investigations permitted it to be established that glycolytic processes are the principal way of release of energy for all developmental groups of this larva. Moreover, the functions of the tricarboxyl acid and pentose-phosphate cycles were detected and found to play a less important part in processes of energy production in the sporocyst. In addition, the functioning and metabolism of each larval organ in various stages of its development were discussed in so far as was possible on the basis of the analysis of the above-mentioned oxidative enzymes.
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PMID:Oxidative enzymes in the development of Fasciola hepatica L. III. The activities of oxidases and dehydrogenases in the sporocyst. 119 74

Energization of the pyridine nucleotide transhydrogenase in everted membrane vesicles from Escherichia coli JM83 was compared with the process in vesicles of the same strain transformed with the plasmid pDC21 overexpressing this enzyme. Proton translocation was assayed by the quenching of the fluorescence of the probe quinacrine. Agents able to discharge transmembrane proton gradients such as nigericin and the uncouplers 3,3',4',5-tetrachlorosalicylanilide and carbonyl cyanide m-chlorophenylhydrazone inhibited ATP-dependent transhydrogenation of NADP by NADH and discharged transmembrane proton gradients generated by transhydrogenation of AcNAD by NADPH, by oxidation of NADH, and by hydrolysis of ATP. This was observed in everted membrane vesicles of both strains JM83 and JM83pDC21. These strains differed significantly in the response of the NADH oxidation-dependent transhydrogenase. This reaction was inhibited by nigericin and uncouplers in membrane vesicles of JM83 but there was little inhibition or the reaction was stimulated in JM83pDC21, in spite of the discharge of the NADH oxidation-generated proton gradient measured by quinacrine fluorescence in the latter strain. It is proposed that the transhydrogenase is energized by direct or local (nonbulk phase) proton translocation in membranes of this strain. Uncouplers might facilitate these routes but would not discharge them. The generality of these observations was shown using other strains. NADH oxidase activity was severalfold lower in membrane vesicles of JM83pDC21 compared with JM83. The levels of ubiquinone and cytochromes, and the activities of NADH dehydrogenases I and II, and of cytochrome oxidase, were similar in the two strains. It is concluded that the NADH oxidase activity of JM83pDC21 is low because of the reduced rate of collision between electron-transferring complexes of the respiratory chain due to the large amount of transhydrogenase protein in the membranes of this strain. The large amount of transhydrogenase favors direct, nonbulk phase proton transfer. Transhydrogenase activity was stimulated by Ca2+, Mg2+, or Mn2+.
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PMID:Anomalous effect of uncouplers on respiratory chain-linked transhydrogenation in Escherichia coli membranes: evidence for a localized proton pathway? 131 Nov 61

In vitro alterations induced by a 10 micrograms/ml and 50 micrograms/ml dose each of thiophenate and fenbendazole on the absorptive surfaces of Haemonchus contortus (Nematoda: Trichostrongylidae) were studied. The most significant changes were induced in the gut epithelium. Alkaline phosphatase and adenosine triphosphatase activities were decreased, succinic dehydrogenase activity was increased, while acid phosphatase and glucose-6-phosphatase were completely lost from the intestinal epithelium after treatment with either of the drugs. A stimulatory effect of these two anthelmintics was observe on lactic dehydrogenase and reduced nicotinamide adenine dinucleotide diaphorase distribution. Thiophenate caused an increase in the activities of glutamate dehydrogenase (GDH), glucose-6-phosphate dehydrogenase (G-6-PD) and nonspecific esterases and a decrease in reduced nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-D) activity. Fenbendazole treatment led to the inhibition of GDH, while G-6-PD, NADPH-D, cytochrome oxidase, monoamine oxidase and nonspecific esterase activity remained unaltered in the epithelium.
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PMID:Histoenzymic effects of thiophenate and fenbendazole on the absorptive surfaces of Haemonchus contortus. 133 82

Human spermatozoa contain appreciable amounts of intracellular glutathione, which has a protective function against peroxidative degradation of spermatozoal polyunsaturated fatty acids by the NADPH-dependent glutathione peroxidase/reductase enzymatic system. The glutathione system provides a basic defense against peroxidative damage, without which the superoxide dismutase system would dominate. Since oxidative damage is said to include enzyme leakage and changes in metabolism, cytochrome oxidase and lactate dehydrogenase activities were used as indicators of the energy metabolism in unwashed and washed human spermatozoa during lipid peroxidation. Lipid peroxidation was induced by aerobic incubation of sperms in the presence of sodium ascorbate and ferrous sulphate. In addition, since NADPH concentrations influence the concentration of reduced glutathione, we studied glucose-6-phosphate dehydrogenase activity as an indicator of pentose phosphate shunt activity, the main source of NADPH. Microdensitometric measurements of the three enzymes were made by a Vickers M85a scanning microdensitometer. We found that the lipid peroxidation process greatly affects the 3 enzymatic activities examined and that seminal plasma protects against the extensive deleterious effects of lipid peroxidation.
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PMID:Cytophotometric assay of cytochrome oxidase, lactate dehydrogenase and glucose-6-phosphate dehydrogenase activities in human peroxidized spermatozoa. 133 42

Plasma membranes were isolated and separated from thylakoid membranes by discontinuous sucrose density gradient centrifugation of crude membranes prepared by French pressure cell extrusion of lysozyme-treated Anacystis nidulans. Two distinct populations of chlorophyll-free plasma membrane vesicles were obtained exhibiting buoyant densities of 1.087 and 1.100 g/cm3 as opposed to a uniform density of 1.192 g/cm3 for thylakoid membranes. Plasma and thylakoid membranes were characteristically different also with respect to fatty acid and protein composition, cytochrome oxidase activity, and pigment content as analyzed by spectrophotometry, spectrofluorimetry, and high performance liquid chromatography. Apart from carotenoids, chlorophyll a was the only major photosynthetic pigment detected in thylakoid membranes while plasma membranes contained virtually no chlorophyll a but (besides large amounts of carotenoids) protochlorophyllide a and chlorophyllide a as revealed by solvent partition (between n-hexane and acetone or methanol), room and low temperature fluorescence emission and excitation spectra, and analytical separation and identification by high performance liquid chromatography and comparison with authentic standards. The protochlorophyllide in the plasma membrane could be transformed into chlorophyllide in the dark in vitro by incubating the membrane preparation with NADPH; NADP+ effected the reverse transition.
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PMID:Chlorophyll precursors in the plasma membrane of a cyanobacterium, Anacystis nidulans. Characterization of protochlorophyllide and chlorophyllide by spectrophotometry, spectrofluorimetry, solvent partition, and high performance liquid chromatography. 250 Dec 98

In synaptosomes from rat cerebral cortex, the potential catalytic activity of some enzymes related to energy metabolism--namely, phosphofructokinase and citrate synthase--is not affected by aging. In contrast, the maximum velocity (Vmax) of cytochrome oxidase and of pyruvate dehydrogenase decreases in aged rats. A marked increase is found in the Vmax of glucose 6-phosphate dehydrogenase in aged rats and could be related to the availability of NADPH for antiperoxidative processes. Pretreatments of experimental animals with certain drugs were done to investigate the plasticity of enzyme proteins during aging. Papaverine, which acts on macrocirculation, is ineffective, but delta-yohimbine acting on microcirculation and metabolism and almitrine acting on oxygen availability both could interfere with the potential activity of some enzymes. However, their influence differs with the age of the rats.
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PMID:Age-related modification of enzyme activities in synaptosomes isolated from rat cerebral cortex. 254 Mar 42

Spectral examinations of hemoglobin-free perfused rat livers with a high-sensitivity reflectance spectrophotometer have revealed an accumulation of catalase Compound II to an amount comparable to that of Compound I under the aerobic steady state. This finding is in contrast to a recent proposal that NADPH associated with catalase both prevents and reverses the accumulation of Compound II (Kirkman, H. N., Galiano, S., and Gaetani, G.F. (1987) J. Biol. Chem. 262, 660-666). Furthermore, spectral species with a broad peak extending from 550 to 600 nm were observed in a time range between the methanol-induced decays of Compound I and Compound II. When rats were treated with 3-amino-1,2,4-triazole, catalase Compound I was not detected but spectral species with peaks at 570, 556 and 530 nm were observed. These novel spectral profiles suggest contributions from "peroxy" and "ferryl" forms of cytochrome oxidase.
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PMID:Ubiquitous formation of catalase compound II in hemoglobin-free perfused rat liver and detection of novel spectral species. 276 32

Sarcolemmal vesicles prepared by a new procedure from bovine tracheal smooth muscle were found to have a Na-Ca exchange activity that is significantly higher than that reported for different preparations from other types of smooth muscle. The exchange process system co-purified with 5'-nucleotidase, a plasma membrane marker enzyme, and was significantly enriched (over 100-fold) compared to mitochondria (cytochrome-c oxidase) but only slightly enriched (4-fold) compared to sarcoplasmic reticulum (NADPH-cytochrome-c reductase). The Na+ dependence of Ca2+ transport was demonstrated through both uptake and efflux procedures. The uptake profile with respect to Ca2+ was monotonic with a linear vo VS. vo.S-1 plot. The resultant Km of Ca2+ from the airway sarcolemmal vesicles (20 microM) was similar in magnitude to the Km of cardiac sarcolemmal vesicles (30 microM). Tracheal vesicles demonstrated a Vmax of 0.3-0.5 nmol.mg-1.s-1 which is significantly higher than that reported in preparations from other smooth muscle types. Furthermore, two processes found to stimulate cardiac Na-Ca exchange, pretreatment with either a mixture of dithiothreitol and Fe2+ or with chymotrypsin, were ineffective on the tracheal smooth muscle. Thus, the Na-Ca exchanger identified in tracheal smooth muscle appears to be different from that observed in cardiac muscle, implying that regulation of this activity may also be different.
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PMID:Sodium-calcium exchange in sarcolemmal vesicles from tracheal smooth muscle. 282 16


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