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)

NADH-diaphorase, succinate dehydrogenase (SDH), beta-hydroxybutyrate dehydrogenase (beta-HBDH), malate dehydrogenase (MDH) and cytochrome oxidase (CytO) were demonstrated histochemically in isolated perfused rat hearts during global ischaemia from 0 to 12 hours. The corresponding enzyme activities were measured when possible. The histochemically demonstrable activities of NADH-diaphorase and MDH decreased during the first hour of ischaemia. The time course of inactivation of biochemically detectable NADH-ferricyanide oxidoreductase was much the same as that of NADH-diaphorase. Both histochemically and biochemically detectable beta-HBDH gradually decreased by about 6 h of ischaemia. NADH-diaphorase but not MDH itself proved to be the rate-limiting factor when demonstrating MDH histochemically with nitroblue tetrazolium (NBT), whereas in the case of beta-HBDH the situation was probably the reverse. CytO and SDH activities did not change during the experimental period. Histochemistry clearly demonstrated ischaemic cellular injury, even though no significant diagnostic changes of ischaemia were visible by light microscopy. Even though this shows that enzyme-histochemical methods can be sensitive indicators of early ischaemic injury, in practice the time between the onset of injury and death as well as between death and autopsy must be taken into consideration when interpreting the results.
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PMID:Correlations between enzyme histochemical reactions and respective enzyme activities in global ischaemic rat hearts. 300 15

We compared the kinetics of cytochrome-c oxidase (cytochrome-c:oxygen oxidoreductase, EC 1.9.3.1) in fibroblasts derived from normal and cystic fibrosis individuals. The Km of the enzyme for reduced cytochrome c was significantly increased in CF cells; the change, however, was observed only at temperatures above 25 degrees C. The Vmax values were comparable in both types of individuals.
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PMID:Kinetic alterations of cytochrome-c oxidase in cystic fibrosis. 300 16

The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium ion (MPP+) on activities of enzyme complexes in the electron transport system were studied using isolated mitochondrial preparations from C57BL/6J mouse brains. Both MPTP and MPP+ dose-dependently inhibited activity of NADH-ubiquinone oxidoreductase (EC 1.6.5.3). The inhibition was reversible. Preincubation of freeze-thawed mitochondria with MPTP or MPP+ had no effect on the inhibition; however, when nonfrozen mitochondria were used, NADH-ubiquinone oxidoreductase activity was reduced to 46% of that in the nonincubated sample after a 5-min preincubation with MPTP and to 77% of that in the nonincubated sample after a 5-min preincubation with MPP+. Kinetic analyses revealed that inhibition of MPTP was noncompetitive and that of MPP+ uncompetitive with respect to NADH. On the other hand, inhibition of MPTP was uncompetitive and that of MPP+ noncompetitive with respect to ubiquinone. Succinate-ubiquinone oxidoreductase (complex II), dihydroubiquinone-cytochrome c oxidoreductase (complex III), and ferrocytochrome c-oxygen oxidoreductase (EC 1.9.3.1) activities were either slightly inhibited or not inhibited by MPTP or MPP+. The significance of these findings is discussed in relation to the mechanism of MPTP-induced neuronal degeneration.
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PMID:Effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenylpyridinium ion on activities of the enzymes in the electron transport system in mouse brain. 310 73

A temperature-sensitive respiration-deficient mutant of yeast lacks hemoproteins and accumulates coproporphyrin III when cultivated at elevated temperatures. Cells grown at 20 C respired normally and contained cytochromes a, b, and c. Cells grown at 35 C showed respiration-deficient mutant characters; they did not respire, lacked cytochromes, and accumulated coproporphyrin III. Addition of protoporphyrin IX or protohemin IX to the culture medium restored the respiratory activity of this mutant during growth at 35 C. The activities of various enzymes, including succinate-2,6-dichlorophenol indophenol (DCPIP), reduced nicotinamide adenine dinucleotide (NADH(2))-DCPIP, succinate-cytochrome c, and NADH(2)-cytochrome c oxidoreductase, and cytochrome oxidase, and the cytochrome c content of cells cultured in various conditions were determined. Changes in the number and structure of mitochondria were associated with changes in respiratory activity.
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PMID:Phenotype of a temperature-sensitive, respiration-deficient (cyt) mutant of yeast. 433 81

A number of methods were used to prepare a species of mammalian cytochrome oxidase (EC 1.9.3.1, ferrocytochrome c-oxygen oxidoreductase) in which only cytochrome a(3) is reduced and in combination with CO. The kinetics of CO binding by cytochrome a(3) (2+) in this species is significantly different from that exhibited by cytochrome a(3) (2+) in the fully reduced enzyme. The second-order rate constant for combination was 5x10(4)m(-1).s(-1) and the ;off' constant was 3x10(-2)s(-1). The kinetic difference spectra cytochrome a(3) (2+)-cytochrome a(3) (2+)-CO reveal further differences between the mixed-valence and the fully reduced enzyme. The reaction between cytochrome a(3) (2+) and oxygen in the mixed-valence species was followed in flow-flash experiments and reveals a fast, oxygen-dependent (8x10(7)m(-1).s(-1) at low oxygen) rate followed by a slow process, whose rate is independent of oxygen but whose amplitude is dependent on [O(2)]. The fast oxygen-dependent reaction yields as the first product the so-called ;oxygenated' enzyme. We conclude from these experiments that the ligand-binding behaviour of cytochrome a(3) depends on the redox state of its partners, a fact which represents clear evidence for site-site interaction in this enzyme. The fact that oxygen reacts rapidly with this enzyme species in which only one component, namely cytochrome a(3), is reduced represents clear and unequivocal evidence that this is indeed the O(2)-binding site in cytochrome oxidase and may indicate that reduction of oxygen can proceed via single electron steps.
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PMID:Studies on partially reduced mammalian cytochrome oxidase. Reactions with carbon monoxide and oxygen. 436 9

Cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1) was purified from the cytoplasmic membrane of the bacterium Paracoccus denitrificans. The enzyme contains two heme groups (a and a3) and two copper atoms per minimal unit, oxidizes mammalian cytochrome c at a high rate, and, when incorporated into liposomes, generates an electrochemical proton gradient during cytochrome c oxidation. Sodium dodecyl sulfate/polyacrylamide gel electrophoresis reveals only two subunits of apparent molecular weights 45,000 and 28,000; they appear to correspond to the two largest mitochondrially made subunits of the seven-subunit cytochrome c oxidase isolated from yeast mitochondria. Because of its structural simplicity. Paracoccus cytochrome c oxidase offers new possibilities for exploring the mechanism of cytochrome c oxidase function.
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PMID:A two-subunit cytochrome c oxidase (cytochrome aa3) from Paracoccus dentrificans. 624 43

Cytochrome c oxidase (ferrocytochrome c oxygen oxidoreductase, EC 1.9.3.1) was purified from beef heart mitochondria by affinity chromatography. Phospholipids were removed by washing the oxidase with detergent on the affinity column; 1 mole of cardiolipin remained per mole of heme a. The oxidase was mixed with excess cytochrome c in 1.5% (wt/vol) cholate to form a complex. Slow removal of the detergent from the mixture by dialysis resulted in crystallization of cytochrome oxidase in the form of a 1:1 complex with cytochrome c. The chemical composition and spectrophotometric properties of the crystal are described. Increasing the solubility of a hydrophobic membrane protein by combination with hydropholic ligand is demonstrated as a maneuver for crystallizing the membrane protein.
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PMID:Crystallization of part of the mitochondrial electron transfer chain: cytochrome c oxidase--cytochrome c complex. 624 93

Complex III (cytochrome bc1 particle; ubiquinol:ferricytochrome c oxidoreductase, EC 1.10.22) was purified from beef heart mitochondria by affinity chromatography. Phospholipids were depleted by washing the particle with detergent while it still was on the affinity column. The particle first was mixed with an excess of cytochrome c in 1.5% cholate (wt/vol); slow removal of the detergent from the mixture was achieved by dialysis. Freezing of the mixture resulted in crystallization of the cytochrome bc1 particle in the form of a 1:2 complex with cytochrome c. The chemical composition and spectrophotometric properties of the crystal are described. The same crystallization maneuver used in the case of cytochrome oxidase has been demonstrated to be effective in crystallizing the middle part of the mitochondrial electron-transfer chain.
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PMID:Crystallization of the middle part of the mitochondrial electron transfer chain: cytochrome bc1-cytochrome c complex. 625 56

Rat liver cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase; EC 1.9.3.1) was separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis into 12 different polypeptide chains. Specific antisera against the holoenzyme and against purified subunits IV and VIII were used to characterize the enzyme complex. The antiserum against subunit IV precipitates from sodium dodecyl sulfate-dissociated mitochondria only subunit IV and from Triton X-100-dissolved mitochondria all 12 polypeptide chains, indicating their integral location within the enzyme complex. Different antisera against the holoenzyme only precipitate subunits IV, V and VIb from sodium dodecyl sulfate-dissociated mitochondria, suggesting the location of these subunits on the surface layer of the complex. Subunit VIII is thought to be located within the complex, since a specific antiserum does not precipitate the complex. The amino acid composition of all 12 protein subunits is different, thus excluding their origin from proteolytic degradation. The proteolytic degradation of subunit IV into IV during isolation of the enzyme was corroborated by the very similar amino acid composition of both proteins.
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PMID:Immunological and chemical characterization of rat liver cytochrome c oxidase. 626 49

The catalytic properties of pulsed and resting cytochrome c oxidase (ferrocytochrome c: oxygen oxidoreductase, EC 1.9.3.1), expressed in terms of a minimal kinetic scheme and simulated by numerical computations, were successfully described. A two-state model, in which the relative amounts of the enzyme present in each conformation are regulated by the rates of electron flux and O2 binding on one side and the interconversion rates on the other, accounts for the activation of cytochrome c oxidase during turnover.
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PMID:A plausible two-state model for cytochrome c oxidase. 627 12


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