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)

1. Beef heart mitochondria have a cytochrome c1:c:aa3 ratio of 0.65:1.0:1.0 as isolated; Keilin-Hartree submitochondrial particles ahve a ratio of 0.65:0.4:1.0. More than 50% of the submitochondrial particle membrane is in the 'inverted' configuration, shielding the catalytically active cytochrome c. The 'endogenous' cytochrome c of particles turns over at a maximal rate between 450 and 550 s-1 during the oxidation of succinate or ascorbate plus TMPD; the maximal turnover rate for cytochrome c in mitochondria is 300-400 s-1, at 28 degrees-30 degrees C, pH 7.4. 2. Ascorbate plus N,N,N',N'-tetramethyl-p-phenylene diamine added to antimycin-treated particles induces anomalous absorption increases between 555 and 565 nm during the aerobic steady state, which disappear upon anaerobiosis; succinate addition abolishes this cycle and permits the partial resolution of cytochrome c1 and cytochrome c steady states at 552.5-547 nm and 550-556.5 nm, respectively. 3. Cytochrome c1 is rather more reduced than cytochrome c during the oxidation of succinate and of ascorbate + N,N,N',N'-tetramethyl-p-phenylene diamine in both mitochondria and submitochondrial particles; a near equilibrium condition exists between cytochromes c1 and c in the aerobic steady state, with a rate constant for the c1 leads to c reduction step greater than 10(3) s-1. 4. The greater apparent response of the c/aa3 electron transfer step to salts, the hyperbolic inhibition of succinate oxidation by azide and cyanide, and the kinetic behaviour of the succinate-cytochrome c reductase system, are all explicable in terms of a near-equilibrium condition prevailing at the c1/c step. Endogenous cytochrome c of mitochondria and submitochondrial particles is apparently largely bound to cytochrome aa3 units in situ. Cytochrome c1 can either reduce the cytochrome c-cytochrome aa3 complex directly, or requires only a small extra amount of cytochrome c to carry the full electron transfer flux.
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PMID:Catalytic activity of cytochromes c and c1 in mitochondria and submitochondrial particles. 17 75

Fluorocitrate, an inhibitor of the tricarboxylic acid cycle at the aconitase reaction, produces a time and dose related neural dystrophy in the guinea pig cochlea. There is direct inhibition of succinic dehydrogenase activity but not nicotinamide adenine dinucleotide dehydrogenase and cytochrome oxidase via cytochrome c activities. The dystrophic neural changes morphologically are similar to those noted in primary neural degeneration and neural presbycusis in man. Neural degeneration in aging appears to be the result of a dissociation of biochemical reactions preventing the proper utilization of organic fuel molecules for generation of energy and direct or indirect inhibition of respiration.
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PMID:Fluorocitrate ototoxicity. A morphologic and cytochemical model for primary neural degeneration in the guinea pig cochlea. 17 65

The ratio between the nitrite reductase and cytochrome oxidase activities of Pseudomonas aeruginosa nitrite reductase [EC 1.9.3.2.] varies with kind of C-type cytochrome used as the electron donor. Withe cytochrome c-548, 554 (Micrococcus sp.), the nitrite reductase activity is greater than the cytochrome oxidase activity, while the former is smaller than the latter with cytochrome c-554 (Navicula pelliculosa). The aerobic oxidation catalyzed by this enzyme of denitrifying bacterial ferrocytochrome c is greatly accelerated on addition of nitrite, while that of the algal ferrocytochrome c is not affected or is even depressed by the salt. An accelerative effect of nitrite is generally observed with many kinds of C-type cytochromes which react with the enzyme very or fairly rapidly. The difference in the ratio of the two activities of the enzyme seems to arise according to whether or not nitrite affects the interaction of C-type cytochrome with the enzyme.
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PMID:Change in the ratio of cytochrome oxidase activity to nitrite reductase activity of Pseudomonas aeruginosa nitrite reductase with the kind of C-type cytochrome used as an electron donor. 17 46

Rat heart and liver cytochrome concentrations were determined after three hypoxic conditions (atmospheric pressure 50.5 kPa, 40.8 kPa and 38.0 kPa) lasting one week and two weeks. The heart showed clear hypertrophy which was 38% in most severe hypoxia (38 kPa, 2 weeks). A small decline in the liver weight to body weight ratio was observed, this decrease being 21% in the most severe case. During the hypoxic periods the mitochondrial cytochrome concentration decreased. This phenomenon was more obvious when the degree of hypoxia was increased and more pronounced after 2 weeks than one week. The heart and liver showed quite similar patterns in this respect. In most severe hypoxia the decreases in the liver were 29% for cytochrome aa3, 30% for cytochrome b, 20% for cytochrome c and 15% for cytochrome c1, with the concentrations expressed on mitochondrial protein basis. The corresponding values in the heart were 31%, 43%, 28%, and 22%. It can be concluded that in mammals the mitochondrial cytochrome content probably varies according to the amount of oxygen available.
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PMID:Mitochondrial cytochrome concentrations in rat heart and liver as a consequence of different hypoxic periods. 17 79

Activities of succinate dehydrogenase, succinate- and NAD-H-cytochrome c--reductases, and cytochrome c--oxidase was compared in 1 g tissue homogenate and homogenate fractions made from 1 g brain tissue using various solutions. Fractionation resulted in the increased activities of NADH- and succinate cytochrome reductases, and in the loss of succinate dehydrogenase activity, cytochrome oxidase was less influenced. These phenomena are regarded as signs of the interrelation between mitochondria and other constituents of brain cell within homogenates. Maximal quantity of mitochondria isolated from homogenates is no more than 20% of all the mitochondrial homogenates (according enzyme data). The electronogram of the brain mitochondrial preparation isolated in the Krebs--Ringer solution without glucose pointed out to a high homogeneity of mitochondria in the residue.
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PMID:[Enzyme, electron microscopic and polarographic characteristics of isolated rat brain mitochondria. III. Quantitative assessment of their distribution in fractions of the homogenate]. 18 80

Studies were performed in the activities of certain enzymes from oxidoreductase group: cytochrome c-oxidoreductase (EC 1.6.99.3), succinate dehydrogenase succinates: cytochrome c-oxidoreductase (EC 1.3.99.1), cytochrome oxidase (EC 1.9.3.1) and malate dehydrogenase (EC 1.1.1.37) in mitochondria from neuronal and glial-enriched fractions. The mitochondrial fraction purity was observed by the electron microscope. The enzyme activity of the glial mitochondrial fraction was much higher than that in the neuronal mitochondria. Malate dehydrogenase from glial enriched fraction consists of three isoenzymes, while neuronal mitochondria had two isoenzymes of malate dehydrogenase. The neuronal mitochondria were found to be more stable to lubrol and digitonin.
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PMID:[Differences in the enzymatic activity of mitochondria from enriched neuronal and glial fractions]. 18 84

Horse heart cytochrome c was covalently bound to Sepharose 4B and its redox properties were measured under various experimental conditions. The equilibrium constant for the electron exchange between the oxidized and the reduced form of cytochrome c when one of the two forms was in the semi-solid state and the other one in solution was close to 1. Matrix-bound ferrocytochrome c is very stable to autoxidation and is not oxidized by O2 even in the presence of mammalian cytochrome oxidase. Oxidation occurs if catalytic amounts of soluble cytochrome c are added to the reaction mixture. The rate of oxidation of matrix-bound ferrocytochrome c in the presence of cytochrome oxidase and catalytic amounts of soluble cytochrome c may be correlated with the rate of electron transfer between soluble and matrix-bound cytochrome c. This rate is more than two orders of magnitude lower than that reported for the homonuclear (between identical species) electron transfer in solution.
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PMID:Electron transfer between soluble and immobilized mammalian cytochrome c. Equilibrium and kinetic studies on immobilized cytochrome c. 18 17

The reaction of cytochrome c with ethyl thioltrifluoroacetate was carried out under conditions which led to the selective trifluoroacetylation of a small number of the 19 lysines. The mixture of derivatives was separated by ion-exchange chromatography and four different derivatives with well-resolved 19F nuclear magnetic resonance (NMR) spectra were obtained. Peptide mapping techniques indicated that one of these derivatives contained a single trifluoroacetyl group at lysine 22, and another derivative was singly labeled at lysine 25. The trifluoroacetylated lysine 22 derivative was fully active toward both succinate-cytochrome c reductase (EC 1.3.99.1) and cytochrome oxidase (EC 1.9.3.1) white the trifluoroacetylated lysine 25 derivative was fully active toward the reductase, but had a threefold greater Michaelis constant in the cytochrome oxidase reactin. This supports the hypothesis that the cytochrome oxidase binding site is located in the heme cervice region, and that Lys-25 is important in the binding. 19FNMR spectra of the cytochrome c derivatives bound to phospholipid vesicles were obtained. The reasonably narrow line widths (35-65 Hz) and good sensitivity of the trifluoroacetyl resonances indicated that they might be useful probes for the interaction of cytochrome c with intact mitochondria.
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PMID:An enzyme kinetics and 19F nuclear magnetic resonance study of selectively trifluoroacetylated cytochrome c derivatives. 18 7

Spectroelectrochemical studies are presented for the carbon monoxide complex of isolated, purified cytochrome c oxidase (EC 1.9.3.1) in solutions saturated with carbon monoxide. The results indicate a stoichiometry of three equivalents per oxidase-carbon monoxide complex molecule. Formal reduction potentials (Eo) of the two copper and one heme component at pH 7.0 were obtained by means of quantitative absorbance-charge titrations in the absence and presence of cytochrome c, and by means of a Nernstian "Minnaert" plot in the presence of cytochrome c. Analysis of the absorbance-charge curves from these titrations gave an indirect determination of the high potential, "invisible" copper component. The copper potentials in the carbon monoxide complex were found to be relatively unchanged with respect to those of the native enzyme. The Eo values obtained were: high potential ("invisible") copper (340 +/- 20 mV (NHE)), low potential copper (190 +/- 20 mV), and low potential heme (250 +/- 10 mV).
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PMID:Spectroelectrochemical investigations of stoichiometry and oxidation-reduction potentials of cytochrome c oxidase components in the presence of carbon monoxide: the "invisible" copper. 18 19

1. Cells of the hydrogen bacterium Alcaligenes eutrophus are broken by gentle lysis using lysozyme treatment in hypertonic sucrose followed by osmotic shock. By this method, 93% of the in vivo activity of the H2 oxidase is recovered and the ATPase remains particle bound. In contrast, cell disruption in a French pressure cell diminishes the in vivo activity of the H2 oxidase by 50% and solubilizes the bulk of the ATPase. 2. The bacterium contains a periplasmic cytochrome c with bands at 418, 521 and 550 nm (difference spectrum). In addition to cytochrome aa3, b-560, c-553 and o, low temperature difference spectra of membranes show the presence of two further cytochromes (shoulders at 551 and 553 nm). 3. The unsupplemented membrane fraction catalyses the oxidation of hydrogen, NADH, NADPH, succinate, formate and endogenous substrate (NAD linked) at rates 2--3-fold higher than membranes obtained from cells disrupted in a French pressure cell. With the exception of the H2 oxidase all oxidase activities in lysozyme membranes are sensitive to carbonylcyanide m-chlorophenylhydrazone (20-100% stimulation of oxygen uptake). 4. The cytoplasmic fraction contains a B-type cytochrome with absorption maxima at 436 and 560 nm, capable of combining with CO; it contains non-covalently bound protohaem. In alkaline solutions a spectral transition to the haemochrome type with bands at 423, 526 and 556 nm occurs. The addition of NADH to an aerobic suspension of this cytochrome elicits new absorption maxima at 418, 545 and 577 nm (difference spectrum), which are believed to represent an oxygenated form of the reduced cytochrome.
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PMID:Respiratory components and oxidase activities in Alcaligenes eutrophus. 18 46


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