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)

The scheme for the identification of Gram-negative nonfermenting microorganisms is proposed. The scheme comprises the most important key signs, such as the cytochrome oxidase reaction determined by the method of Gaby and Hadley, the oxidation/fermentation test, maltose oxidation and motility, as well as additional key signs, among them gelatinase activity, the oxidation of 10% lactose, nitratase activity with the liberation of free nitrogen, the utilization of the sources of carbon and energy (glucose and sodium acetate) in limited media containing ammonium salts and nitrates as the sources of nitrogen. Additional tests for the identification of nonfermenting microorganisms similar in their main key signs are also recommended.
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PMID:[Taxonomic identification of gram-negative nonfermenting microorganisms in environmental research]. 298 90

Addition of 1 eq of fluorescein mercuric acetate (FMA) to beef heart cytochrome oxidase was found to inhibit the steady-state electron transfer activity by 50%, but further additions up to 10 eq had no additional effect on activity. The partial inhibition caused by FMA is thus similar to that observed with other mercury compounds (Mann, A. J., and Auer, H. E. (1980) J. Biol. Chem. 255, 454-458). The fluorescence of FMA was quenched by a factor of 10 upon binding to cytochrome oxidase, consistent with the involvement of a sulfhydryl group. However, addition of mercuric chloride to FMA-cytochrome oxidase resulted in an increase in fluorescence, suggesting that FMA was displaced from the high affinity binding site. Cytochrome c binding to FMA-cytochrome oxidase resulted in a 10% decrease in the fluorescence, possibly caused by Forster energy transfer from FMA to the cytochrome c heme. The binding site for FMA in cytochrome oxidase was investigated by carrying out sodium dodecyl sulfate gel electrophoresis under progressively milder dissociation conditions. When FMA-cytochrome oxidase was dissociated with 3% sodium dodecyl sulfate and 6 M urea, FMA was predominantly bound to subunit II following electrophoresis. However, when the dissociation was carried out at 4 degrees C in the absence of urea with progressively smaller amounts of lithium dodecyl sulfate, the labeling of subunit II decreased and that of subunit I increased. These experiments demonstrate that mercury compounds bind to a high affinity site on cytochrome oxidase, possibly located in subunit I, but then migrate to subunit II under the normal sodium dodecyl sulfate gel electrophoresis conditions. A definitive assignment of the high affinity binding site in the native enzyme cannot be made, however, because it is possible that mercury compounds can migrate from one sulfhydryl to another under even the mildest electrophoresis conditions.
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PMID:Specific labeling and partial inactivation of cytochrome oxidase by fluorescein mercuric acetate. 299 36

Cytochrome c oxidase contains a copper ion electron-transfer site, CuA, which has previously been found to be unreactive with externally added reagents under conditions in which the protein remains structurally intact. We have studied the reaction of cytochrome oxidase with sodium p-(hydroxymercuri) benzoate (pHMB) and found that the reaction proceeds, under appropriate conditions, to give an excellent yield of a particular derivative of the CuA center that has electron paramagnetic resonance and near-infrared absorption spectroscopic properties which are distinctly different from those of the unmodified center. Spectroscopic and chemical characterization of the other metal ion sites of the enzyme reveals little or no effect of the pHMB modification on the structures of and reactions at those sites. Of particular interest is the observation that the modified enzyme still displays a substantial fraction of the native steady-state activity of electron transfer from ferrocytochrome c to O2. Although the modified copper center retains the ability to receive electrons from the powerful reductant Na2S2O4 and to transfer electrons to O2, it is not significantly reduced when the enzyme is treated with milder (higher potential) reductants such as NADH/phenazine methosulfate or the physiological substrate ferrocytochrome c. CuA exhibits many spectroscopic and chemical properties which make it highly atypical of cuproprotein active sites; the singular nature of this site has prompted speculation about the importance of the structural peculiarities of this metal ion center in the catalytic cycle of the enzyme. In this work, we demonstrate that the unusual features of this site are not prerequisites for competent catalysis of electron transfer and O2 reduction by the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Chemical modification of the CuA center in cytochrome c oxidase by sodium p-(hydroxymercuri)benzoate. 299 87

Anti-cyanide action by sodium thiosulfate (ST) was enhanced by prior administration of chlorpromazine (CPZ). However, CPZ (alone) provided no protection against cyanide lethality. To investigate the possibility that CPZ enhances thiocyanate formation in ST-pretreated mice, the effects of CPZ on rhodanese activity and the time course of plasma thiocyanate concentrations were investigated. CPZ did not alter hepatic rhodanese kinetics nor did it enhance plasma thiocyanate concentrations in ST-pretreated mice. The effect of CPZ and ST on the time course of cytochrome oxidase inhibition and recovery, in vivo, was also investigated. At 4 mg KCN/kg, maximal inhibition of brain (40%) and heart (60%) cytochrome oxidase occurred 10 to 20 min post-challenge in control and CPZ-pretreated mice, while no inhibition occurred in ST- and CPZ/ST-pretreated mice. Twenty milligrams KCN/kg caused 100% lethality in control and CPZ-pretreated mice and 6/25 and 4/20 deaths were observed in ST- and CPZ/ST-pretreated mice, respectively. No significant inhibition of brain, heart, and liver cytochrome oxidase activities was observed in surviving ST- and CPZ/ST-pretreated mice challenged with 20 mg KCN/kg. Control and CPZ-pretreated mice died within 5 min of KCN challenge and had almost the same degree of inhibition of brain (35 and 29%, respectively) and heart (60 and 55%, respectively) cytochrome oxidase as did similarly pretreated mice 5 min after challenge with a nonlethal cyanide dose (4 mg/kg). Our results suggest that CPZ does not enhance the formation of thiocyanate in ST-pretreated mice. In addition, the similar degree of cytochrome oxidase inhibition noted after both lethal and nonlethal KCN treatments raises questions as to the ultimate target in cyanide-induced lethality.
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PMID:Antagonism of cyanide poisoning by chlorpromazine and sodium thiosulfate. 299 48

HPLC of the beef heart cytochrome oxidase subunits on TSKgel-column has been studied. It was found that the resolution of the subunits depends on the sodium dodecyl sulphate and buffer concentration. Strong interaction of subunits Va, VIc and VIIb with hydrophobic polypeptide chains was observed.
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PMID:[Highly effective liquid chromatography of cytochrome oxidase polypeptides]. 300 93

Growth of the freshwater cyanobacterium Synechococcus 6311 under saline conditions stimulated respiration tenfold during the first 24 h, while growth and photosynthesis were inhibited. The elevated respiration rate was seen under both light and dark conditions, was uncoupler and cyanide sensitive, and did not decrease upon salt removal. Membrane preparations from salt-grown cells exhibited a tenfold increase in cytochrome oxidase activity, while electron transfer rates from NADPH to cytochrome c only increased threefold. Cytochrome oxidase activities were correlated with levels of EPR detectable Cu2+ in the salt and control membranes. Sodium-driven proton (antiproter) gradients in salt-grown cells were sensitive to cyanide but not dicyclohexylcarbodiimide, indicating the direct role of respiratory electron transport in maintaining low intracellular sodium levels.
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PMID:The role of respiration during adaptation of the freshwater cyanobacterium Synechococcus 6311 to salinity. 300 47

The activity of the cytochrome oxidase, which is located in the plasma and the nuclear and the food-vacuole-limiting membranes as well as in the mitochondria of the trophozoites of Plasmodium berghei, was inhibited completely by sodium artesunate, an antimalarial drug, in vitro at 1 mM and in vivo at 100 mg/kg iv. This enzyme appears to be a target for the antimalarial mechanism of action of artesunate and qinghaosu.
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PMID:Antimalarial agents, 2. Artesunate, an inhibitor of cytochrome oxidase activity in Plasmodium berghei. 300 19

Membranes were isolated from the cyanobacterium Anacystis nidulans by French press extrusion of lysozyme-treated cells. The membranes were solubilized with sodium dodecylsulfate and subjected to denaturing polyacrylamide gel electrophoresis. Separated polypeptides were transferred to nitrocellulose by Western blotting, and incubated with antibodies against aa3-type cytochrome oxidase of Paracoccus denitrificans; antibodies against subunits I and II, and against the holoenzyme, were used and gave pronounced complementary cross reaction with two of the Anacystis membrane polypeptides corresponding to molecular weights of approximately 55,000 and 32,000, respectively. From this we conclude that an aa3-type cytochrome oxidase is present in Anacystis nidulans as was previously suggested from spectral evidence (G.A.Peschek, Biochim.Biophys.Acta 635 (1981) 470-475), and that this enzyme is composed of at least two subunits with apparent homology to subunits I and II of the corresponding Paracoccus cytochrome oxidase.
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PMID:Immunological identification of aa3-type cytochrome oxidase in membrane preparations of the cyanobacterium Anacystis nidulans. 301 Sep 64

The response of an established line of non-transformed adult rat liver epithelial cells (ARL 15) to thyroid hormone (T3) (3,5,3'-triiodothyronine) was characterized. Exposure of confluent monolayers to 1.10(-8) M T3 for 3 days increased O2 consumption (QO2) between 14-58%, ouabain-sensitive Rb+ uptake 26%, (Na+ + K+)-ATPase activity 32%, alpha-glycerophosphate dehydrogenase activity 103% and cytochrome oxidase activity 208%. The ARL 15 cells, maintained in continuous culture, therefore, exhibit the hallmarks of an authentic physiological response to thyroid hormone.
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PMID:The response of an established line of rat liver cells to thyroid hormone. 301 38

The cytochemical technique for the demonstration of cytochrome oxidase has been used to locate the sites of chronically active neurons in the CNS. The current experiments were undertaken to validate the use of this technique for the identification of active neurons and ganglia in the myenteric plexus of the gut. The excitotoxin veratridine was used to cause repetitive firing of action potentials and to depolarize myenteric neurons over an 8-hour test period in vitro. The effects of veratridine were monitored electrophysiologically and correlated with the ability of the drug to affect the density of the cytochrome oxidase reaction product, as well as the proportion of reactive myenteric neurons. The action of veratridine on cytochrome oxidase activity was evaluated by means of video microdensitometry and computer-assisted morphometry. Effects of veratridine were considered to be specific if they were blocked by the inclusion of tetrodotoxin (TTX), which antagonizes the action of veratridine on voltage-dependent Na+ channels. Veratridine (1.0 microM) depolarized the membranes of myenteric type II neurons and greatly increased both the average density of the cytochrome oxidase reaction product in individual neuronal cell bodies and the proportion that were reactive. The concentration-effect relationship for veratridine was biphasic. As the concentration of veratridine was raised, neurons became sufficiently depolarized such that they ceased to fire action potentials. This absence of spiking was associated with a decline in the stimulation of cytochrome oxidase activity by veratridine. At still higher concentrations of veratridine the degree of neuronal depolarization continued to increase. This further depolarization was associated with a secondary increase in cytochrome oxidase activity. All effects of veratridine were blocked by TTX. It is concluded that the cytochemical demonstration of cytochrome oxidase reflects the recent metabolic history and thus the physiological activity of myenteric neurons. In control preparations, fixed without exposure to veratridine, considerable variation in cytochrome oxidase was observed between ganglia and between individual neurons within ganglia. This suggests that there are significant differences in the activity of individual ganglia and neurons of the myenteric plexus. These observations support the hypothesis that there is a functional heterogeneity that corresponds to an anatomical heterogeneity (previously demonstrated) of the myenteric plexus.
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PMID:Functional heterogeneity in the myenteric plexus: demonstration using cytochrome oxidase as a verified cytochemical probe of the activity of individual enteric neurons. 301 35


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