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)

The goal of the present study was to isolate, for the first time, cytochrome oxidase subunit genes from murine brain complementary DNA library and to characterize the expression of these genes from mitochondrial and nuclear sources at both light and electron microscopic levels. Brain subunit III (mitochondrial) shared 100% identity with that of murine L cells. Subunit VIa (nuclear) was known to have tissue-specific isoforms in other species: the ubiquitous liver isoform and the heart/muscle isoform. Our brain subunit VIa shared 93% homology with that of the rat liver and 100% identity with the recently reported murine liver isoform, which is only 62% identical to that of the rat heart isoform. In situ hybridization with riboprobes revealed messenger RNA labelling that was similar, though not identical, to that of cytochrome oxidase histochemistry. Monocular enucleation in adult mice induced a significant down-regulation of both subunit messages in the contralateral lateral geniculate nucleus. However, the decrease in subunit III messenger RNAs surpassed that of subunit VIa at all time periods examined, suggesting that mitochondrial gene expression is more tightly regulated by neuronal activity than that of nuclear ones. At the electron microscopic level, subunit III messenger RNA was localized to the mitochondrial compartment in both cell bodies and processes, while that of nuclear-encoded subunit VIa was present exclusively in the extramitochondrial compartment of somata and not of dendrites or axons. Surprisingly, the message was primarily associated with the rough endoplasmic reticulum, suggesting a novel pathway for its synthesis and trafficking. Our results indicate that the unique properties of neurons impose special requirements for subunits of a single mitochondrial enzyme with dual genomic origins. At sites of high energy demands (such as postsynaptic dendrites and some axon terminals), mitochondrial-encoded cytochrome oxidase subunits can be locally transcribed and translated, and they provide the framework for the subsequent importation and incorporation of nuclear-encoded subunits, which are strictly synthesized in the cell bodies. Dynamic local energy needs are met when subunits from the two genomic sources are assembled to form functional holoenzymes.
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PMID:Brain cytochrome oxidase subunit complementary DNAs: isolation, subcloning, sequencing, light and electron microscopic in situ hybridization of transcripts, and regulation by neuronal activity. 902 65

We examined cell fixation with microwave irradiation (MWI) used in cytochemistry. MWI was applied to blocks of about 1 mm3 of mouse parotid glands at 500 W for about 5 sec in a fixative at 37 degrees C. The activities of endogenous peroxidase and mitochondrial cytochrome oxidase were demonstrated by using the DAB method with 3,3'-diaminobenzidine (DAB) and 0.01% H2O2. Under electron microscopy, peroxidase activity was localized in the nuclear envelope, endoplasmic reticulum and secretory granules. However, mitochondria cytochrome oxidase activity seemed to be rather weak against the MWI at 37 degrees C. Moreover, suspension of isolated hamster liver mitochondria was fixed by MWI and also demonstrated cytochrome oxidase activity by using the cytochemical methods with DAB, cytochrome c, catalase and sucrose. Such mitochondrial fractions were subjected to 6-second MWI given 10 or 18 times with an interval of 10 seconds with and without a chilled water bath. The final temperature of each fixative was kept at about 10 degrees C or rose to about 37 and 55 degrees C. When we took care to keep the temperature below 10 degrees C, the DAB reaction products accumulated in the mitochondrial intermembrane-intracristal space. No mitochondrial deposits were observed when the temperatures of the fixatives rose to 37 and 55 degrees C. These results indicated that peroxidase was very resistant to the heat with MWI fixation. Cytochrome oxidase is sensitive to the heat with MWI, so, a chilled water bath had to be used.
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PMID:Mitochondrial fixation for the detection of cytochrome oxidase activity using microwave irradiation. 958 12

Highly purified tonoplast and plasma membrane vesicles were isolated from microsomes of Arabidopsis thaliana by preparative free-flow electrophoresis. The most electronegative fractions were identified as tonoplast using nitrate-inhibited Mg2+-ATPase as enzyme marker. The least electronegative fractions were identified as plasma membrane using glucan-synthase II, UDPG: sterol-glucosyl-transferase, and vanadate-inhibited Mg2+-ATPase as enzyme markers. Other membrane markers, latent inosine-5'-diphosphatase (Golgi), NADPH-cytochrome-c reductase (endoplasmic reticulum) and cytochrome-c oxidase (mitochondria) were recovered in the fractions intermediate between tonoplast and plasma membrane. Immunoblot analysis of membrane fractions by antibodies directed against tonoplast and plasma membrane proteins confirmed the nature and the purity of the isolated membranes. The cytoskeletal protein actin, which was also identified by immunoblotting, was found to be specifically attached to the plasma membrane vesicles. The structural and functional integrity of the isolated membranes from Arabidopsis thaliana is discussed in the light of results obtained for the location of receptors and enzymes, or for the determination of ligand binding activity.
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PMID:Free-flow electrophoresis for fractionation of Arabidopsis thaliana membranes. 966 77

On the basis of our own experimental data and analysis of data from the literature the existence of nitric oxide cycle in mammals is substantiated. Two components underlie the nitric oxide cycle: 1) the reaction catalyzed by NO-synthases (constitutive, inducible, and endothelial--NOS-I, -II, and -III); and 2) the nitrite-reductase reactions catalyzed by electron-donor systems with the participation of NADH, NADPH, flavoproteins, and heme-containing proteins. In mammalian cells NO is enzymatically formed from terminal guanidine nitrogen of L-arginine by a family of at least three distinct NOS isoenzymes. As a result of nonenzymatic/enzymatic NO oxidation, NO2- and NO3- ions are formed: L-Arg --> NO --> NO2-/NO3-. The reduction of NO2- ions to NO occurs via the nitrite-reductasereaction: NO2- + e- --> NO. The reduction of NO2- ions to NO is realized by electron-donor systems with the participation of NADH, NADPH, flavoproteins, and cytochrome oxidase in mitochondria and by NADH, NADPH, flavoproteins, and cytochrome P-450 in endoplasmic reticulum. In erythrocytes the reduction of NO2- ions to NO is catalyzed by electron-donor systems with participation of NADH, NADPH, flavoproteins, and deoxy-hemoglobin. The role of ascorbic acid and reduced glutathione should be noted among low-molecular-weight compounds. Thus, the presence of the nitric oxide cycle provides the cyclic transformation as follows: L-arginine --> NO --> NO2-/NO3- --> NO.
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PMID:NO-synthase and nitrite-reductase components of nitric oxide cycle. 972 40

This study was designed to investigate the possible oxidative changes associated with alterations in cytochrome P450 levels in rat liver. Accordingly, extent of peroxidative processes, cytochrome and antioxidant content, capacity to face an oxidative stress were determined in liver microsomes, mitochondria, and homogenates from normal and phenobarbital (PB)-treated rats. Liver content of microsomal and mitochondrial proteins was also determined by the values of the activities of marker enzymes (glucose-6-phosphatase and cytochrome oxidase, respectively) in liver homogenate and in two cellular fractions. The increase in the liver content of microsomal and mitochondrial proteins indicated that PB caused proliferation of both smooth endoplasmic reticulum and mitochondrial population. Treatment with PB also gave rise to a general increase in peroxidative reactions (evaluated measuring malondialdehyde and hydroperoxides (HPs)), in the different cell compartments, even though HPs were not found significantly increased in mitochondrial fraction. The increase in peroxidative processes was associated with significant decreases in antioxidant concentration (expressed in terms of equivalent concentration of an antioxidant, such as the desferrioxamine), in all preparations from PB-treated rats. The response to oxidative stress in vitro (evaluated determining the parameters characterizing light emission from preparations stressed with sodium perborate) showed a substantial PB-induced increase in the susceptibility to oxidative challenge only in liver homogenate. The lack of changes in the mitochondrial preparations is likely due to decrease in concentration of both free radical producing species and antioxidants. The lack of changes in microsomal fraction is apparently in contrast with its lower oxidant capacity and higher content of cytochromes which are able to determine sensitivity to pro-oxidants. However, it could be due to the ability of cytochrome P450 to interact with the active oxygen species formed at its active center.
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PMID:Effect of phenobarbital treatment on characteristics determining susceptibility to oxidants of homogenates, mitochondria and microsomes from rat liver. 994 58

Endogenous excitotoxins that act on receptors of cerebral excitatory amino acids play important roles in the pathogenesis of excitotoxic brain diseases. Activation of excitatory amino acid receptors results in neuronal death characteristic of these disorders. Kynurenic acid, a powerful endogenous excitatory amino acid receptor antagonist, which is therefore widely regarded as a potent neuroprotective agent, is produced from its biological precursor, L-kynurenine, by the action of the enzyme kynurenine aminotransferase-I. The chemical hypoxia induced by mitochondrial toxins produces a secondary excitotoxicity, leading to the activation of N-methyl-D-aspartate receptors. Accordingly, sodium azide, an inhibitor of cytochrome oxidase, induces the release of excitotoxins via an energy impairment and this, in turn, results in neurodegeneration. Since energy-dependent secondary excitotoxic mechanisms also account for the pathogenesis of neurodegenerative diseases, a study was made of the effects of sodium azide on the immunohistochemical localization of kynurenine aminotransferase-I. After in vivo administration of sodium azide for five days, a markedly decreased glial kynurenine aminotransferase-I immunoreactivity was found by immunohistochemical techniques in the glial cells of the striatum, hippocampus, dentate gyrus and temporal cortex; at the same time, kynurenine aminotransferase-I started to be expressed by nerve cells which had not been immunoreactive previously. The accumulation of kynurenine aminotransferase-I reaction product around the ribosomes of neuronal endoplasmic reticulum suggests de novo synthesis of kynurenine aminotransferase-I in the reactive nerve cells.
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PMID:Effects of in vivo sodium azide administration on the immunohistochemical localization of kynurenine aminotransferase in the rat brain. 1061 17

The procedures recently developed in our laboratory to observe three-dimensional structures of cell organelles in thick biological specimens by means of high voltage electron microscopy are reviewed. Thick biological specimens such as whole mount cultured cells seeded and grown on grid meshes in culture vessels or thick sections cut from embedded tissues and stained by histochemical reactions can be readily observed three-dimensionally by high voltage transmission electron microscopy at 400-1000kV. Cultured cells used were both primary cultures from animal tissues and established cell lines maintained in our laboratory. The livers of adult Wistar rats were isolated by collagenase perfusion, and hepatocytes were suspended in a Leibovitz medium and seeded on formval coated gold grid meshes in Petri dishes, incubated in a CO(2) incubator in a humidified atmosphere containing 5% CO(2) in air at 37 degrees C for a few days. Established cell lines, CHO-K1 cells, were cultured in Ham's F12 medium, while HeLa cells were cultured in Eagle's MEM under the same condition. Some of the cells were cultured under experimental conditions such as hepatocyte culture in the medium containing peroxisome proliferating agents such as clofibrate or bezafibrate and some of them were labeled with (3)H-thymidine, (3)H-uridine, (3)H-labeled precursors and (14)C-bezafibrate. Also some cells were incubated in medium containing HRP to induce pinocytosis. All the whole mount cultured cells on grid meshes were prefixed in buffered 2.5% glutaraldehyde, stained with various histochemical reactions and postfixed in 1% osmium tetroxide. The histochemical reactions used were glucose-6-phosphatase (G-6-Pase), thiamine pyrophosphatase (TPPase), cytochrome oxidase, acid phosphatase (AcPase), DAB, ZIO, PA-TCH-SP reactions and radioautography was performed after labeling with radiolabeled compounds. The whole mount cultured cells were dried in a critical point dryer and were observed with JEOL JEM-4000EX or Hitachi H-1250M high voltage electron microscopes at 400-1000kV. By tilting the specimens' stereo-pair micrographs were recorded and they were observed with stereoscopes. Rat liver, mouse intestine and pancreas tissues, fixed and stained as above, were embedded in Epoxy resin, thick sectioned at 1-2 microm and were observed as for the whole mount cultured cells at 1000kV. Stereo-pairs were further analyzed with an image analyzer JEOL JIM-5000 (JEOL, Tokyo, Japan), producing two contour lines plotted from the micrographs at a thickness of 0.2 microm and were observed with anaglyph type glasses, demonstrating the depth or heights of respective cell organelles. The results show that whole mount cultured cells and thick sections stained with histochemical reactions reveal cell organelles corresponding to marker enzymes, such as G-6-Pase in endoplasmic reticulum, TPPase and ZIO in Golgi apparatus, cytochrome oxidase in mitochondria, AcPase in lysosomes, DAB in peroxisomes and pinocytotic vesicles, PA-TCH-SP in secretory granules, (3)H-thymidine and (3)H-uridine in nuclei, (3)H-animo acids in endoplasmic reticulum and secretory granules, (14)C-bezafibrate around ER and peroxisomes. The ultrastructure of these cell organelles as well as the structural relationship between them can be demonstrated three-dimensionally with stereo-pair images. Overall, these procedures are useful for analyzing stereologically the ultrastructure of cell organelles in cells and tissues.
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PMID:Three-dimensional high voltage electron microscopy of thick biological specimens. 1107 Mar 59

A strain derived from a colony of BALB/c mice at the National Center for Toxicological Research, Jefferson, AR, USA (NCTR-BALB/c) suffers from an autosomal recessive disorder characterized by proliferation of secondary lysosomes with accumulation ofunesterified cholesterol in several tissues. The unesterified cholesterol content of spleens and lungs from the affected mice were elevated 8- and 3-fold respectively over age- and sex-matched controls. Postnuclear supernatants of tissue homogenates were fractionated by sucrose density gradient centrifugation and the fractions were analyzed for unesterified cholesterol, protein and marker enzyme activities for lysosomes (N-acetyl-beta-D-glucosaminidase, beta-D-glucuronidase), plasma membrane (alkaline phosphodiesterase I), endoplasmic reticulum (glucose-6-phosphatase) and mitochondria (cytochrome oxidase). The enzyme distribution profile showed that lysosomes of affected tissues floated at low density regions (density 1.05-1.08) of the gradient and contained substantial amount of tissue unesterified cholesterol. These low density lysosomes were purified about 17-fold (58% yield) from spleen and about 6-fold (32% yield) from lungs with minimal contamination by other organelles They were mostly intact as judged by high latency for N-acetyl-beta-D-glucosaminidase activity (70-100%). Lysosomes of control tissues were not found at the low density regions. The distribution profiles for other organelles were similar between affected and control tissues. Phospholipid composition of low density lysosomes were distinctly different from their respective tissue homogenates. Spleen and lung lysosomes were enriched in sphingomyelin and phosphatidylcholine respectively. The results suggest that these lysosomes acquire their low densities due to accumulation of unesterified cholesterol, the retention of which may be aided by sphingomyelin and phosphatidylcholine content of the lysosomes.
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PMID:Lysosome lipid storage disorder in NCTR-BALB/c mice: spleen and lung lysosomes store unesterified cholesterol but differ in their phospholipid composition. 1119 85

Recently, we reported that in various cell lines under conditions of deenergization of the mitochondrial membrane, the release of Ca(2+) from the endoplasmic reticulum (ER) does not produce the expected activation of store-operated calcium channels (SOCs) in the plasma membrane. In the present work, we examined the activation of SOCs in fibroblasts derived from three patients with Leigh disease (LS). We identified mutations in the SURF-1 gene in all these cells. Consequently, cytochrome oxidase (COX) deficiency was found in all these (LS(COX)) cell lines and, thus, the main mitochondrial mechanism of generation of the electrochemical proton gradient on the mitochondrial membrane was naturally depressed. We demonstrated that, in untreated LS(COX) fibroblasts, the rate of Ca(2+)-inflow through SOCs was low compared to the fibroblasts from healthy individuals even after thapsigargin-induced maximal release of Ca(2+) from the ER. Moreover, the pretreatment of LS(COX) fibroblasts with a protonophore did not modify this rate. Thus, in LS(COX) fibroblasts, the activation of SOCs was naturally impaired. Our findings suggest that altered calcium metabolism, apart from severe energy production failure, may also contribute to developing pathological conditions in patients with COX-deficient Leigh disease related to SURF-1 gene mutation.
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PMID:Abnormal calcium homeostasis in fibroblasts from patients with Leigh disease. 1134 80

Submandibular glands of the hamster were irradiated in 2% paraformaldehyde (pFA)-0.5% pure glutaraldehyde (PGA) with a microwave (MW) processor at temperatures of 10 degrees and 37 degrees C. Electron microscopy showed that cytochrome oxidase activity was taking place in the mitochondrial intermembrane-intracristal space of the granular duct cell when the temperature of the MW-irradiated fixatives was at 10 degrees C. However, a decrease of this activity was observed when we took care to keep the temperature of the MW-irradiated fixatives at 37 degrees C. The distinct reduction of cytochrome oxidase activity allowed by MW irradiation seems to be due the thermal affects of fixatives. Of course, the possibility cannot be excluded that MW irradiation caused other undetectable membrane damage. Then, we used confocal laser scanning microscopy for the preservation check of the mitochondrial membrane for cytochemistry with MW-irradiated fixation. The fluorescence of rhodamine 123 was observed in the inner spaces of the mitochondria at temperatures of 10 degrees and 37 degrees C. When the same tissues were fixed with 2% pFA using an MW processor as the sole fixative at 10 degrees C, no mitochondrial fluorescence was observed. Cytochrome oxidase activity, by contrast, could be seen in the mitochondrial intermembrane-intracristal spaces in the same condition. Formaldehyde is not the best aldehyde for the purpose of ultrastructural preservation. On the other hand, light and electron microscopy showed that the endogenous peroxidase activity was localized in the nuclear envelope, endoplasmic reticulum, secretory granules, and Golgi apparatus of the hamster submandibular gland using 2% pFA-0.5% PGA fixative with and without MW irradiations at temperatures of 10 degrees and 37 degrees C. Some of the same cells were fixed with only 2% pFA under MW irradiation at 10 degrees C; however, marked diffuseness of the peroxidase activity was observed. Therefore, these results indicated that cytochrome oxidase activity was sensitive to heat with MW-irradiated fixation. Peroxidase activity was very resistant to heat with MW-irradiated fixation but not with pFA solo fixation, therefore, PGA had to be used.
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PMID:Cytochrome oxidase activity and confocal laser scanning microscopic analysis of the hamster submandibular gland using microwave irradiated fixation. 1250 86


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