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 energy metabolism of the English E-CMO strain of contagious equine metritis bacterium was studied in whole cells and cell extracts. This bacterium appears to have an active Krebs cycle and probably obtains energy by oxidative phosphorylation since glycolysis and the hexose monophosphate pathways appear to be absent. These conclusions are based on the findings that [U-14C]glucose incorporation by this bacterium is below the level of detection, and that respiration is stimulated by Krebs cycle intermediates (i.e., malate, citrate, and succinate), but not by glucose, fructose, maltose, or sucrose. Furthermore, support comes from the fact that enzymes generally associated with the Krebs cycle and electron transport (i.e., malate dehydrogenase, succinate dehydrogenase, isocitrate dehydrogenase, fumarate hydratase, malate dehydrogenase [decarboxylating], cytochrome oxidase, superoxide dismutase, NADH dehydrogenase, and catalase) were detected. Those enzymes normally associated with glycolysis and the hexose monophosphate pathways (i.e., hexokinase, glucose 6-phosphate dehydrogenase, fructose biphosphate aldolase, glycerol 3-phosphate dehydrogenase, phosphoenolpyruvate carboxykinase, pyruvate kinase, phosphate acetyl transferase, acetate kinase, alcohol dehydrogenase, and lactate dehydrogenase) were below the level of detection.
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PMID:Energy metabolism of the contagious equine metritis bacterium. 708 71

Differential screening of an adrenal cortex cDNA library for corticotropin (ACTH)-inducible genes led to the isolation of a group of cDNAs representing mitochondrial genes that encode subunits of cytochrome oxidase, ATPase, and NADH dehydrogenase. Northern blot analysis of RNA from cells stimulated by ACTH confirmed the induction of these genes by ACTH yet revealed major differences in the relative responses of the respective mRNAs. The levels of mRNAs for cytochrome oxidase subunit I and ATPase increased 2- to 4-fold and for NADH dehydrogenase subunit 3 increased 20-fold, whereas the levels of the mitochondrial 16S rRNA showed no change within 6 h of ACTH stimulation. These effects of ACTH on mitochondrial mRNA levels probably result from both activation of the H2 transcription unit that encodes mitochondrial mRNAs and alteration of mRNA stability. ACTH also increased the activity of cytochrome oxidase after 12 h of stimulation. Examination of the tissue specificity of expression of five mitochondrial genes showed a wide range of RNA levels among 11 tissues but high correlations between individual RNA levels, consistent with a coordinated expression of the mitochondrial genes, although at different levels in each cell type. Proportionately high levels of mitochondrial mRNAs were found in adrenal cortex, probably reflecting a stimulatory effect of ACTH in vivo. Overall, the results indicate that ACTH enhances the energy-producing capacity of adrenocortical cells.
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PMID:Mitochondrial-genome-encoded RNAs: differential regulation by corticotropin in bovine adrenocortical cells. 750 67

Screening subtraction libraries from normal and type II diabetic human skeletal muscle, we identified four different mitochondrially encoded genes which were increased in expression in diabetes. The genes were cytochrome oxidase I, cytochrome oxidase III, NADH dehydrogenase IV, and 12s rRNA, all of which are located on the heavy strand of the mitochondrial genome. There was a 1.5- to 2.2-fold increase in the expression of these mRNA molecules relative to total RNA in both type I and type II diabetes as assessed by Northern blot analyses. Since there was approximately 50% decrease in mitochondrial DNA copy number as estimated by Southern blot analyses, mitochondrial gene expression increased approximately 2.5-fold when expressed relative to mitochondrial DNA copy number. For cytochrome oxidase I similar changes in mitochondrial gene expression were observed in muscle of nonobese diabetic and ob/ob mice, models of type I and type II diabetes, respectively. By contrast there was no change or a slight decrease in expression of cytochrome oxidase 7a, a nuclear-encoded subunit of cytochrome oxidase, and the expression of mitochondrial transcription factor 1 in human skeletal muscle did not change with type I or type II diabetes. The increased mitochondrial gene expression may contribute to the increase in mitochondrial respiration observed in uncontrolled diabetes.
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PMID:Increased expression of mitochondrial-encoded genes in skeletal muscle of humans with diabetes mellitus. 753 91

The complete nucleotide sequence of the circular mitochondrial (mt) DNA from the red alga Chondrus crispus was determined (25,836 nucleotides, A+T content 72.1%). Fifty one genes were identified. They include genes encoding three subunits of the cytochrome oxidase (cox1 to 3), apocytochrome b (cob), seven subunits of the NADH dehydrogenase complex (nad1 to 6, nad4L), two ATPase subunits (atp6 and atp9), three ribosomal RNAs (rrn5, srn and lrn), 23 tRNAs and four ribosomal proteins (rps3, rps11, rps12 and rpl16). Two subunits of the succinate dehydrogenase complex (sdhB and sdhC), usually found on nuclear genomes, are also located on the mtDNA of C. crispus. One group IIb intron is inserted in the tRNAIle gene. Six potentially functional open reading frames were identified, four of them having counterparts among green plant mtDNAs. The use of a modified genetic code and the absence of RNA editing, previously reported for the cox3 gene, appears as a general characteristic of this molecule. Mitochondrial genes are encoded on both DNA strands, in two opposite major transcriptional directions, suggesting the existence of two main transcriptional units. Two long and stable stem-loops were identified in intergenic regions, which are believed to be involved with transcription and replication. The main structural features of this genome are compared with the overall organization of mtDNAs and are discussed in view of the evolution of mitochondria.
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PMID:Complete sequence of the mitochondrial DNA of the rhodophyte Chondrus crispus (Gigartinales). Gene content and genome organization. 761 69

Electron transport and production of O2-/H2O2 by the NADH dehydrogenase flavin-semiquinone (FMNH.) and ubisemiquinone (UQH.) were studied in a model of in vivo ischemia-reperfusion in rat kidney. H2O2 production rates were assessed in isolated mitochondria using either succinate, with and without antimycin, or malate-glutamate, with and without rotenone. Respiratory activities of isolated mitochondria and activity of NADH- and succinate-cytochrome c reductase and of NADH- and succinate-dehydrogenase in submitochondrial particles were measured to evaluate the electron flux throughout respiratory carriers. The mitochondrial H2O2 production rate was approximately 1.5- and 4-times increased in ischemic and ischemic-reperfused kidneys, respectively. Ischemia caused a marked decrease in the electron transport throughout the NADH-UQ segment with no significant changes either in the NADH dehydrogenase activity or in the electron flux trough the succinate-cytochrome oxidase segment. Reperfusion did not further affect the NADH-ubiquinone segment but markedly inhibited the succinate-supported oxygen consumption, succinate-cytochrome c reductase and succinate dehydrogenase activity. Our results show a redistribution of the electron flux with an increased rate of superoxide anion/hydrogen peroxide production at NADH dehydrogenase in mitochondria subjected to ischemia only. After 10 min reperfusion an impairment of the electron flow at succinate-cytochrome c segment is established and hydrogen peroxide production by UQH. increases up to maximal values becoming the major source of superoxide anion/hydrogen peroxide.
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PMID:Mitochondrial sites of hydrogen peroxide production in reperfused rat kidney cortex. 772 10

The enzymes of mitochondrial respiratory chain, NADH dehydrogenase (complex I) and cytochrome c oxidase (complex IV), were completely inhibited by 6-hydroxydopamine with IC50 = 10.5 microM and IC50 = 34 microM respectively. The enzyme inhibition was insensitive to the change of NADH or cytochrome c concentrations. The extent of complex I inhibition decreased as a consequence of both non-enzymatic and monoamine oxidase-catalyzed oxidation of 6-hydroxydopamine. Monoamine oxidase A and B inhibitors, tranylcypromine and clorgyline but not l-deprenyl increased the extent of 6-hydroxydopamine induced inhibition of complex I. Thus, 6-hydroxydopamine itself and not its oxidation products may be responsible for the neurotoxicity of this agent via inhibition of respiratory chain enzymes.
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PMID:Inhibition of mitochondrial complexes I and IV by 6-hydroxydopamine. 779 73

The distribution of acetylcholinesterase (AChE), NADH dehydrogenase (NADHd), and cytochrome oxidase (CO) was determined in the nucleus of the solitary tract (NST) in the golden hamster. Histochemical staining was compared to cytoarchitectonic subdivisions of the NST (Whitehead: J. Comp. Neurol. 276:547-572, 1988) and to terminal fields of primary afferents of the nerves that innervate the tongue. These three histochemical methods resulted in differential staining patterns within the NST that were related to certain subdivisions. Transganglionic transport of horseradish peroxidase (HRP) was used to determine the central projections of the chorda tympani (CT), the lingual branch of the trigeminal (L-V), and the lingual-tonsilar branch of the glossopharyngeal nerves (L-IX). Alternate or the same brain sections were processed to reveal transported HRP, and NADHd or AChE levels. Increased staining of the neuropil with NADHd and AChE was coincident with the dense part of the afferent terminal fields of all three nerves in the NST and the laterally adjacent dorsomedial part of the spinal trigeminal nucleus. CO showed this pattern only for the most rostral part of the CT field. The densest AChE staining coincided with gustatory afferent terminal fields. The histochemical staining facilitated the interpretation of the organization of the NST. For example, at caudal levels of the gustatory NST, it is suggested that taste processing is localized predominantly in the medial part of the rostral central, and somatosensory processing in the rostral lateral subdivision. AChE or NADHd staining should facilitate studies of connections, topography, and neuroplastic changes of the gustatory NST.
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PMID:Organization of the nucleus of the solitary tract in the hamster: acetylcholinesterase, NADH dehydrogenase, and cytochrome oxidase histochemistry. 824 61

The existence of an organo-specific (heart) external NADH dehydrogenase located on the outer face of the inner mitochondrial membrane has been recently proposed. We have studied the respiration on external NADH in rat and beef heart mitochondrial fractions: (i) by using different mitochondrial isolation procedures on the rat, we observed that the higher the criteria of quality toward classical substrate respiration of mitochondrial fractions, the lower the external NADH-linked respiration; (ii) by using an especially loosely fitting glass-Teflon homogenizer, we obtained rat heart mitochondrial fractions practically free from external NADH linked respiration and with the highest respiratory control ratio on glutamate plus malate respiration. In rat and beef heart mitochondrial fractions containing an external NADH respiration: (i) ethoxyformic anhydride used previously to distinguish internal and external NADH oxidation was shown not to be specific; (ii) external NADH-linked respiration (although associated to the normally functioning respiratory chain as was shown by the effects of classic respiratory inhibitors) did not lead to ADP phosphorylation while glutamate plus malate did; (iii) respiratory activity on glutamate plus malate and external NADH was totally additive and the oxidation corresponded to two separate cytochrome oxidase pools, indicating a total functional separation between the two respiratory systems; (iv) NAD+ addition stimulated states 3 and 4 glutamate plus malate respiration to the same extent, indicating the presence of an appreciable number of internal dehydrogenases accessible to external cofactors. These results show that external NADH-linked dehydrogenase activity, which is usually detectable in mammal heart mitochondrial fractions, is of artefactual origin.
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PMID:The organo-specific external NADH dehydrogenase of mammal heart mitochondria has an artefactual origin. 839 14

Effect of the polycation on oxidative phosphorylation in the rat liver mitochondria has been studied. Both oxygen uptake and coupled phosphorylation were progressively inhibited by increasing concentration of the polycation, as observed with NAD-linked substrates, succinate and ascorbate+TMPD which activates the terminal part of the respiratory chain. NADH oxidase, NADH dehydrogenase and cytochrome oxidase were strongly inhibited by the polycation, 80-90% of the activity being lost at an inhibitor concentration of 100 microM. Succinate oxidase and succinate dehydrogenase were inhibited 60-66% at 100 microM concentration of the polycation. The polycation inhibited the uncoupler 2,4-dinitrophenol stimulated ATPase activity both in presence and absence of Mg2+ ions. The polycation also inhibited salt-induced volume change.
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PMID:Inhibition of mitochondrial oxidative phosphorylation and its electron transport pathway by a polycation in vitro. 850 25

The drug-resistant leukemic cell lines, CEM/VLB100 and K/DAU600, are more sensitive to tumor necrosis factor alpha (TNFalpha)-mediated cytotoxicity compared with their parental cell lines, CCRF-CEM and K562 cl.6. Drug-resistant leukemic cell lines have more active mitochondrial function, which is associated with a greater susceptibility to TNFalpha-induced respiratory inhibition. TNFalpha blocked electron transfer at three sites, NADH dehydrogenase (complex I), succinate dehydrogenase (complex II), and cytochrome c oxidase (complex IV). Respiratory rate and electron transport chain enzyme activities were significantly inhibited in the drug-resistant, TNF-sensitive cell lines. Respiratory inhibition preceded cell death by at least 5 to 8 hours. The respiratory failure was not compensated for by appropriate up-regulation of the glycolytic pathway. Increasing mitochondrial respiratory rate and enzyme activities by long-term culture with 2 mmol/L adenosine 5'-diphosphate (ADP) and Pi sensitized both drug-sensitive and drug-resistant cells to TNFalpha-induced cytolysis. Intramitochondrial free radicals generated by paraquat only had a limited and delayed effect on respiratory inhibition and cytolysis in comparison with the effect of TNFalpha. We conclude that TNFalpha-induced cytotoxicity in leukemic cells is, at least in part, mediated by inhibition of mitochondrial respiration. Free radical generation by TNFalpha may not directly lead to the observed inhibition of the mitochondrial electron transport and other mechanisms must be involved.
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PMID:Increased activity and sensitivity of mitochondrial respiratory enzymes to tumor necrosis factor alpha-mediated inhibition is associated with increased cytotoxicity in drug-resistant leukemic cell lines. 863 Apr 4


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