Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q16795 (ubiquinone)
 5,455 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of ubiquinones with different length of their chain (CoQ0, CoQ1, CoQ2, CoQ6, CoQ9) and their synthetic analogues (analogues of ubiquinone-1, hexahydroubiquinone-4, monophytylquinone, diphytylquinone, triphytylquinone) on the activity of ubiquinone dependent enzyme systems was studied in mitochondrial fractions from the yeast Candida guilliermondii. All of the ubiquinone homologues studied activated these systems. The synthetic analogues of ubiquinone nonspecifically inhibited the activity of NADH2-oxidase system. The inhibition was reversible when CoQ0 and CoQ1, but not CoQ6 and CoQ9, were added to the system. In the succinate-CoQ-reductase system, the inhibition caused by the analogues of ubiquinone was eliminated when all of the tested homologues were added to the system. In contrast to other analogues of ubiquinone, hexahydroubiquinone-4 was an inhibitor for the NADH2-oxidase system and an activator for the succinate-CoQ-reductase system, and eliminated the inhibiting action of other ubiquinone analogues in this system. Similar action of ubiquinone homologues was shown in the elimination of the inhibition of ubiquinone dependent systems caused by the specific inhibitors of electron transport, viz. rotenone and antimycin A.
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PMID:[Effect of ubiquinones and their analogs on the respiratory chain enzyme activity of Candida guilliermondii yeasts]. 53 Jan 41

We have investigated the role of the Coenzyme Q pool in glycerol-3-phosphate oxidation in hamster brown adipose tissue mitochondria. Antimycin A and myxothiazol inhibit glycerol-3-phosphate cytochrome c oxidoreductase in a sigmoidal fashion, indicating that CoQ behaves as a homogeneous pool between glycerol-3-phosphate dehydrogenase and complex III. The inhibition of ubiquinol cytochrome c reductase is linear at low concentrations of both inhibitors, indicating that sigmoidicity of antimycin A and myxothiazol inhibition is not a direct property of antimycin A and myxothiazol binding. Glycerol-3-phosphate cytochrome c oxidoreductase is strongly stimulated by added CoQ3, indicating that endogenous CoQ is not saturating. Application of the pool equation for nonsaturating ubiquinone allows calculation of the Km for endogenous CoQ of glycerol-3-phosphate dehydrogenase of 3.14 mM. The results of this investigations reveal that CoQ behaves as a homogeneous pool between glycerol-3-phosphate dehydrogenase and complex III in brown adipose tissue mitochondria; moreover, its concentration is far below saturation for maximal electron transfer activity in comparison with other branches of the respiratory chain connected with the CoQ pool. HPLC analysis revealed a lower amount of CoQ in brown adipose mitochondria (0.752 nmol/mg protein) in comparison with mitochondria from other tissues and the presence of both CoQ9 and CoQ10.
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PMID:Coenzyme Q-pool function in glycerol-3-phosphate oxidation in hamster brown adipose tissue mitochondria. 132 18

The influence of continuous gamma irradiation on the lipids of nuclei and chromatin of rat liver at a dose-rate of 0,129 Gy/day for 155 days (a total dose of 20 Gy) and by feeding of ubiquinone-9 has been studied. The amount of phosphatidylcholine with phosphatidylserine and phosphatidyl-ethanolamine in liver nuclei of irradiated rats was found to increase. Ubiquinone-9 had a normalizing effect. A decrease of cardiolipin was observed in the liver chromatin of irradiated rats. The amount of free fatty acids had a tendency to decrease in homogenate, nuclei and liver chromatin of irradiated rats. Ubiquinone was found to increase the amount of free fatty acids up to the control level. The amount of cholesterol in nuclei was increased after irradiation and that in chromatin tended to rise. Ubiquinone-9 significantly decreased the amount of cholesterol in nuclei and chromatin of irradiated rats.
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PMID:[Effects of ubiquinone-9 on lipids of nuclei and chromatin of the rat liver under continuous irradiation]. 142 Dec 18

Dihydroorotate dehydrogenase (DHODase) has been purified 400-fold from the rodent malaria parasite Plasmodium berghei to apparent homogeneity by Triton X-100 solubilization followed by anion-exchange, Cibacron Blue F3GA-agarose affinity, and gel filtration chromatography. The purified enzyme has a molecular mass of 52 +/- 2 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and of 55 +/- 6 kDa by gel filtration chromatography, and it has a pI of 8.2. It is active in monomeric form, contains 2.022 mol of iron and 1.602 acid-labile sulfurs per mole of enzyme, and does not contain a flavin cofactor. The purified DHODase exhibits optimal activity at pH 8.0 in the presence of the ubiquinone coenzyme CoQ6, CoQ7, CoQ9, or CoQ10. The Km values for L-DHO and CoQ6 are 7.9 +/- 2.5 microM and 21.6 +/- 5.5 microM, respectively. The kcat values for both substrates are 11.44 min-1 and 11.70 min-1, respectively. The reaction product orotate and an orotate analogue, 5-fluoroorotate, are competitive inhibitors of the enzyme-catalyzed reaction with Ki values of 30.5 microM and 34.9 microM, respectively. The requirement of the long-chain ubiquinones for activity supports the hypothesis of the linkage of pyrimidine biosynthesis to the electron transport system and oxygen utilization in malaria by DHODase via ubiquinones [Gutteridge, W. E., Dave, D., & Richards, W. H. G. (1979) Biochim. Biophys. Acta 582, 390-401].
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PMID:Purification and characterization of dihydroorotate dehydrogenase from the rodent malaria parasite Plasmodium berghei. 184 78

It was established that ubiquinone-9 (30 mg/kg per course) decreases in rats the content of primary products of lipid peroxidation--diene conjugates--in the liver by 12 times greater than vitamin E (a course dose of 30 mg/kg). Ubiquinone-9, vitamin E and sodium selenite (a course dose of 90 mg/kg) equally reduced the content of a secondary product of lipid peroxidation--malon dialdehyde. In this case the activity of sodium selenite was 300 times higher than the activity of ubiquinone-9 and vitamin E. The use of ubiquinone-9 in combination with vitamin E and sodium selenite potentiated the antioxidant effect.
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PMID:[Antioxidant activity of ubiquinone-9 and its combinations with vitamin E and sodium selenite in toxic lesions of the liver]. 254 27

Ubiquinone-9, an ubiquinone with a side-chain containing 9 prenyl residues, was purified from Hyphomicrobium spec. strain ZV 580, and identified by thin-layer chromatography, UV spectroscopy, and mass spectrometry. The participation of the quinone in the reactions of the respiratory chain was established by observing its increasing reduction in a membrane fraction upon the addition of NADH, the exhaustion of oxygen, and in the presence of NADH plus cyanide. The degrees of reduction in these states matched those of the cytochromes b and c.
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PMID:Respiratory ubiquinone-9 from Hyphomicrobium spec. Strain ZV 580. 626 32

Hexahydroubiquinone-4 (H6CoQ4) and ubiquinone-9 (CoQ9) in the form of solutions in vegetable oil administered to mice and rats subcutaneously and intragastrically produced a radioprotective effect comparable with that of cystamine. Under the accepted experimental conditions the compounds did not produce any therapeutic effect.
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PMID:[Protective and therapeutic properties of the ubiquinones H6CoQ4 and CoQ9 in gamma irradiation]. 665 62

It is shown that E-hypovitaminosis-induced muscular dystrophy in rabbits is accompanied by a sharp decrease in the body mass, an increase in the urine creatine-index, a decrease in the vitamin E and ubiquinone contents in the liver and skeletal muscle tissues. In the myocardium mitochondria a decrease in the vitamin E content and an increase in the ubiquinone content are observed. The activity of NADH-cytochrome c-, NADH-ubiquinone- and succinate-ubiquinone-reductase also varies in mitochondria of the studied tissues. In myocardium organellas a direct dependence is found between the content of ubiquinone, NADH- and succinate-ubiquinone-reductase activity and an inverse one-between its content and the activity of the NADH-cytochrome c-reductase system. It is established that p-oxybenzoic acid as well as vitamin E prevents development of muscular dystrophy and causes changes analogous in direction in the activity of the ubiquinone-dependent enzymic systems of mitochondria. Ubiquinone-9 is less efficient in preventing the development of muscular dystrophy.
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PMID:[Efficiency of ubiquinone and p-oxybenzoic acid in prevention of E-hypovitaminosis-induced development of muscular dystrophy]. 729 23

The system of perfusing rat livers has been used to evaluate the uptake and incorporation of liposomal CoQ10 into mitochondria. After 90 minutes of perfusion the cells are strongly enriched in CoQ10 up to levels of the same order of magnitude as CoQ9. Heavy and light mitochondrial crude subcellular fractions, low in CoQ10 in control livers, contain high amounts of the quinone after perfusion; yet the purification of these fractions on a metrizamide gradient reveals that the exogenous quinone is mainly associated with the light mitochondrial subfraction, enriched in lysosomes. An increase of the NAD-dependent glutamate-malate oxidase activity is observed in CoQ10 perfused animals. As the total levels of CoQ9 + CoQ10 in these animals are not significantly modified by the CoQ10 incorporated, the observed higher activity is not ascribable to an integration of exogenous quinone into the ubiquinone pool. An antioxidant effect of extramitochondrial CoQ10 on mitochondrial functions is suggested.
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PMID:Uptake and distribution of exogenous CoQ in the mitochondrial fraction of perfused rat liver. 775 44

Ubiquinone (coenzyme Q, CoQ) was analyzed and individual homologues quantified in 11 species of parasitic and free-living protozoa by a combination of thin-layer chromatography and high performance liquid chromatography. Fast atom bombardment ionization-mass spectrometry was used for the first time to confirm the identity of the fractionated CoQ homologues and proved to be a fast, gentle and convenient method for ubiquinone identification. Ubiquinone was detected in all organisms including those devoid of identifiable mitochondria. However, significantly lower levels of CoQ were present in those organisms lacking this respiratory organelle (5- to 50-fold lower in Entamoeba histolytica (CoQ9) and 15- to 350-fold for Giardia lamblia (CoQ9) and Tritrichomonas foetus (CoQ10)). Coenzyme Q9 was the predominant homologue in promastigotes of Leishmania donovani and Leishmania major. Lower amounts of CoQ8 and CoQ10 were also detected in L. donovani, and CoQ8 in L. major. Comparison of the in vitro cultivated promastigote and amastigote forms of Leishmania pifanoi and Leishmania amazonensis revealed CoQ9 to be the sole detectable ubiquinone homologue in the amastigote (macrophage) stage, whereas CoQ8 and CoQ10 were also present in the promastigotes (life cycle stage found in the insect gut) of L. pifanoi, and CoQ7 and CoQ8 in promastigotes of L. amazonensis. Interestingly, the total amounts of CoQ were similar in both forms of these organisms. The free-living ciliates, Tetrahymena thermophila and Paramecium tetraurelia contained CoQ8 as the predominant ubiquinone species and this homologue was also present in the isolated cilia from P. tetraurelia. The marine ciliate, Parauronema acutum contained CoQ7 as well as CoQ8. Comparison of xenosome-containing P. acutum with organisms lacking the symbiont revealed that twice the level of CoQ8 was present in cells grown with this cytoplasmic gram-negative bacterium. Results suggest that CoQ is ubiquitous amongst the protozoa, regardless of the presence of mitochondria, and may function in alternative roles to that of mitochondrial electron transport chain component.
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PMID:Detection of ubiquinone in parasitic and free-living protozoa, including species devoid of mitochondria. 796 63


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