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. The proton-translocating adenosine triphosphatase (ATPase) of bovine heart mitochondria was highly purified by extraction of submitochondrial particles with cholate, fractionation with ammonium sulfate, and sucrose gradient centrifugation in the presence of methanol, deoxycholate, and lysolecithin. 2. The preparation had a very low content of phospholipids, respiratory components, and adenine nucleotide transporter. The ATPase activity (14 o 16 micromoles/min/mg at 30 degrees) was dependent on addition of phospholipids. The purified enzyme was reconstituted with phospholipids, coupling factor 1 (F1), and the oligomycin sensitivity-conferring protein (OSCP) yielding vesicles with highly active 32Pi-ATP exchange (up to 260 nanomoles/min/mg at 30 degrees), and a proton pump driven by ATP. Site III oxidative phosphorylation was reconstituted when purified cytochrome oxidase was included. 3. The 32Pi-ATP exchange of the reconstituted vesicles was sensitive to both rutamycin and dichylohexylcarbodiimide but the ATPase activity was sensitive to rutamycin and not to dicyclohexylcarbodiimide. 4. In sodium dodecyl sulfate-acrylamide gel scans of the complex, the subunits of F1, OSCP, and three other major bands with apparent molecular weights of 32,000, 23,000, and about 11,000 were noted. Three other minor bands with estimated molecular weights of 80,000, 70,000, and 52,000 were also detected. These bands apparently represent residual trace amounts of respiratory components. Quantitative assays of individual respiratory components revealed between 0 and 3% contamination. 5. We conclude that the rutamycin-sensitive ATPase complex functions as a reversible ATP-driven proton pump.
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PMID:Purification and properties of the proton-translocating adenosine triphosphatase complex of bovine heart mitochondria. 17 16

A phospholipid spin label, 16-doxylphosphatidylcholine, is employed in a study of lipid--protein interactions in cytochrome oxidase containing membranes. Two methods are used to label the membranous cytochrome oxidase: dispersion in cholate with subsequent detergent removal, and fusion with vesicles of the pure phospholipid label in the absence of detergent. A fraction of the label is immobilized, which is calculated to fall in the range of 0.17--0.21 mg of phospholipid/mg of protein (0.15--0.19 after correction for lipids not extracted by chloroform--methanol). This narrow range of values is independent of methods of labeling, protein isolation, and lipid depletion within experimental error. When labeling by fusion is utilized, the patches of pure phosphatidylcholine spin label diffuse in the plane of the bilayer, become diluted, and demonstrate exchange with bound phospholipid. These observations are evidence that boundary lipid, as reflected by the partitioning of the phosphatidylcholine label, is in equilibrium with adjacent bilayer regions and that it consists of a relatively constant amount of phospholipid associated with the hydrophobic portion of the protein.
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PMID:Phosphatidylcholine exchange between the boundary lipid and bilayer domains in cytochrome oxidase containing membranes. 19 26

The ultrastructural localization of the activities of two enzyme systems in the culture forms of Leishmania donovani was shown by means of the diaminobenzidine techniques. The consistent deposition of electron dense reaction product of DAB oxidation without H2O2 in the kinetoplast and mitochondrial cristae and membranes was taken as evidence of the presence of cytochrome oxidase activity and cytochrome c. In the presence of H2O2, a more intense DAB oxidation was attributed to the activity of a peroxidase, possibly cytochrome c peroxidase. Mitochondrial and kinetoplast reactions to DAB were completely inhibited by KCN, methanol-nitroprusside, and by heating to 50 degrees C for 10 min. On the other hand, no inhibitory effect was observed with 100 mM 3-amino-1,2,4-triazole. Under all conditions of incubation tested, the microbodies were completely unreactive to DAB staining, which was utilized as the basis for their identification. These organelles are rounded, moderately electron-opaque bodies with a finely granular matrix and fine tubules or cores and are limited by a single membrane. Under normal staining method, the microbodies were indistinguishable from the rounded sections of mitochondria.
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PMID:Ultrastructural localization of diaminobenzidine reactivity in leishmania donovani promastigotes. 19 23

Pseudomonas AM1 contains cytochromes a, b and c and more than one CO-binding pigment (cytochrome a3, cytochrome c and possibly a cytochrome o). The soluble cytochrome c has been purified; its isoelectric point is low and its molecular weight is 20000. This cytochrome is reduced in whole bacteria by all oxidizable substrates at rates determined by the primary dehydrogenases. A mutant lacking cytochrome c oxidizes all substrates except methanol, ethanol and methylamine; these no longer support growth. The role of cytochrome c in electron transport in Pseudomonas AM1 is discussed.
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PMID:The microbial metabolism of C1 compounds. The cytochromes of Pseudomaonas AM1. 23 91

The cells of methylotrophic bacteria (Achromobacter parvulus 1, Pseudomonas methylica 2 and 20, Ps. fluorescens 45, Ps. oleovorans 52) and Candida methylica 101 grown in a medium with methanol take up oxygen in the presence of formiate. A. parvulus is most resistant to formiate (KM = 2.3 +/- 0.5) X 10(-3) M; Ki = 4 x 10(-1) M). When grown on Cn substrates, these microorganisms cannot oxidize formiate (with an exception of A. parvulus). Formiate also serves as a respiration substrate for E. coli K-12 and the purple bacterium Rhodopseudomonas palustris, disregarding the composition of a medium on which the cells are grown. When the cells cannot oxidize formiate, it inhibits the respiration of the cells and cell extracts in the presence of other substrates, including TMPD + ascorbate. The respiration is completely inhibited at a concentration of formiate of 10(-3)--10(-2) M. It follows therefore that formiate acts on the terminal cytochrome oxidase, regardless of whether it is cytochrome a or o.
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PMID:[Effect of formate on the respiration of different microorganisms]. 48 Dec 74

A test model of studying the effects of chronic pharmacological treatment on cerebral metabolism related to energy transduction was developed. The most useful biochemical parameters were the cerebral enzymatic activities related to the glycolytic pathway (lactate dehydrogenase), the Krebs' cycle (citrate synthetase and malate dehydrogenase) and the electron transfer chain (total NADH-cytochrome c reductase and cytochrome oxidase). The model is based on the natural growth-dependent changes occurring in the rat during aging (from 10 to 60 weeks of life). As test drug, 10-methoxy-1,6-dimethyl-ergoline-8 beta-methanol-(5-bromonicotinate) (nicergoline, Sermion) was administered daily for three periods of 16 weeks each (10-26, or 28-44, or 44-60 weeks of life) by two different administration routes (oral and i.p.), and at two different dose levels: oral 1 or 4, i.p. 0.25 or 1 mg/kg. Biochemical data were obtained blindly after 4, 8, 12 and 16 weeks of treatment. The drug tested exerted different effects which were dependent on the various administration periods and the administration routes. No dose-effect relationship was established.
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PMID:[Cerebral enzymatic activities related to energy transduction processes. A model for the evaluation of pharmacological changes in the brain of the adult rat]. 54 66

Pseudomonas AM1, Hyphomicrobium X and Pseudomonas MS all contain cytochrome a/a(3) and a b-type cytochrome able to react with CO. Pseudomonas AM1 and Hyphomicrobium X also have a CO-binding cytochrome c. The purified cytochrome c (redox potential 0.26V) of Pseudomonas AM1 was not susceptible to oxidation by molecular oxygen. CO reacted slowly with the reduced form giving a CO difference spectrum with a peak at 412nm and troughs at 420nm and 550nm. Similar results were obtained with the cytochrome c of Hyphomicrobium (aerobically grown or anaerobically grown with nitrate) and with that of Pseudomonas extorquens. The results given in the present paper are incompatible with an oxygenase or oxidase function for the soluble cytochrome c of methylotrophs. Studies with whole cells of Pseudomonas AM1 and a cytochrome c-deficient mutant have demonstrated that cytochrome b (redox potential 0.009V) is the first cytochrome in the electron-transport chain for oxidation of all substrates except methanol (and ethanol) whose oxidation does not involve this cytochrome. All substrates are usually oxidized by way of cytochrome c and cytochrome oxidase (cytochrome a/a(3)), but there is an alternative route for the reduction of cytochrome a/a(3) in the mutant lacking cytochrome c. Results of experiments on cyanide inhibition of respiration and cytochrome oxidation support the suggestion that the susceptibility of cytochrome b to oxidation by molecular oxygen (reflected in its ability to react with CO) is probably irrelevant to the normal physiology of Pseudomonas AM1.
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PMID:The microbial metabolism of C1 compounds. The electron-transport chain of Pseudomonas am1. 122 Jun 89

Metabolism of methanol, methyl ethers, esters and amides give rise to formic acid. This acid is an inhibitor of the mitochondrial cytochrome oxidase causing histotoxic hypoxia. Formic acid is a weaker inhibitor than cyanide and hydrosulphide anions. The body burden of formate in methanol poisoning is high enough to cause acidosis, and other clinical symptoms. Part of the protons can be attributed to formic acid whereas the most significant acid load results from the hypoxic metabolism. The acidosis causes e.g. dilatation of cerebral vessels, facilitation of the entry of calcium ions into cells, loss of lysosomal latency and deranged production of ATP. The latter effect seems to impede parathormone-dependent calcium reabsorption in the kidney tubules. Besides, urinary acidification is affected by formic acid. Its excretion causes continuous recycling of the acid by the tubular cell Cl-/formate exchanger. This sequence of events may partially explain an accumulation of formate in urine. Occupational exposure to vapours of methanol and formic acid can be quantitatively monitored by urinary formic acid determinations. Formic acid toxicity may prove a suitable model for agents causing histotoxic hypoxia.
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PMID:Methanol and formic acid toxicity: biochemical mechanisms. 166 61

Paracoccus denitrificans is able to grow on the C1 compounds methanol and methylamine. These compounds are oxidized to formaldehyde which is subsequently oxidized via formate to carbon dioxide. Biomass is produced by carbon dioxide fixation via the ribulose biphosphate pathway. The first oxidation reaction is catalyzed by the enzymes methanol dehydrogenase and methylamine dehydrogenase, respectively. Both enzymes contain two different subunits in an alpha 2 beta 2 configuration. The genes encoding the subunits of methanol dehydrogenase (moxF and moxI) have been isolated and sequenced. They are located in one operon together with two other genes (moxJ and moxG) in the gene order moxFJGI. The function of the moxJ gene product is not yet known. MoxG codes for a cytochrome c551i, which functions as the electron acceptor of methanol dehydrogenase. Both methanol dehydrogenase and methylamine dehydrogenase contain PQQ as a cofactor. These so-called quinoproteins are able to catalyze redox reactions by one-electron steps. The reaction mechanism of this oxidation will be described. Electrons from the oxidation reaction are donated to the electron transport chain at the level of cytochrome c. P. denitrificans is able to synthesize at least 10 different c-type cytochromes. Five could be detected in the periplasm and five have been found in the cytoplasmic membrane. The membrane-bound cytochrome c1 and cytochrome c552 and the periplasmic-located cytochrome c550 are present under all tested growth conditions. The cytochromes c551i and c553i, present in the periplasm, are only induced in cells grown on methanol, methylamine, or choline. The other c-type cytochromes are mainly detected either under oxygen limited conditions or under anaerobic conditions with nitrate as electron acceptor or under both conditions. An overview including the induction pattern of all P. denitrificans c-type cytochromes will be given. The genes encoding cytochrome c1, cytochrome c550, cytochrome c551i, and cytochrome c553i have been isolated and sequenced. By using site-directed mutagenesis these genes were mutated in the genome. The mutants thus obtained were used to study electron transport during growth on C1 compounds. This electron transport has also been studied by determining electron transfer rates in in vitro experiments. The exact pathways, however, are not yet fully understood. Electrons from methanol dehydrogenase are donated to cytochrome c551i. Further electron transport is either via cytochrome c550 or cytochrome c553i to cytochrome aa3. However, direct electron transport from cytochrome c551i to the terminal oxidase might be possible as well.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:C1 metabolism in Paracoccus denitrificans: genetics of Paracoccus denitrificans. 205 Jun 54

The electron transport system (with cytochrome aa3) coupled to the oxidation of methanol in Methylobacterium extorquens AM1 (former Pseudomonas AM1) was reconstituted with highly purified constituents of the system. A mixture of 2.7 microM methanol dehydrogenase, 3.2 microM cytochrome cH, and 71 nM cytochrome c oxidase (= cytochrome aa3) consumed oxygen at a lower rate in the presence of methanol, while its activity was enhanced 3-fold by the addition of 1.4 microM cytochrome cL (74 mol of O2 consumed/mol of heme a of cytochrome c oxidase per min). Further addition of amicyanin to the above mixture did not affect the activity. Although ammonium ion greatly activated the activity of methanol dehydrogenase, the ion had little effect on the oxygen consumption activity of the above mixture. On the basis of the results obtained in the present study, an electron transport system is proposed for the oxidation of methanol in M. extorquens AM1.
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PMID:The methanol-oxidizing system of Methylobacterium extorquens AM1 reconstituted with purified constituents. 216 71


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