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)

Cell lines resistant to ethidium bromide have been developed from cultured mammalian BHK21/C13 cells and these same cells transformed by Rous sarcoma virus (C13/B4). Cells resistant to 2 micrograms ethidium bromide per milliliter have been cloned. One clone of the control and one of the virus-transformed cell lines has been employed for characterization. The resistant cells, in the presence of 2 micrograms ethidium bromide/ml, grow at approximately the same rate as the untreated parental cells. The control cells possess a "normal" karyotype (44 chromosomes), while the corresponding ethidium bromide mutant has a reduced chromosome number of 41 and a number of translocations. The mitochondria displayed morphological alterations compared to the parental lines during the transition phase prior to the isolation of the ethidium bromide-resistant cells. The mitochondria of the ethidium bromide-resistant mutants appear somewhat enlarged with a normal morphology. The effect of ethidium bromide on selected respiratory enzymes in normal and virus-transformed ethidium bromide-resistant baby hamster kidney cells was determined. Ethidium bromide-resistant cells exhibited a depressed level of cytochrome aa3. This depression could not be reversed by growth in ethidium bromide-free media. Ethidium bromide-resistant cells possessed the same cytochrome b, c, and c1 levels per cell as their corresponding parental lines. Purified mitochondria isolated from virus-transformed ethidium bromide-resistant cells exhibited a depression in cytochrome oxidase-specific activity, while the ethidium bromide-resistant control cells did not. All cell lines studied showed a depression in NADH-ferricyanide and NADH-cytochrome c reductase-specific activities relative to their parental BHK21/C13 cells. No increase was observed in virus-transformed ethidium bromide-resistant cells. Ethidium bromide-resistant control cells exhibited a two-fold increase in oligomycin-insensitive adenosine triphosphatase activity relative to their parental cells. All of the cell lines studied possessed equivalent oligomycin-sensitive adenosine triphosphatase-specific activity except for the virus-transformed, dye-resistant mutant, whose activity was increased.
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PMID:Control and virus-transformed baby hamster kidney cells resistant to ethidium bromide. I. Characterization and the respiratory enzymes. 625 Oct 98

A 1-month-old boy was admitted because of failure to thrive. He was floppy and had bilateral ptosis, diminished reflexes, and poor suck. He had aspiration pneumonia, developed seizures, and died at age 3 1/2 months. Laboratory data showed lactic acidosis, proteinuria, glycosuria and generalized aminoaciduria. He was an only child, and family history was negative. Muscle biopsy showed large clumps of granules positive with oxidative enzyme stains and increased lipid droplets. Ultrastructural studies showed large aggregates of mitochondria, many of which were greatly enlarged and contained disoriented or concentric whorls of cristae and paracrystalline inclusions. Cytochrome c oxidase was absent in fresh frozen sections by histochemical staining. By biochemical assay, cytochrome c oxidase (cytochrome aa3) was 6% of normal in muscle biopsy and undetectable in autopsy muscle; spectra and content of cytochromes showed lack of cytochrome aa3, decreased cytochrome b and normal cytochrome cc1. In kidney, cytochrome-c-oxidase activity was 38% of normal and spectra showed decreased cytochromes aa3 and b. The association of fatal infantile mitochondrial myopathy, lactic acidosis and renal dysfunction was previously reported by Van Biervliet et al and appears to be a distinct nosologic entity, one of the few biochemically defined mitochondrial myopathies.
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PMID:Fatal infantile mitochondrial myopathy and renal dysfunction due to cytochrome-c-oxidase deficiency. 625 6

Studies of hepatic submitochondrial particles, which provide an experimental system allowing direct measurements of electron transfer independent of substrate transport reactions, showed that chronic ethanol ingestion (36% calories, 40 days) lowered the specific respiratory rates associated with substrate oxidation. NADH oxidase activity was decreased about 40%, succinoxidase was decreased 25%, and oxidation in ascorbate mediated by phenazine methosulfate was decreased 20%. The content of dithionite-reducible cytochrome aa3 was decreased 38%, while that of cytochrome b was decreased 8%, and that of cytochromes c + c1 was decreased 14%. Steady state kinetic measurements indicated that the turnover number of cytochrome oxidase was unchanged, about 15 s-1 under uncoupled conditions with NADH as substrate. When electron flux to cytochrome c was maximal, cytochrome c was maintained in a more highly reduced state relative to cytochrome aa3 in submitochondrial particles from the ethanol-treated rat compared to those from the control rat. This finding is consistent with the greater decrease in cytochrome aa3 content relative to that of cytochrome c. The results indicate that the diminished content of cytochrome oxidase is one of the factors responsible for the lower respiration rates caused by chronic ethanol consumption.
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PMID:Effects of chronic ethanol consumption on the respiratory chain of rat liver submitochondrial particles. 625 68

A hybridization method has been employed to study the organization of the mitochondrial genome of Neurospora crassa. The method involves the use of 5' end-labeled single-stranded restriction fragments obtained from cytoplasmic "petite" strains of Saccharomyces cerevisiae known to contain single mitochondrial genes. The presence and localization of genes homologous to Subunits 1, 2, and 3 of cytochrome oxidase, cytochrome b and Subunit 6 of the ATPase is thus established for the mitochondrial genome of N. crassa.
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PMID:Mapping of mitochondrial structural genes in Neurospora crassa. 625 81

Mitochondrial adenosine triphosphatase isolated from a double mutant of Saccharomyces cerevisiae lacking cytochrome b apoprotein and subunit II of cytochrome oxidase does not contain the mitochondrial translation product (approximate molecular weight, 32,000) previously suggested to be a subunit of the enzyme complex.
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PMID:The largest mitochondrial translation product copurifying with the mitochondrial adenosine triphosphatase of Saccharomyces cerevisiae is not a subunit of the enzyme complex. 626 Jul 57

The biosynthesis of mammalian mitochondrial cytochromes was explored in primary hepatocyte cultures. When these were pulsed with [35S]methionine in the presence of cycloheximide, eight discrete mitochondrial polypeptides were detected by fluorography after their resolution under denaturing conditions by polyacrylamide gel electrophoresis. Since the pulse labeling of the polypeptides was sensitive to chloramphenicol, an inhibitor of mitochondrial translation, they must be translated on mitochondrial ribosomes. Three were identified as the largest subunits of cytochrome oxidase by their immunoprecipitation with antibody directed against purified rat liver cytochrome oxidase. Another (Mr = 28,000) was identified as one of eight subunits of purified rat liver cytochrome b-c1 complex by its immunoprecipitation with antibody directed against bovine heart b-c1 complex. Since cytochrome b apoprotein is the only product of the mitochondrial genome in the yeast cytochrome b-c1 complex (Krieke, J., Bechmann, H., van Hemert, F. J., Schweyan, R. J., Boer, P. H., Kaudewitz, F., and Groot, G. S. P. (1979) Eur. J. Bio-chem. 101, 607-617), the results strongly suggest that the Mr = 28,000 subunit of liver b-c1 complex is cytochrome b apoprotein. Thus the contribution of the mitochondrial translation system to the cytochrome complexes in liver is identical to that of yeast and Neurospora, and there appears to be no deletion or transfer to the nuclear genome of structural genes for mitochondrially synthesized cytochromes during eukaryotic evolution.
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PMID:Site of synthesis of the mitochondrial cytochromes in hepatocyte cultures. 626 20

We have established the DNA sequence of two cis-dominant mutations located in the fourth intron, a14, of the yeast mitochondrial gene oxi3. These mutations prevent the synthesis of subunit I of cytochrome oxidase. Both mutations affect a very short DNA sequence located several hundred base pairs from the intron-exon junctions. An identical sequence is found in the cob-box gene; and this sequence is critical for the excision of the cytochrome b intron. Our interpretation is that this short sequence represents a common signal that must be recognized by the box7-encoded mRNA maturase, in conjunction with the mitochondrial ribosome, to splice out the introns in the two nonhomologous genes, cob-box and oxi3.
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PMID:Critical sequences within mitochondrial introns: cis-dominant mutations of the "cytochrome-b-like" intron of the oxidase gene. 628 71

1. The cytochrome content of beef liver mitochondria differs from that of beef heart mitochondria by an eightfold lower cytochrome aa3 and a twofold lower cytochrome b and c + c1 content. 2. The kinetic properties of cytochrome c oxidases from beef liver and heart were measured with intact cytochrome c-depleted membranes, deoxycholate-dissolved membranes, and with the isolated enzymes at various cytochrome c concentrations with an oxygen electrode. Under all conditions a higher V was found for the liver enzyme, both for the low-affinity and for the high-affinity binding site for cytochrome c. Differences were also found for the Km of the two enzymes. 3. Isolated beef heart mitochondria contained about twice as much cardiolipin than beef liver mitochondria. The isolated enzymes contained one mole cardiolipin per mole of the heart enzyme, but 2 moles cardiolipin per mole of the liver enzyme. 4. By application of a high performance sodium dodecylsulfate gel electrophoretic system the two isolated enzymes could be separated into 13 different protein components, three of which (polypeptides VIa, VIIa and VIII) were found to differ in their apparent molecular weights. The functional meaning of cytochrome c oxidase isoenzymes in liver and heart is discussed.
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PMID:Kinetic and structural differences between cytochrome c oxidases from beef liver and heart. 628 12

Membranes from free-living Rhizobium japonicum were isolated to study electron transport components involved in H2 oxidation. The H2/O2 uptake rate ratio in membranes was approximately 2. The electron transport inhibitors antimycin A, cyanide, azide, hydroxylamine, and 2-n-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited H2 uptake and H2-dependent O2 uptake significantly. H2-reduced minus O2-oxidized absorption difference spectra revealed peaks at 551.5, 560, and 603 nm, indicating the involvement of cytochromes c, b, and a-a3, respectively. H2-dependent cytochrome reduction was completely inhibited in the presence of 0.15 mM HQNO. This inhibition was relieved by the addition of 0.1 mM menadione. Evidence is presented for the involvement of two b-type cytochromes in H2 oxidation. One b-type cytochrome was not reduced by ascorbate and had an absorption peak at 560 nm. The reduction of this cytochrome by H2 was not inhibited by cyanide. A second b-type cytochrome, cytochrome b', was not reduced by H2 in the presence of cyanide. This cytochrome had an absorption peak at 558 nm. Carbon monoxide difference spectra with H2 as reductant provided evidence for the involvement of cytochrome o as well as cytochrome a3 in H2 oxidation. H2 uptake activity in cell-free extracts was inhibited by UV light irradiation. Most of the activity of the UV-treated extracts was restored with the addition of ubiquinone. The restored activity was inhibited by cyanide. A branched electron transport pathway from H2 to O2 is proposed.
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PMID:Electron transport components involved in hydrogen oxidation in free-living Rhizobium japonicum. 628 65

1. The obligate methanol-utilising bacterium strain 4025 contains cytochromes b and c. Cytochrome a is never present. 2. The soluble cytochrome c is similar to that from other methylotrophs in reacting (slowly) with carbon monoxide and it can be separated into two types, differing markedly in their isoelectric points. 3. Some of the cytochrome b reacts rapidly with carbon monoxide and is thus the likely cytochrome oxidase (cytochrome o). 4. The partially purified, NAD+-independent methanol dehydrogenase is similar to such enzymes from the other methanol-utilising bacteria in respect of its prosthetic group, dependence on ammonia or methylamine for activity and its wide substrate specificity. 5. The fluorescence seen in colonies of this organism is probably due to a flavin derivative. 6. This study of electron transport components does not shed any light on the unusually high copper requirement shown by this methylotroph.
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PMID:Characterisation of the electron transport chain of an obligate methylotroph, strain 4025. 629 16


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