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 restriction patterns of mitochondrial DNA from 20 isolates of the two varieties of Cryptococcus neoformans were compared. The patterns exhibited extensive heterogeneity among the isolates regardless of their serotype or varietal status. Hybridizations with cloned fragments of the conserved cytochrome oxidase gene from Saccharomyces cerevisiae exhibited at least seven patterns among the 20 isolates. There were, however, similarities in the restriction patterns among isolates within the same serotype that were not shared by isolates of other serotypes. Intra-varietal similarities were observed in the restriction patterns among the isolates of C. neoformans var. neoformans which were not present in the restriction patterns among the isolates of C. neoformans var. gattii. Hybridization of some cloned mitochondrial DNA fragments to total DNA digests of various isolates revealed polymorphic as well as variety-specific patterns of homology. These findings agree with the antigenic heterogeneity among the isolates and support the current taxonomic classification of C. neoformans into two varieties.
J Gen Microbiol 1989 Dec
PMID:Restriction fragment polymorphism in mitochondrial DNA of Cryptococcus neoformans. 257 73

We have cloned three distinct nuclear genes, NAM1, NAM7, and NAM8, which alleviate mitochondrial intron mutations of the cytochrome b and COXI (subunit I of cytochrome oxidase) genes when present on multicopy plasmids. These nuclear genes show no sequence homology to each other and are localized on different chromosomes: NAM1 on chromosome IV, NAM7 on chromosome XIII and NAM8 on chromosome VIII. Sequence analysis of the NAM1 gene shows that it encodes a protein of 440 amino acids with a typical presequence that would target the protein to the mitochondrial matrix. Inactivation of the NAM1 gene by gene transplacement leads to a dramatic reduction of the overall synthesis of mitochondrial protein, and a complete absence of the COXI protein which is the result of a specific block in COXI pre-mRNA splicing. The possible mechanisms by which the NAM1 gene product may function are discussed.
Mol Gen Genet 1989 Feb
PMID:Novel class of nuclear genes involved in both mRNA splicing and protein synthesis in Saccharomyces cerevisiae mitochondria. 265 95

Thyroidectomy and castration in Calotes versicolor significantly decreased the activities of hepatic mitochondrial cytochrome oxidase, alpha-glycerophosphate dehydrogenase (alpha-GPDH), and succinate dehydrogenase (SDH) when compared to sham-operated controls. Administration of thyroid hormones in thyroidectomized lizards and testosterone in castrated specimens stimulated the activities of all three enzymes studied. Chloramphenicol, when injected with thyroxine prevented the hormone-stimulated activities of cytochrome oxidase and SDH, while actinomycin D and chloramphenicol, when administered along with testosterone propionate (low dose) prevented the testosterone-stimulated activities of cytochrome oxidase and alpha-GPDH.
Gen Comp Endocrinol 1988 Mar
PMID:Influence of thyroid hormones and testosterone on the activities of hepatic mitochondrial enzymes in the Indian garden lizard, Calotes versicolor. 283 60

A cDNA clone derived from the mitochondrial cytochrome oxidase I gene has been used to show that the level of mitochondrially encoded RNA species declines during herpes simplex virus type 2 infection in a manner similar to that for RNA species derived from nuclear genes. In contrast to the situation for nuclear genes, however, no change in the transcription rate of the mitochondrial genome during infection was detected, indicating that post-transcriptional processes alone are responsible for the decline in the levels of mitochondrial RNA species during infection. Two stages in this post-transcriptional degradation have been defined, only one of which is dependent upon viral protein synthesis in the infected cell.
J Gen Virol 1988 Jun
PMID:Effect of herpes simplex virus type 2 infection on mitochondrial gene expression. 283 78

In vivo administration of L-thyroxine (L-T4) in Anabas testudineus, while significantly stimulated the activities of cytochrome c oxidase and alpha-glycerophosphate dehydrogenase (alpha-GPDH), inhibited glucose-6-phosphate dehydrogenase (G-6-PDH), cytosolic and mitochondrial malate dehydrogenase (cyt. MDH; mit. MDH), and Mg2+ DNP-dependent adenosine triphosphatase (Mg2+ ATPase) activities. The activities of lactate dehydrogenase (LDH), succinate dehydrogenase (SDH), and catalase remained unaltered after L-T4 treatment. Administration of protein synthesis inhibitors such as actinomycin D, while significantly inhibited cytochrome oxidase, alpha-GPDH, catalase, SDH, and Mg2+ ATPase activities, did not change LDH, cyt. MDH, and mit. MDH activities. Chloramphenicol injection significantly stimulated cytochrome oxidase, alpha-GPDH, and G-6-PDH activities. Simultaneous injections of actinomycin D or chloramphenicol with 3,5,3'-triiodo-L-thyronine (L-T3) or L-T4 prevented the effects of thyroid hormones on enzyme activities, when compared to the respective controls.
Gen Comp Endocrinol 1989 Jan
PMID:Oxidative metabolism in a teleost, Anabas testudineus Bloch: effect of thyroid hormones on hepatic enzyme activities. 292 Sep 3

This paper considers the way in which the oxygen reaction described by Dr. Nicholls and the ADP control reactions described by Dr. Racker could cooperate to establish a purposeful metabolic control phenomenon in vivo. This has required an examination of the kinetic properties of the respiratory chain with particular reference to methods for determinations of oxygen affinity (K(m)). The constant parameter for tissue respiration is k(1), the velocity constant for the reaction of oxygen with cytochrome oxidase. Not only is this quantity a constant for a particular tissue or mitochondria; it appears to vary little over a wide range of biological material, and for practical purposes a value of 5 x 10(7) at 25 degrees close to our original value (20) is found to apply with adequate accuracy for calculation of K(m) for mammalia. The quantity which will depend upon the tissue and its metabolic state is the value of K(m) itself, and K(m) may be as large as 0.5 microM and may fall to 0.05 microM or less in resting, controlled, or inhibited states. The control characteristic for ADP may depend upon the electron flux due to the cytochrome chain (40); less ADP is required to activate the slower electron transport at lower temperatures than at higher temperatures. The affinity constants for ADP control appear to be less dependent upon substrate supplied to the system. The balance of ADP and oxygen control in vivo is amply demonstrated experimentally and is dependent on the oxygen concentration as follows. In the presence of excess oxygen, control may be due to the ADP or phosphate (or substrate), and the kinetics of oxygen utilization will be independent of the oxygen concentration. As the oxygen concentration is diminished, hemoglobin becomes disoxygenated, deep gradients of oxygen concentration develop in the tissue, and eventually cytochrome oxidase becomes partially and then completely reduced. DPN at this point will become reduced and the electron flow diminished. The rate of ATP production falls and energy conservation previously under the control of the ADP concentration will now be controlled by the diffusion of oxygen to the respiratory enzymes in the mitochondria. Under these conditions the rate of reaction of cytochrome oxidase with oxygen and the reaction of cytochromes with one another become of key importance. The rise of ADP and the depletion of energy reserves evoke glycolytic activity, and failure of biological function may result.
J Gen Physiol 1965 Sep
PMID:Reaction of oxygen with the respiratory chain in cells and tissues. 428 27

A comprehensive survey of the interaction of the copper proteins and oxygen is presented including a correlation of structure, function, and other properties of the known copper oxidases and of hemocyanin. The origin of their blue color and the structure of copper complexes and copper proteins are related to the oxidation state of copper ion and relevant electronic transitions probably arising from the formation of charge transfer complexes. The oxygen reactions of hemocyanin, ceruloplasmin, and cytochrome oxidase show half-saturation values far below the other Cu enzymes. The formation of hydrogen peroxide as a reaction product is associated with the presence of one Cu atom per oxidase molecule or catalytic system. Water is the corresponding product of the other Cu oxidases with four or more Cu atoms per molecule, except for monoamine oxidase. Mechanisms for the oxidase action of the two and four electron transfer Cu oxidases and tyrosinase are proposed. These reactions account for the number, the oxidation-reduction potential, and the oxidation state of Cu in the resting enzyme, the cyclical change from Cu(II) to Cu(I), the diatomic nature of O(2), the sequence of the oxidation and reduction reactions, and other salient features. The catalytic reactions involved in the oxidation of ascorbic acid by plant ascorbate oxidase, ceruloplasmin, and Cu(II) are compared. Finally the substrate specificity, inhibitory control, and the detailed mechanism of the oxidase activity of ceruloplasmin are summarized.
J Gen Physiol 1965 Sep
PMID:Copper proteins and oxygen. Correlations between structure and function of the copper oxidases. 428 28

The mitochondrial genome from Cyprinus carpio oocytes is a 10.5 megadalton, circular DNA molecule. The carp mitochondrial DNA was cloned in pBR325. Three recombinant plasmids accounted for the entire genome. Mapping of this DNA using 11 different restriction endonucleases is reported here. Both the large and small rRNA genes were then localized using Southern blot analysis. The subunit I of the cytochrome oxidase, the cytochrome b, the tRNAGlu and the URF 4 genes were localized by nucleotide sequence analysis and homology studies with human mtDNA. Our results suggest that a similar gene order has been maintained in the mitochondrial genomes of Chordata and support the hypothesis of a common ancestor for all vertebrate organelle genomes. This study constitutes the first report on the genome organization of a fish mtDNA and provides information for further investigation in connection with sequence determination, replication, and gene expression in carp mitochondria.
Mol Gen Genet 1984
PMID:Cloning, physical mapping and genome organization of mitochondrial DNA from Cyprinus carpio oocytes. 609 Aug 66

Germinating spores of Micromonospora chalcea pass through three morphological stages: darkening, swelling and germ tube emergence. The process of germination has pH and temperature optima of 8.0 and 40 degrees C, respectively, and is not affected by activation treatments. Darkening, accompanied by a loss of heat resistance and refractility and a decrease in absorbance of the dormant spores, needs only energy, which can be obtained from endogenous sources, and exogenous cations. Agents that inhibit ATP formation block darkening, but inhibitors of macromolecular synthesis do not affect it. Swelling requires exogenous carbon but not nitrogen sources and is characterized by a 30 to 40% increase in spore diameter. RNA synthesis is necessary for swelling and inhibitors of protein synthesis delay this process. During this stage, maximum respiratory, cytochrome oxidase and catalase activities are reached. DNA synthesis starts at the beginning of germ tube emergence. This final stage requires both exogenous carbon and nitrogen sources and the sequence of macromolecular synthesis is RNA, protein and, finally, DNA. Rifampicin, streptomycin and mitomycin C prevent protein and DNA synthesis regardless of when added during germination. Rifampicin inhibits [3H]uridine incorporation immediately but there is a delay of about 160 min in the case of streptomycin or mitomycin C.
J Gen Microbiol 1980 Nov
PMID:Germination of spores of Micromonospora chalcea: physiological and biochemical changes. 616 28

Partial suppressors of a mitochondrially inherited mutation, [cs-67], conferring cold-sensitivity at 20 degrees C were identified. These mapped at one mitochondrial and four unlinked nuclear loci. Most suppressors partially restored the cytochrome aa3 deficiency of the cold-sensitive strain at 20 degrees C. Strains carrying two or more suppressors and [cs-67] showed considerably impaired growth. This effect was temperature-dependent, being more severe at 37 degrees C, and was not expressed in the presence of the [cs-67+] allele. The cytochrome oxidase activity of one of these strains was no more heat-sensitive than that of the wild-type implying that these mutations did not directly modify cytochrome oxidase. The wild-type strain grown in the presence of chloramphenicol and the cold-sensitive strain grown at 20 degrees C had similar cytochrome spectra and mitochondrial membrane protein profiles on sodium dodecyl sulphate gradient acrylamide gels. [cs-67] conferred pleiotropically a low level of resistance to paramomycin at 37 degrees C. It is suggested that [cs-67] and the suppressors act at the level of the mitochondrial ribosome.
J Gen Microbiol 1980 Aug
PMID:Nuclear and mitochondrial suppression of a mitochondrially inherited cold-sensitive mutation in Aspergillus nidulans. 626 32


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