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

---

Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have cloned and sequenced COX12, the nuclear gene for subunit VIb of Saccharomyces cerevisiae cytochrome c oxidase. This subunit, which was previously not found in cytochrome c oxidase purified from S. cerevisiae, has a deduced amino acid sequence which is 41% identical to the sequences of subunits VIb of bovine and human cytochrome c oxidases. The chromosomal copy of COX12 was replaced with a plasmid-derived copy of COX12, in which the coding region for the suspected cytochrome oxidase subunit was replaced with the yeast URA3 gene. The resulting Ura+ deletion strain grew poorly at room temperature and was unable to grow at 37 degrees C on ethanol/glycerol medium, whereas growth was normal at both temperatures on dextrose. This temperature-dependent, petite phenotype of the deletion strain was complemented to wild-type growth with a single copy plasmid carrying COX12. Cytochrome c oxidase activity in mitochondrial membranes from the cox12 deletion strain is decreased to 5-15% of that in membranes from the wild-type parent, and this activity is restored to normal when the cox12 deletion strain is complemented by the plasmid-borne COX12. Optical spectra of mitochondrial membranes from the cox12 deletion strain revealed that optically detectable cytochrome c oxidase is assembled at room temperature and at 37 degrees C, although the heme a + a3 absorption is diminished approximately 50%. The N-terminal amino acid sequence of the protein encoded by COX12 is identical to the N-terminal sequence of a subunit found in yeast cytochrome c oxidase purified by a new procedure (Taanman, J.-W., and Capaldi, R. A. (1992) J. Biol. Chem. 267, 22481-22485). We conclude that COX12 encodes a subunit of yeast cytochrome c oxidase which is essential during assembly for full cytochrome c oxidase activity but apparently can be removed after the oxidase is assembled, with retention of oxidase activity. This is the first instance in which deletion of a subunit of cytochrome c oxidase results in assembly of optically detectable cytochrome c oxidase but having markedly diminished activity.
...
PMID:Isolation and characterization of COX12, the nuclear gene for a previously unrecognized subunit of Saccharomyces cerevisiae cytochrome c oxidase. 133 Oct 57

The coxII/coxIII operon of Rhodobacter sphaeroides cytochrome c oxidase has been sequenced and characterized by insertional inactivation/complementation analysis. The organization of the genes in this locus (coxII.orf1.orf3.coxIII) is the same as that of the equivalent operon of Paracoccus denitrificans (ctaC.ctaB.ctaG.ctaE), but unlike that of other bacteria whose cytochrome oxidase genes have been characterized so far. The predicted amino acid sequence homology with eukaryotic oxidases is also higher for Rb. sphaeroides (and P. denitrificans) than for other bacterial versions of the enzyme. The inactivation of coxII results in loss of the characteristic cytochrome oxidase spectrum from membranes of the mutant strain. Full recovery requires introduction into the bacterium of the complete operon containing coxII.orf1.orf3.coxIII; partial complementation yielding a spectrally altered enzyme is achieved with a plasmid containing coxII or coxII.orf1.orf3. These results indicate that the peptides ORF1, ORF3, and COXIII are all required for assembly of native cytochrome c oxidase, suggesting an oxidase-specific assembly or chaperonin function for the ORFs in Rb. sphaeroides similar to that observed for the homologous gene products in yeast, COX10 and COX11.
...
PMID:Cytochrome aa3 of Rhodobacter sphaeroides as a model for mitochondrial cytochrome c oxidase. The coxII/coxIII operon codes for structural and assembly proteins homologous to those in yeast. 133 50

Seven cytochromes c, in which individual lysines have been modified to the propylthiobimane derivatives, have been prepared. These derivatives were also converted to the porphyrin cytochromes c by treatment with HF. The properties of both types of modified proteins were studied in their reactions with cytochrome c oxidase. The results show that lysines 25, 27, 60, 72, and 87 do not contribute a full charge to the binding interaction with the oxidase. These five residues, with the exception of the lysine-60 derivative, on the front surface of the protein and contain the solvent-accessible edge of the heme prosthetic group. By contrast, lysines 8 and 13 at the top of the front surface do contribute a full charge to the binding interaction with the oxidase. The removal of the positive charge on any one lysine weakens the binding to cytochrome c oxidase by at least 1 kcal (1 cal = 4.1868 J). The presence of bimane at lysines 13 and 87 clearly forces the separation of the cytochrome c and oxidase, but this does not occur with the other complexes. The bimane-modified lysine-13 protein, and to a lesser extent that modified at lysine 8, show the interesting effect of enhanced complex formation with cytochrome c oxidase when subjected to pressure, possibly because of entrapment of water at the newly created interface of the complex. Our observations indicate that the two proteins of the cytochrome c - cytochrome oxidase complex have preferred, but not obligatory, spatial orientations and that interaction occurs without either protein losing significant portions of its hydration shell.
...
PMID:Cytochrome c and cytochrome c oxidase interactions: the effects of ionic strength and hydrostatic pressure studied with site-specific modifications of cytochrome c. 133 34

The redox state of cytochrome alpha 3 during in situ respiration of leaves of 20-day-old rice seedlings was assessed by in vivo aerobic assay of nitrate reductase, after 1 min exposure to carbon monoxide. Different stress treatments like water and salt stresses, disintegration of leaf tissues and darkness modified the redox state of cytochrome c oxidase. The dark treatment altered the redox state of cytochrome oxidase from reduced to the oxidized state, as judged by its reaction with CO in CO-sensitive rice cultivar. The water and salt stresses as well as the disintegration of leaf tissue on the contrary altered cytochrome oxidase from the oxidized to its reduced state in CO-insensitive cultivars; probably by changing the cellular integrity, turgidity and structure of mitochondrial membrane, and also due to decreased mitochondrial energization.
...
PMID:Modification of the redox state of cytochrome c oxidase of rice due to certain stress treatments. 133 47

Cytochrome oxidase is extremely susceptible to modifications that could occur at membrane level such as, for example, the deep influence that cardiolipin has on its maximal activity. Moreover, even the different ratio of fatty acid species in cardiolipin molecule could affect cytochrome oxidase properties. The influence of dietary fat and of endogenous lipid peroxidation with regard to cytochrome c oxidase activity and cytochrome a+a3 concentrations in mitochondria from rat heart has been investigated. Whilst the endogenous oxidative stress led to increase the peroxidation products, detected by means of hydroperoxides and conjugated dienes determinations, the features of the lipid environment were not affected as shown by fluorescence polarization technique. However, the oxidative stress was able to induce a significant increase of cytochrome a+a3 level even if the phenomenon did not reach the same extent as in the case of previous investigations on rat liver. Moreover, the results vary with the different fat source used and this might indicate a possible involvement of different dietary fats in peroxidation mechanisms. Furthermore the data we have obtained enable us to confirm once more that an induction of the synthesis of cytochrome a+a3 might be related to an enhanced production of peroxides at membrane level.
...
PMID:[Cytochrome oxidase induction following oxidative stress produced by adriamycin in the heart of rats fed olive oil]. 133 77

The 1:1 complex between horse heart cytochrome c and bovine cytochrome c oxidase, and between yeast cytochrome c and Paracoccus denitrificans cytochrome c oxidase have been studied by a combination of second derivative absorption, circular dichroism (CD), and resonance Raman spectroscopy. The second derivative absorption and CD spectra reveal changes in the electronic transitions of cytochrome a upon complex formation. These results could reflect changes in ground state heme structure or changes in the protein environment surrounding the chromophore that affect either the ground or excited electronic states. The resonance Raman spectrum, on the other hand, reflects the heme structure in the ground electronic state only and shows no significant difference between cytochrome a vibrations in the complex or free enzyme. The only major difference between the Raman spectra of the free enzyme and complex is a broadening of the cytochrome a3 formyl band of the complex that is relieved upon complex dissociation at high ionic strength. These data suggest that the differences observed in the second derivative and CD spectra are the result of changes in the protein environment around cytochrome a that affect the electronic excited state. By analogy to other protein-chromophore systems, we suggest that the energy of the Soret pi* state of cytochrome a may be affected by (1) changes in the local dielectric, possibly brought about by movement of a charged amino acid side chain in proximity to the heme group, or (2) pi-pi interactions between the heme and aromatic amino acid residues.
...
PMID:Electronic and vibrational spectroscopy of the cytochrome c:cytochrome c oxidase complexes from bovine and Paracoccus denitrificans. 133 46

This work reviews the role of mitochondria in the ageing process and summarizes pathomorphological biochemical and molecular genetic data. The pathophysiological mechanisms underlying the phenomenon of ageing are only partly understood. There is, however, increasing evidence that mitochondria are essentially involved. In various tissues of various species a decline in the respiratory chain capacity is seen with ageing. Enzyme histochemistry of cytochrome c oxidase (complex IV of the respiratory chain) has revealed an age-related increase of randomly distributed defective fibres/cells in the skeletal and heart muscle the random pattern probably indicating cellular heterogeneity of the ageing process. Observed deletions of mitochondrial DNA during ageing may represent one causative factor. Similar to primary mitochondrial myopathies point mutations and depletion of the mtDNA are probably also involved. There is some evidence that damage of the mitochondrial genome and of other mitochondrial structures might be due to increased oxygen radical production during ageing. The role of nuclear influences on the degeneration of mitochondrial function remains, however, also to be determined. Nevertheless, the decline of respiratory chain function with ageing represents an important factor for the decline of functional organ reserve capacity in senescence.
...
PMID:Mitochondria and ageing. 134 56

Quantitative histochemistry (scanning microphotometry) was used to determine the activities of the mitochondrial enzymes NAD-linked isocitrate dehydrogenase (EC 1.1.1.41), L-glutamate dehydrogenase (EC 1.4.1.3) and GABA transaminase (EC 2.6.1.19) in various layers of the hippocampus (middle one third) of young (3-4 months old) and memory-impaired aged rats (28-30 months old). For comparison, determinations of cytochrome c oxidase (EC 1.9.3.1) as a marker for mitochondria and energy metabolism were also performed. The study showed that there was a layered reaction pattern in the hippocampus and that the cellular distribution and the levels of enzyme activity were different. However, the activities of the different enzymes (excepting GABA transaminase and cytochrome c oxidase) were significantly correlated in the hippocampus in both age groups. Age-dependent changes were only observed for NAD-linked isocitrate dehydrogenase and GABA transaminase (significant increases of activities in some layers of the hippocampus, preferentially in the terminal field of the perforant path). From the present study it is concluded that, 1. the enzymatic complement of mitochondria in neurons and glia depends upon layer specific metabolic processes of the hippocampus (also with respect to glutamatergic and GABAergic terminal fields) indicating a layer specific interaction of the enzymes studied to produce or catabolize glutamate and GABA, and 2. the age dependent changes of the studied enzymes are very restricted.
...
PMID:Mitochondrial enzymes related to glutamate and GABA metabolism in the hippocampus of young and aged rats: a quantitative histochemical study. 134 64

The operon coding for a respiratory quinol oxidase was cloned from thermoacidophilic archaebacterium Sulfolobus acidocaldarius. It contains three genes, soxA, soxB and soxC. The first two genes code for proteins related to the cytochrome c oxidase subunits II and I, respectively. soxC encodes a protein homologous to cytochrome b, which is a subunit of the mitochondrial and bacterial cytochrome c reductases and the chloroplast cytochrome b6f complex. soxA is preceded by a promoter and the genes are cotranscribed into a 4 kb mRNA. Their protein products form a complex which has been partially purified and has quinol oxidase activity. The reduced minus oxidized absorption spectrum of the complex has two maxima at 586 and 606 nm. The latter is typical of cytochrome c oxidase. The complex contains four haems A. Two haems belong to the 'cytochrome oxidase' part of the complex and two are probably bound to be apocytochrome b (SoxC) and responsible for the 586 nm absorption peak. The homology between the sox gene products and their mitochondrial counterparts suggests that energy conservation coupled to the quinol oxidation catalysed either by the Sulfolobus oxidase or two mitochondrial respiratory enzymes may have a similar mechanism.
...
PMID:An archaebacterial terminal oxidase combines core structures of two mitochondrial respiratory complexes. 137 50

C/57 black mice were immunized with beef heart cytochrome c oxidase, generating 48 hybrid cell lines that secrete antibodies against the different subunits of the enzyme. Immunoblot analysis showed reactions with 7 of the 13 subunits. Among the monoclonal antibodies produced, only those to subunit II gave significant inhibition; these inhibited the enzyme activity completely and prevented cytochrome c binding to the enzyme. Epitope mapping studies indicate that a peptide including residues 200-227 reacts with the antibody, suggesting that the C-terminus of the protein is essential for the binding of this antibody. The carboxyl modifying reagent 1-ethyl-3-[3-(trimethylammonio)propyl]carbodiimide (ETC) was chosen to investigate further the relationship between antibody and cytochrome c binding domains. ETC caused 50% inhibition of the enzyme activity with a first-order time during the first 20 min; a slower reaction over 3 h resulted in 90% inhibition. Cytochrome c binding to the oxidase was inhibited to a similar extent as cytochrome c oxidation, and protection against both effects was afforded by the presence of cytochrome c during ETC modification. Anion-exchange of FPLC of the modified forms of cytochrome oxidase revealed extensive inhomogeneity, indicating random derivatization of a number of different carboxyls even during the first-order reaction, and precluding identification of carboxyl residues related to a specific phase of the reaction. Cytochrome c and the subunit II-specific antibody protected against radioactive labeling of subunit II by ETC in the presence of [14C]glycine ethyl ester, demonstrating that the antibody and cytochrome c occupy significant and overlapping areas on the subunit II surface.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Interaction of cytochrome c with cytochrome c oxidase studied by monoclonal antibodies and a protein modifying reagent. 138 85


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---