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

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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)

A model is proposed for the respiratory adaptation to falling oxygen concentration during growth of the microaerophilic bacterium Campylobacter mucosalis. During the early stages of growth, the oxidation of formate is a two-stage branched process involving the production of H2O2 followed by its peroxidatic removal. In later stages of growth, at lower oxygen concentrations, the predominant electron flow is linear to a membrane-bound cytochrome-c oxidase which reduces O2 directly to H2O. Several components of this model have been investigated. H2O2 was produced during formate oxidation and accumulated when electron transfer to the cytochrome-c peroxidase was inhibited. A cytochrome c-553, of the Class 1 types, was purified and shown to be the specific electron donor to both the peroxidase and the membrane-bound oxidase. The levels of this cytochrome c and of the peroxidase were higher in cells harvested early in growth. In later stages of growth, the activity of the membrane-bound oxidase increased. Proton pumping across the membrane was detected with either H2O2 or oxygen as terminal electron acceptor. The novel energy-conserving role of H2O2 in this catalase-negative bacterium is discussed in relation to its microaerophilic nature.
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PMID:The microaerophilic respiration of Campylobacter mucosalis. 283 75

Cytochrome oxidase staining of the rat olfactory bulb external plexiform layer (EPL) produces a darkly stained intermediate zone bordered by lightly stained superficial and deep zones. Similar zonal staining was seen in cats, rabbits, and hamsters. These zones vary in relative thickness around the circumference of the olfactory bulb; the deep zone is proportionally thicker in the most dorsal and ventral parts of the bulb. Tufted cell somata are unevenly distributed within the EPL; the outer part of the EPL has more somata. The distribution of the cytochrome oxidase reaction product shows that the darkly stained intermediate zone is not produced by staining of tufted cell somata. Zones of cytochrome oxidase staining correspond to the sublaminar distribution of mitral and tufted cell basal dendrites. This was demonstrated by labeling mitral and tufted cells with small extracellular horseradish peroxidase injections and processing alternate sections for horseradish peroxidase and for cytochrome oxidase. Because there was cross-reaction of the cytochrome oxidase procedure with horseradish peroxidase, it was possible to trace many neurons through both series of sections. Middle tufted cells of the superficial EPL have basal dendrites confined to the superficial zone of light cytochrome oxidase staining. Internal tufted cells and middle tufted cells of the intermediate zone send their basal dendrites into the intermediate zone. One group of mitral cells (type I) has basal dendrites confined to the deep zone of lighter cytochrome oxidase staining. A second group of mitral cells (type II) and tufted cells of the intermediate EPL has basal dendrites primarily confined to the intermediate zone of dark cytochrome oxidase staining. The correlation of the enzyme staining with the dendritic laminar patterns supports the existence of three relatively distinct sublaminae in the EPL and supports the designation of two types of mitral cells. The staining pattern also provides an independent method for evaluating the sublaminae of the EPL without the necessity of labeling individual groups of cells. Finally, the staining pattern suggests that the intermediate zone of the EPL may be subjected to more tonic synaptic input, causing it to have an increased level of metabolic activity.
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PMID:Cytochrome oxidase staining marks dendritic zones of the rat olfactory bulb external plexiform layer. 283 32

Injections of horseradish peroxidase conjugated with wheat germ agglutinin (WGA-HRP) were made into the cortex of kittens. When cytochrome oxidase histochemistry was performed on sections taken through the injection sites staining of the WGA-HRP deposits occurred, demonstrating that WGA-HRP can cross-react during processing for cytochrome oxidase.
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PMID:Horseradish peroxidase cross-reacts during cytochrome oxidase histochemistry. 298 20

Spectral changes of hemoproteins in the near ultraviolet region on binding to a ligand and on oxidation-reduction of the heme-iron were studied by computer-controlled spectrophotometry. Near ultraviolet difference spectra between the low spin and high spin forms of ferric hemoproteins were classified into three groups: Those showing two absorption peaks having maxima at around 285 and 295 nm, those showing a peak at around 275 nm, and those showing a peak at around 300 nm. No corresponding absorption peak was observed with model heme complexes of low molecular weight. The intensity of the peak in cyanide difference spectra of catalase and horseradish peroxidase in the near ultraviolet region was dependent on the concentration of added cyanide and paralleled the intensity of the spectral changes in the Soret region. The spectral changes in both the near ultraviolet and Soret regions developed within 6 ms after the addition of cyanide. Difference spectra between the reduced and oxidized forms of cytochrome c, cytochrome oxidase-cyanide complex, hemoglobin, and lactoperoxidase-cyanide complex showed a characteristic peak at around 285-290 nm. Various difference spectra of hemoglobin in the near ultraviolet region were also measured. The observed positions, shapes, combinations, and relative intensities of the peaks were compared with those of solvent perturbation difference spectra and pH difference spectra of proteins and aromatic amino acids and also with the diacetylchitobiose-induced difference spectrum of lysozyme. The kinds of aromatic amino acid residues possibly responsible for the observed difference peaks were discussed on the basis of the results of the comparison. Based on the results obtained, the common occurrence of a heme-linked functional response of the hemoprotein conformation was suggested.
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PMID:Heme-linked spectral changes of the protein moiety of hemoproteins in the near ultraviolet region. 298 98

The reaction of H2O2 with mixed-valence and fully reduced cytochrome c oxidase was investigated by photolysis of fully reduced and mixed-valence carboxy-cytochrome c oxidase in the presence of H2O2 under anaerobic conditions. The results showed that H2O2 reacted rapidly (k = (2.5-3.1) X 10(4) M-1 X s-1) with both enzyme species. With the mixed-valence enzyme, the fully oxidised enzyme was reformed. On the time-scale of our experiments, no spectroscopically detectable intermediate was observed. This demonstrates that mixed-valence cytochrome c oxidase is able to use H2O2 as a two-electron acceptor, suggesting that cytochrome c oxidase may under suitable conditions act as a peroxidase. Upon reaction of H2O2 with the fully reduced enzyme, cytochrome a was oxidised before cytochrome a3. From this observation it was possible to estimate that the rate of electron transfer from cytochrome a to a3 is about 0.5-5 s-1.
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PMID:The oxidation of cytochrome c oxidase by hydrogen peroxide. 299 83

The postnatal development of the association projection from area 17 to area 18 was studied in normal and binocularly deprived kittens between 1 and 28 days of age, using retrograde transport of horseradish peroxidase conjugated with wheat germ agglutinin. The positions of injection sites in the visual cortex, defined in relation to the borders of visual areas 17, 18, and 19 located in Nissl- and cytochrome oxidase-stained sections, were confirmed by observing the patterns of labeling of cells in the lateral geniculate nucleus. The association projection is present and is arranged at least roughly topographically from birth onward; at all ages it arises from cells in both the superficial layers (II, III, and the upper part of IV) and the deep layers (V and VI). In older kittens (20 days or more), however, the origin of the pathway is principally from the upper layers, as in adult cats, whereas in younger animals the projection arises roughly equally from cells in superficial and deep laminae. Initially, the association neurons in area 17 are distributed uniformly along each lamina. Periodic clustering of labeled cells in the upper layers can just be discerned at 10 days, and this patchiness has reached its adult clarity by 20 days, at which stage the projection from the lower layers is greatly diminished. Binocular deprivation until the age of 28 days did not prevent these developmental changes in the projection. Various controls established that the patterns of labeling seen in this study were not due to direct spread of tracer into area 17, to uptake of tracers by fibers-of-passage, or to transcellular transport via the thalamus.
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PMID:The postnatal development of the association projection from visual cortical area 17 to area 18 in the cat. 299 44

Time-resolved resonance Raman spectroscopy is a valuable tool for the study of the dynamics of heme-protein interactions. In particular, the photolysis of a ligand by short laser pulses allows for the examination of the dynamic evolution of heme-protein interactions subsequent to ligand dissociation. To date, such studies have been confined largely to hemoglobins and myoglobins. Here we present the results of the first transient Raman study of a peroxidase. Resonance Raman spectra of horseradish peroxidase were obtained within 10 ns of ligand (CO) photolysis at a variety of pH values. We find that there is only minimal relaxation of the heme pocket of horseradish peroxidase in response to ligand photolysis. This relaxation is pH-dependent and most probably involves the heme vinyl substituents. Such behavior is in sharp contrast to the transient behavior of most hemoglobins and beef heart cytochrome oxidase.
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PMID:Transient Raman study of horseradish peroxidase. Evidence for a lack of extensive heme pocket relaxation subsequent to carbon monoxide photolysis. 299 64

Our understanding of metalloporphyrin resonance Raman spectra has advanced to the point where it is possible to obtain detailed information about the structure of the heme group in situ in heme proteins. The porphyrin skeletal mode frequencies can be analyzed in terms of the ligation and spin state of the heme and may provide information about protein-induced stresses. The high-frequency region of the spectrum also contains bands due to vibrations of the porphyrin peripheral substituents, which are potentially monitors of the protein contacts. In the low-frequency region, it is possible to locate bands, at least in some states of the heme protein, which are associated with vibrations of the axial ligands. They give direct information about the nature of the bonding to exogenous ligands or to the proximal protein residue. Thus, a variety of evidence is potentially available in the resonance Raman spectra from which a fairly complete picture of the heme site can be assembled for a particular protein in its various functional states. Detailed studies have been pursued for paradigmatic heme proteins, including myoglobin, hemoglobin, cytochrome c, horseradish peroxidase, and cytochrome oxidase. These studies provide a substantial data base from which the exploration of lesser known systems can be launched. Another extension of current knowledge to new frontiers is in the time domain, since pulsed lasers now make it feasible to carry out time-resolved resonance Raman studies on heme protein reactions. Time-resolved resonance Raman spectroscopy is capable of elucidating the temporal evolution of heme structure and provides a link between heme chemistry and protein dynamics. This link is being elucidated for hemoglobin and cytochrome c, where specific heme intermediates have been identified following ligand photodissociation or electron transfer.
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PMID:Resonance Raman spectroscopy as a probe of heme protein structure and dynamics. 299 61

Coupled with the peroxidatic oxidation of ferrocytochrome c under anaerobic conditions, proteoliposomes reconstituted with a purified preparation of bovine heart cytochrome oxidase ejected protons into the external medium with an apparent H+/e- ratio of 0.9. At the same time, protons in the intravesicular space were consumed. Dicyclohexylcarbodiimide significantly inhibited the proton translocation. Cyanide (0.14 mM) completely inhibited both the peroxidase and proton translocating activities. On the contrary, in the presence of 1 mM CO the proton ejection was abolished almost completely, but 50% of the peroxidase activity persisted. This result suggests the operation of multiple mechanisms in the peroxidase reaction and that the CO-sensitive one is coupled to the proton translocation.
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PMID:Proton translocation by cytochrome oxidase vesicles catalyzing the peroxidatic oxidation of ferrocytochrome c. 300 9

P beta (color opponent) retinal ganglion cells in macaques were found to degenerate as a result of oral administration of acrylamide. Histological examination, wheat germ agglutinin-horseradish peroxidase transport and cytochrome oxidase histochemistry indicate that other retinal ganglion cells and other neurons in the visual pathways were spared.
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PMID:Selective acrylamide-induced degeneration of color opponent ganglion cells in macaques. 301 58


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