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)

An improved procedure for the preparation of cobalt-cytochrome c has been developed. Various factors influencing the cobalt insertion process are discussed. The optical spectra of cobalt-cytochrome c suggest a six-coordinated species. The spectral shifts occurring with oxidation-reduction are compared with those observed for deoxy-cobaltohemoglobin and ferrocytochrome c and attributed to the effect of d(z2) electron on stereoelectronic interactions between the axial ligands and the porphyrin pi systems. Cobalt-cytochrome c has Em,7 = -140 +/- 20 mV as compared to an Em,7 of +250mV for ferrocytochrome c. An explanation for this negative Em,7 is offered. Cobaltocytochrome c is oxidized by cytochrome oxidase at about 45% of the rate for native cytochrome c. On the other hand cobalticytochrome c was not reduced by microsomal NADH or NADPH cytochrome c reductase nor by mitochondrial NADH or succinate cytochrome c reductase. It appears that the integrity of the reductase binding site is destroyed and the oxidase binding site has been modified by cobalt substitution.
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PMID:Cobalt-cytochrome c. I. Preparation, properties, and enzymic activity. 16 80

The pathophysiology, clinical features, and management of cyanide toxicity are reviewed and sources of cyanide are listed. Cyanide is a deadly poison that is found in many foods and household and industrial products, including some that are readily available. Cyanide binds with cytochrome oxidase, the enzyme responsible for oxidative phosphorylation, and paralyzes cellular respiration. Because the tissues cannot use oxygen that is delivered, aerobic metabolism ceases. The signs and symptoms of cyanide poisoning reflect the extent of cellular hypoxia. Manifestations may include respiratory abnormalities (progressing from tachypnea and dyspnea to respiratory depression and apnea), hemodynamic instability, metabolic acidosis, and, possibly, local irritant effects after oral ingestion of cyanide. The mainstays of therapy are 100% oxygen and specific antidotes to cyanide. Sequential treatment with amyl nitrite by inhalation, intravenous sodium nitrite 3%, and intravenous sodium thiosulfate 25% is directed toward decreasing the amount of cyanide available for cellular binding. Nitrites convert hemoglobin to methemoglobin, which reacts with cyanide to form cyanomethemoglobin. Sodium thiosulfate serves as a source of sulfur groups, which are needed for conversion of cyanide to thiocyanate, a compound that is relatively less toxic and is excreted renally. Supportive care also is important. Cobalt EDTA, hydroxocobalamin, and aminophenols have also been used but are not considered standard treatments. Cyanide poisoning is a medical emergency that requires prompt recognition and immediate and aggressive treatment.
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PMID:Clinical features and management of cyanide poisoning. 353 Jun 15

Cobalt and desferrioxamine, like hypoxia, stimulate the production of erythropoietin in HepG2 cells. It is believed that cobalt as well as desferrioxamine interact with the central iron atom of heme proteins by changing their redox state similar to hypoxia. A subsequent decrease of the intracellular H2O2 levels under hypoxia was presumed to be the key event for stimulating erythropoietin production. We therefore investigated whether cobalt and desferrioxamine control the intracellular H2O2 levels that regulate gene expression by interacting with hemeproteins. Deconvolution of light absorption spectra revealed respiratory heme proteins such as cytochrome c, b558 and cytochrome aa3, as well as cytochrome b558, which is a nonrespiratory heme protein found in HepG2 cells. Whereas respiratory heme proteins are located in mitochondria, cytochrome b558 similar to the one described for the neutrophil NADPH oxidase can be visualized in the cell membrane of HepG2 cells by immunohistochemistry. Incubation with cobalt (100 microM/24 hr) interacts predominantly with cytochrome b558 and cytochrome b558. The interaction of cobalt with the respiratory chain results in an increased oxygen consumption of HepG2 cells as revealed by PO2 microelectrode measurements. Desferrioxamine (130 microM/24 hr), however has no influence on the cytochromes. In response to an external application of NADH (1 mM), the membrane bound cytochrome b558 produces two times more O2- than to the external NADPH (1 mM) application. Neither desferrioxamine not cobalt has any influence on the NADH stimulated O2- generation. Incubation with cobalt or with desferrioxamine, however, leads to a decrease of the intracellular H2O2 level as revealed by the dihydrorhodamine 123 technique, perhaps causing the well-known enhanced erythropoietin production. The cobalt-induced H2O2 decrease seems to be caused by an increased activity of the glutathion peroxidase that is also induced under hypoxia. Desferrioxamine, however, leads to an apparent H2O2 decrease only because it seems to inhibit the iron catalyzed reaction of H2O2 with dihydrorhodamine 123, hinting at the occurrence of the Fenton reaction in HepG2 cells. Therefore, it must be determined whether or not degradation products of H2O2 by the Fenton reaction suppress erythropoietin production under normoxia.
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PMID:Cobalt and desferrioxamine reveal crucial members of the oxygen sensing pathway in HepG2 cells. 902 27

This study was conducted to investigate the physiological consequences of long-term moderate cobalt deficiency in beef cattle, which have not hitherto been studied in detail. Cobalt deficiency was induced in cattle by feeding two groups of animals either a basal corn silage-based diet that was moderately low in cobalt (83 micrograms Co/kg), or the same diet supplemented with cobalt to a total of 200 micrograms per kg, for 43 weeks. Cobalt deficiency was induced, as judged by inappetance, diminished growth gain and a markedly reduced vitamin B12 status in serum and liver. The long-term cobalt deprivation which was primarily a combination of reduced feed intake and a tissue vitamin B12 deficiency did not show evidence of a significant dysfunction of energy metabolism. The activities of glucose-6-phosphate dehydrogenase and cytochrome oxidase in liver remained unaffected by cobalt deficiency, nor was there a significant change in serum glucose level of cattle on the cobalt-deprived diet. However, analysis of thyroid hormone status indicated a slight reduction of type I thyroxine monodeiodinase activity in liver accompanied by a significant reduction of the triiodothyronine level in serum. The diminished liver vitamin B12 level resulted in significantly reduced folate level in this tissue, reduced concentrations of heme-depending blood parameters. Moreover cobalt deficiency or rather vitamin B12 deficiency was accompanied by a dramatic accumulation of the trace elements iron and nickel in liver. These results indicate that long-term moderate cobalt deficiency may induce a number of physiological changes in cattle, but a follow-up study, which excluded different feed levels by including a pair-fed control group, will be necessary to actually obtain the single effect of cobalt deficiency in cattle.
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PMID:Cobalt deficiency effects on trace elements, hormones and enzymes involved in energy metabolism of cattle. 1021 49