Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The energy relationships between cytosolic and mitochondrial metabolism were studied in the hearts from euthyroid, hypothyroid, and hyperthyroid rats. Isolated mitochondria showed high respiratory control ratios and impermeability to exogenous NADH. Hypo- and hyperthyroidism, respectively, resulted in lower and higher contents of both cytochromes per mitochondrion and mitochondrial protein per gram of wet weight of heart without changes in the ratio of cytochrome c to cytochrome aa3. In isolated perfused heart, the hyperthyroid state led to an increase in work rate and thereby an elevation of Vo2, which resulted in an increase oxidation-reduction turnover number for the cytochromes. An agreement was found between [ATP]/[ADP][Pi] of cytosolic free adenine nucleotides and the value calculated from a mathematical model of mitochondrial respiration. This implies that mitochondrial respiration is controlled at the cytochrome oxidase reaction and that oxidative phosphorylation in intact tissue is tightly coupled irrespective of thyroid state. It is concluded that thyroid hormone causes an increase in the mitochondrial mass, mitochondrial cytochrome content, and respiratory rate, and consequently expands the capacity of oxidative metabolism without an uncoupling effect on oxidative phosphorylation.
 ...
PMID:Evaluation of oxidative phosphorylation in hearts from euthyroid, hypothyroid, and hyperthyroid rats. 21 35

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.
 ...
PMID:Clinical features and management of cyanide poisoning. 353 Jun 15

Thiosulphate is one of the products of the initial step of the elemental sulphur oxidation pathway in the thermoacidophilic archaeon Acidianus ambivalens. A novel thiosulphate:quinone oxidoreductase (TQO) activity was found in the membrane extracts of aerobically grown cells of this organism. The enzyme was purified 21-fold from the solubilized membrane fraction. The TQO oxidized thiosulphate with tetrathionate as product and ferricyanide or decyl ubiquinone (DQ) as electron acceptors. The maximum specific activity with ferricyanide was 73.4 U (mg protein)(-1) at 92 degrees C and pH 6, with DQ it was 397 mU (mg protein)(-1) at 80 degrees C. The Km values were 2.6 mM for thiosulphate (k(cat) = 167 s(-1)), 3.4 mM for ferricyanide and 5.87 micro M for DQ. The enzymic activity was inhibited by sulphite (Ki = 5 micro M), metabisulphite, dithionite and TritonX-100, but not by sulphate or tetrathionate. A mixture of caldariella quinone, sulfolobus quinone and menaquinone was non-covalently bound to the protein. No other cofactors were detected. Oxygen consumption was measured in membrane fractions upon thiosulphate addition, thus linking thiosulphate oxidation to dioxygen reduction, in what constitutes a novel activity among Archaea. The holoenzyme was composed of two subunits of apparent molecular masses of 28 and 16 kDa. The larger subunit appeared to be glycosylated and was identical to DoxA, and the smaller was identical to DoxD. Both subunits had been described previously as a part of the terminal quinol:oxygen oxidoreductase complex (cytochrome aa3).
 ...
PMID:Coupling of the pathway of sulphur oxidation to dioxygen reduction: characterization of a novel membrane-bound thiosulphate:quinone oxidoreductase. 1530 18