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)

In 175 dogs myocardial infarction was produced by high ligation of descending branch of left coronary artery. At various intervals after the intervention (1, 3, 5, 10, 30, 180 days), the activities and levels of NAD, NADH, FAD, riboflavin, cytochrome C, myoglobin, some NAD-dependent Krebs cycle enzymes, and mitochondrial succinate dehydrogenase and cytochrome oxidase were determined in the infarcted zone. It was found that in the infarcted zone there occurred substantial disturbances of various links constituting the tissue oxidative chain, in the stages of substrate dehydrogenation, electron transport to oxygen molecule, and myocardial oxygen uptake. The greatest disturbances took place in the systems of NAD and NAD-dependent enzymes, whereas the succinate oxidation system sustained substantially lesser damage. The decrease inlevels of flavonoids, which was likewise observed, participated also in the mechanism inhibiting succinate dehydrogenase. The cytochrome system activity was limited by the level of cytochrome C, whose deep decrease persisted considerably long in the infarcted zone. A certain role in disturbances of oxidative processes may have been played by the decreased concentration of myoglobin, an important myocardial reservoir of oxygen.
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PMID:Some myocardial factors of biological oxidation in experimental myocardial infarction. 19 79

The optical characteristics of the hemoglobin-free perfused rat heart have been examined in detail. For dual-wavelength spectrophotometry, absorption pairs at 605-620 nm and 587-620 nm are found to be suited for the investigation of the oxidation-reduction changes of cytochrome aa3 and oxygenation-deoxygenation of myoglobin in cardiac tissue. Techniques by which the absorption changes of myoglobin and cytochrome aa3 can be measured during one cycle of contraction-relaxation are presented. The results demonstrate that, in the aerobic state, myoglobin is more oxygenated during the systolic and diastolic periods and deoxygenated in the resting period, whereas cytochrome aa3 is more reduced in the systole and diastole and oxidized in the resting period.
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PMID:A new spectroscopic approach to cardiac energy metabolism. 103 30

Infrared difference spectra, FeIIICO vs. FeIII of horseradish peroxidase isoenzymes A2 and C were recorded from 2000 to 1800 cm-1. Under alkaline conditions, pH 9, both isoenzymes exhibit two CO stretching bands, at 1938 and 1925 cm-1 for A2 and at 1933 and 1929 cm-1 for C. As the pH is lowered the low-frequency band for each isoenzyme decreases in intensity with a concommitant appearance and increase in intensity of a band at 1906 and 1905 cm-1 for the A2 and C isoenzymes, respectively. These changes conform to pK values of 6.7 for the A2 and 8.8 for the C isoenzymes of horseradish peroxidase. The interpretation of the infrared results was simplified by the observation that a linear relationship exists between the redox potential, Em7, for the FeIII/FeII system vs. the infrared CO stretching frequency, vCO, for cytochrome a3, hemoglobin, myoglobin, and cytochrome P-450 cam with substrate. This relationship suggests that the primary force altering vCO in these heme proteins is a variation in electron density at the heme iron and not direct protein interactions with the CO ligand. The horseradish peroxidase infrared bands in the 1930-cm-1 region correlate well with this relationship. The large deviation of the 1905-cm-1 band from the linear relationship and its dependence upon hydrogen ion concentration are consistent with horseradish peroxidase having a single CO binding site which can hold in two geometries, one of which contains an amino acid moiety capable of forming a hydrogen bond to the carbonyl oxygen.
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PMID:Infrared spectroscopic studies of carbonyl horseradish peroxidases. 127 34

Iron, apart a for long time well-known function connected with: transportation (hemoglobin), storage (myoglobin), and utilize (cytochromes, cytochrome oxidase) oxygen for respiration, has a critical role in host-pathogen interactions. Iron is essential for microbial growth, but also for immune function. The role of iron in infection, thermoregulation, acute lymphocytic leukemia, neoplasia, rheumatoid arthritis, stimulation of free radical reactions, and studies with iron chelation therapy are discussed.
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PMID:[The role of iron in immunologic processes]. 129 87

Ground state near-infrared absorption spectra of fully reduced unliganded and fully reduced CO (a2+ CuA+ a3(2+)-CO CuB+) cytochrome c oxidase were investigated. Flash-photolysis time-resolved absorption difference spectra of the mixed-valence (a3+ CuA2+ a3(2+)-CO CuB+) and the fully reduced CO complexes were also studied. A band near 785 nm (epsilon approximately 50 M-1cm-1) was observed in the fully reduced unliganded enzyme and the CO photoproducts. The time-resolved 785 nm band disappeared on the same timescale (t1/2 approximately 7 ms) as CO recombined with cytochrome a3(2+). This band, which is attributed to the unliganded five coordinate ferrous cytochrome a3(2+), has some characteristics of band III in deoxy-hemoglobin and deoxy-myoglobin. A second band was observed at approximately 710 nm (epsilon approximately 80 M-1cm-1) in the fully reduced unliganded and the fully reduced CO complexes. This band, which we assign to the low spin ferrous cytochrome a, appears to be affected by the ligation state at the cytochrome a3(2+) site.
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PMID:Evidence for a band III analogue in the near-infrared absorption spectra of cytochrome c oxidase. 131 22

The cellular oxygen supply in the isolated, hemoglobin-free perfused, working rat heart can be determined by measurements of myoglobin oxygenation. However, for a precise analysis of mitochondrial hypoxia and anoxia (pO2 < 0.01 Torr) redox-state of respiratory enzymes must be known. By use of the EMPHO (Frank et al. 1989) it is possible to perform a high speed spectrometry within very small tissue volumes. Because of the characteristic absorption spectra of oxygenated and deoxygenated myoglobin and of the oxidized and reduced cytochrome aa3 within the wavelength interval from 500 to 630 nm it is possible to isolate these two pigments from the remission spectra and to determine the oxygenation state of myoglobin and the redox-state of cytochrom aa3.
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PMID:Monitoring of redox-state of respiratory enzymes and myoglobin oxygenation in the working rat heart in normoxia and oxygen deficiency. 133 58

Myocardial O2 consumption (MVO2) was stimulated up to two-fold by either increasing afterload or beta-receptor stimulation in working normothermic isolated rabbit hearts while noninvasively monitoring the O2 delivery or phosphate compounds (total n = 48). Intracellular O2 delivery was estimated with the use of myocardial optical absorbance changes centered at 603.5 and 582 nm that correlate with cytochrome aa3 redox and myoglobin oxygenation states. Phosphate-containing metabolites (ATP, phosphocreatine, free ADP) were assessed using 31P nuclear magnetic resonance spectroscopy. Measurements were made both with intact autoregulation and after maximal vasodilation by 1 microM nitroprusside (NP). When afterload was used to increase MVO2, absorbance decreased at 603.5 nm and increased at 582 nm, consistent with a 10-15% increase in myocardial oxygenation, without an associated change in cardiac phosphate compounds. NP caused a further increase in myocardial oxygenation and venous PO2 consistent with an increase in the O2 supply-to-demand ratio. Increases in MVO2 due to beta-stimulation alone were not associated with changes in 603.5-nm absorbance or phosphate compounds, but in combination with NP were accompanied by increased oxygenation, venous PO2, and cardiac phosphocreatine. KCl arrest caused maximal increases in oxygenation and phosphocreatine. These findings suggest that neither cytochrome aa3 nor myoglobin in the isolated working rabbit heart is fully oxidized or oxygenated, respectively. Furthermore, the oxygenation state of the tissue varied both with afterload-induced changes in cardiac work and with changes in O2 supply/demand.
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PMID:Myocardial oxygenation in the isolated working rabbit heart as a function of work. 134 58

The effects of temperature on oxygenation and metabolism in perfused rat hindlimb was studied at 35 degrees C and 15 degrees C. Oxygenation of myoglobin and oxidation of cytochrome aa3 in the thigh (quadriceps) muscle were estimated from the difference spectra measured with a rapid-scanning spectrophotometer. Simultaneously, oxygen uptake and release of lactate and pyruvate were measured. (1) In hypothermia, glycolysis played a major role in energy metabolism even though Cyt aa3 was maintained in a more oxidized state than in normothermia. (2) P50 of myoglobin in perfused rat hindlimb was 5.0 mmHg at 35 degrees C, 2.3 mmHg at 25 degrees C and 1.1 mmHg at 15 degrees C. The delta H degree was -13.0 kcal/mol. (3) When about 30% of myoglobin was deoxygenated at both 35 degrees C and 15 degrees C, the oxygen uptake started to decrease and lactate release increased. (4) At 35 degrees C, the oxidation level of cytochrome aa3 was same as the oxygenation level of myoglobin. At 15 degrees C, however, the oxidation level of cytochrome aa3 was clearly higher than the oxygenation level of myoglobin. The oxygen uptake at 15 degrees C was about one third that at 35 degrees C. In conclusion, in order to maintain the aerobic condition of cytochrome aa3 in mitochondria of rat skeletal muscle, a tissue oxygen tension higher than 12 mmHg at 35 degrees C, and higher than 3 mmHg at 15 degrees C is required.
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PMID:Temperature effect on oxygenation and metabolism of perfused rat hindlimb muscle. 196 61

Myocardial oxygenation may be altered markedly by changes in tissue blood flow. During brief ischemia and reperfusion produced by transient occlusion of the left anterior descending artery in 10 open-chest dogs, changes in the oxygenation of tissue hemoglobin (Hb) plus myoglobin (Mb) and the oxidation-reduction (redox) state of mitochondrial cytochrome aa3 were monitored continuously using near-infrared spectroscopy. The nondestructive optical technique indicated that coronary occlusion produced an abrupt drop in tissue oxygen stores (tHb02 + Mb02), tissue blood volume (tBV), and the oxidation level of cytochrome aa3. Changes in the cytochrome oxidation state were related inversely to transmural collateral blood flow within the ischemic region (r = 0.77) measured with radiolabeled microspheres. Furthermore, there was a direct relationship (r = 0.91) between collateral blood flow and the tissue level of desaturated Hb and Mb (tHb + Mb). Reperfusion after 2 min of ischemia led to a synchronous overshoot of baseline in coronary flow and tBV followed by supranormal increases in tHb + Mb02 and the oxidation level of cytochrome aa3. The tHb + Mb level increased transiently during reperfusion. This response correlated inversely with collateral flow during ischemia (r = 0.91). Accordingly, the time required to reach peak tHb + Mb levels was shortest in dogs with high collateral flows (r = 0.75). Thus collateral blood flow partially sustains myocardial oxygenation during coronary artery occlusion and influences tissue reoxygenation early during reperfusion.
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PMID:Dynamic mechanisms of cardiac oxygenation during brief ischemia and reperfusion. 217 24

Clinical data suggest, and experimental studies indicate direct cardiotoxic effects of carbon monoxide, apart from carboxyhemoglobin formation. Carbon monoxide interactions with cytochrome oxidase and myoglobin are suspect. Of these, myoglobin is the favored tissue target for carbon monoxide binding. On what evidence? Examination of the literature reveals the following: A 16% greater "volume of distribution" (Vd) for carbon monoxide, versus other blood volume indicators, concentrating in skeletal and cardiac muscle; A high myoglobin content in these tissues corresponding to this "excess" Vd for carbon monoxide; Evidence from animals of significant carboxymyoglobin concentrations; Hemeprotein independent changes produced by carbon monoxide which promote carbon monoxide-myoglobin interactions; A high ratio of deoxymyoglobin (carbon monoxide binding form) to oxymyoglobin intracellularly; Direct intercellular measurements of oxymyoglobin saturations and "cycling" in vivo illustrating favorable conditions for carbon monoxide binding; Data indicating decrements in cardiac performance with loss of functional myoglobin; Evidence that myoglobin is important to the proper functioning of cardio-adaptive mechanisms in stress. The total picture of carbon monoxide poisoning must take into account pathogenic effects due to carboxymyoglobin formation.
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PMID:A review of carboxymyoglobin formation: a major mechanism of carbon monoxide toxicity. 223 44


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