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At least 19 recordsLinked to original sources
PubMed1984

Formation and decay of the primary oxygen compound of cytochrome oxidase at room temperature as observed by stopped flow, laser flash photolysis and rapid scanning.

Rapid kinetic and scanning techniques were employed to observe the reaction of dioxygen with fully reduced cytochrome oxidase at room temperature following stopped flow flash photolysis of the CO compound of the enzyme. The initial product of the reaction was an oxygen compound with a spectral profile quite similar to that of the cytochrome oxidase-CO compound. The second order rate constant for formation of the primary oxygen compound was 1.1 X 10(8) M-1 S-1 at pH 7.4 and 25 degrees C. With an off rate constant of 1.9 X 10(3) S-1, the calculated dissociation constant was 1.8 X 10(-5) M. The apparent activation energy was 16.7 kJ/mol. The primary oxygen compound underwent further reaction which was independent of oxygen concentration with a rate constant of 1.2 X 10(3) S-1, and the product was Intermediate III ( Orii , Y. (1982) in Oxygenases and Oxygen Metabolism ( Nozaki , M., Yamamoto, S., Ishimura , Y., Coon , M. J., Ernster , L., and Estabrook , R., eds) pp. 137-149, Academic Press, New York), an oxidized species presumably identical to the "oxygen pulsed" oxidase. Thus, this reaction was ascribed to intramolecular electron transfer to the oxygen in the compound. The energy of activation was 49.8 kJ/mol below 18 degrees C but above that the rate constant was independent of temperature, and a "tunneling" mechanism was suggested for the intramolecular electron transfer.

Animals↗
PubMed1991

[Generation of active oxygen compounds by whole blood granulocytes in patients with chronic renal failure].

In patients with chronic renal failure (crf) on conservative treatment whole blood granulocyte superoxide anion (O2-) generation was significantly decreased. Regular hemodialysis treatment did not induce its significant improvement. As granulocyte O2- generation determines production of other active oxygen compounds, this phenomenon may lead to the impairment of phagocyte bactericidal activity and increased susceptibility to infections in crf. Various methods of determination of active oxygen compounds give incomparable results.

Adolescent↗
PubMedDate not supplied

Identification of oxygenated compounds in combustion systems.

An attempt for the spectroscopic identification of oxygenated compounds produced in combustion processes under different environmental conditions is reported in this paper. A deeper knowledge about presence and evolution of such species in dependence of the operating conditions of practical burner represents a fundamental hint to the objective of an advancement of the control of combustion process and reduction of pollutant emissions. This paper mainly focuses on species characterized by the presence of carbonyl functionality since aldehydes, ketones and diketones are among the principal intermediate species and products of hydrocarbon oxidation. They are by themselves to be considered atmospheric pollutants and are also indicators of actual pathways followed during the chemical reactions occurring in the combustion process. For these reasons they are most suitable for the exploitation of the above indicated objectives. In this paper, a classification of spectroscopic features and markers of these classes of carbonyl compounds is presented on the basis of both literature and spectra collected from sample species. This interpretative scheme is then used for the attribution of fluorescence signals collected from a tetradecane spray in different environmental conditions.

Journal Article↗
PubMed2000

Trace analysis of ethanol, MTBE, and related oxygenate compounds in water using solid-phase microextraction and gas chromatography/mass spectrometry.

Solid-phase microextraction (SPME) and gas chromatography/mass spectrometry have been combined for trace-level determination of very polar compounds in water, including the widely used gasoline oxygenates ethanol and methyl tert-butyl ether (MTBE). A relatively simple extraction method using a divinylbenzene/Carboxen/poly(dimethylsiloxane) SPME fiber was optimized for the routine analysis of ethanol and MTBE in groundwater and reagent water. A sodium chloride concentration of 25% (w/w) combined with an extraction time of 25 min provided the greatest sensitivity while maintaining analytical efficiency. Replicate analyses in fortified reagent and groundwater spiked with microgram per liter concentrations of ethanol and MTBE indicate quantitative and reproducible recovery of these and related oxygenate compounds. Method detection limits were 15 microg L(-1) for ethanol, 1.8 microg L(-1) for tert-butyl alcohol, 0.038 microg L(-1) for tert-amyl methyl ether, 0.025 microg L(-1) for ethyl-tert-butyl ether, and 0.008 microg L(-1) for MTBE.

Ethanol↗
PubMed1981

Diminished osmotic fragility of human erythrocytes following the membrane insertion of oxygenated sterol compounds.

Oxygenated sterol compounds (OSC), when incubated for 1 hr with human erythrocytes in lipoprotein-depleted medium at concentrations of 0.625-5 X 10(-5) M, are inserted into the cell membrane and remain there despite subsequent washing of the cells. The insertion results in expansion of the surface area of the red cell ghost membrane, an increase in critical hemolytic volume, and as a consequence, in diminished osmotic fragility of the erythrocytes. This effect is seen with echinocyte-forming as well as with non-echinocyte-forming OSC. Erythrocytes treated with OSC do not differ from control cells with respect to their mean cell volume (MCV) in isotonic solution, water content, ion fluxes, and filterability through polycarbonate filters. The shift of the osmotic fragility curve toward lower NaCl concentrations is proportional to the amount of OSC inserted into the red cell membrane. 7 beta-Hydroxycholesterol, 22-ketocholesterol, and 20 alpha-hydroxycholesterol are the most potent inhibitors of osmotic lysis. The effect of OSC on osmotic fragility is diminished if the erythrocytes are incubated in a lipoprotein-containing medium; free cholesterol, however, does not change this effect. Various progesterones also protect red cell from osmotic lysis, but only if the erythrocytes are directly exposed to the compounds present in the hypotonic NaCl solutions used for measurement of their osmotic fragility. Progesterones do not remain in the membrane after the cells have been washed. The OSC are also capable of correcting the osmotic fragility curve of red cells from patients with hereditary spherocytosis. These experiments may suggest an approach to the pharmacologic treatment of hereditary spherocytosis.

Cell Membrane↗
PubMed1978

Adriamycin and daunomycin generate reactive oxygen compounds in erythrocytes.

Adriamycin and daunomycin produce dose-related cardiac toxicity that may be related to oxygen radicals. Addition of these compounds to human erythrocyte suspensions resulted in stimulation of hexose monophosphate shunt activity that was markedly impaired in the absence of oxyhemoglobin. Evidence for generation of hydrogen peroxide by these compounds was provided by oxidation of reduced glutathione, by 14C-formate oxidation, and by the catalase-aminotriazole trapping technique. These experiments indicate that Adriamycin and daunomycin interact with oxyhemoglobin to generate reactive oxygen metabolites. A similar interaction with oxymyoglobin may occur in the heart and produce oxygen radicals that injure cardiac myocytes.

Daunorubicin↗
PubMed1988

Oxygenated compounds in beeswax: identification and possible significance.

1. Beeswax synthesized by non-foraging honeybee workers contains six oxygenated volatiles in addition to a series of normal alkanes. 2. Decanal constitutes nearly 50% of the oxygenated volatiles and is accompanied by octanal, nonanal, furfural, benzaldehyde and 1-decanol. 3. The possible significance of the aldehydes as stimulators of hoarding behaviour and attractants for wax moths is discussed.

Aldehydes↗
PubMed1983

The 650 and chromophore in Escherichia coli is an 'oxy-' or oxygenated compound, not the oxidized form of cytochrome oxidase d: an hypothesis.

The form of cytochrome d in Escherichia coli and Azotobacter vinelandii that shows an absorption maximum at 648 to 652 nm ('cytochrome d650') is generally regarded as the oxidized form of this terminal oxidase. Membranes from E. coli grown under oxygen-limited conditions, when treated with ferricyanide, do not reveal cytochrome d650, whereas a sharp symmetrical band at 652 nm results from the reaction of the reduced enzyme with O2 at either room temperature or after flash photolysis of the CO-liganded form at -130 degrees C. Electron paramagnetic resonance spectroscopy of cytochrome d650 trapped at -130 degrees C shows that its spectrum is indistinguishable from the CO-liganded form and does not reveal resonances of high spin ferric haem previously attributed to cytochrome d. An hypothesis is proposed in which cytochrome d650 is an early intermediate in the reaction of reduced cytochrome d650 and oxyhaemoglobin is presented and the hypothesis discussed in relation to earlier work, in which the indirect interconversions of reduced cytochrome d and d650 have been explained by proposing the existence of an 'invisible' form. It is suggested that this form could be the oxidized enzyme.

Cytochrome d Group↗
PubMed2000

A density-functional theory based study on the 16O/18O-exchange reactions of the prototype iron-oxygen compounds FeO+ and FeOH+ with H2(18)O in the gas phase

The mechanism of the degenerate 16O/18O exchange in the reactions of FeO+ and FeOH+ with water is examined by density functional theory. Based on previous experimental work (Chem. Eur. J. 1999, 5, 1176), two possible reaction pathways are investigated for both systems. The first mechanism consists of one (for FeOH+ + H20) or two (for FeO+ + H20) 1,3-hydrogen migrations from one oxygen atom to the other; the iron atom is not directly involved in these OH bond activations. The second route comprises a series of two (for FeOH+ + H20) or four (for FeO+ + H20) 1,2-hydrogen migration steps which involve the intermediate formations of metal-hydrogen bonds. Both mechanisms are evaluated under consideration of the respective low- and high spin potential-energy surfaces. The computational results show a clear preference for the 1,3-routes occurring on the respective high-spin surfaces bypassing the intermediacy of high-valent iron compounds having FeH bonds.

Journal Article↗
PubMed1993

Characterization of trace amounts of odorants (sulfur compounds, oxygenates, hydrocarbons, phenols and lower fatty acids) in air in an ICU room.

Characterization of trace amounts of odorants in air in an ICU room (ca.257m2) was carried out by gas chromatography and atmospheric pressure ionization-mass spectrometry (API-MS). The concentrations and odor recognition threshold values of the detected odorants, acetaldehyde, ethanol, n-butyric acid, iso-valeric acid and n-valeric acid are as follows: 44.7 ppb and 15 ppb; 19710 ppb and 6100 ppb; 0.50 ppb and 0.4 ppb; 0.45 ppb and 0.4 ppb; 0.67 ppb and 0.5 ppb, respectively. The detected concentrations of these odorants were significantly higher than the odor recognition threshold values. The compounds may, therefore, be responsible for perception of such odors as mixed odors, body odor, and faint or recognizable alcoholic odor, disinfectant odor, and sour, pungent, and goat odors.

Chromatography, Gas↗
PubMed1985

The role of reactive oxygen compounds derived from 6-hydroxydopamine for bone marrow purging from neuroblastoma cells.

6-Hydroxydopamine(6-OHDA), a specific neurotoxin against sympathetic nerve cells, is a drug already used for purging of bone marrow from neuroblastoma cells before autologous bone marrow transplantation. However, we could not detect significant differences in the toxicity of 6-OHDA against neuroblastoma and other tumor cells under the purging conditions clinically used. In contrast, bone marrow stem cells were much more resistant. The unspecific toxic effect of 6-OHDA is caused by H2O2 or H2O2-derived products which are generated by auto-oxidation in the incubation medium before a significant amount of 6-OHDA is taken up by the cells. Withdrawal of oxygen during the incubation period and subsequent incubation with an oxygen containing medium led to a more specific destruction of neuroblastoma cells which can take up 6-OHDA selectively.

Ascorbic Acid↗
PubMed1999

Abiotic formation of hydrocarbons and oxygenated compounds during thermal decomposition of iron oxalate.

The formation of organic compounds during the decomposition of iron oxalate dihydrate (IOD) was investigated as a possible analog for abiotic organic synthesis in geological systems. After heating at 330 degrees C for 2-4 days, IOD decomposed to a mixture of the minerals siderite and magnetite plus gas and non-volatile organic compounds. The organic products included an extremely large variety of compounds, making identification of individual reaction products difficult. However, the non-volatile products were dominated by several homologous series of alkylated cyclic compounds mostly containing a single aromatic ring, including alkylphenols, alkylbenzenes, alkyltetrahydronaphthols, and alkyltetrahydronaphthalenes. Traces of n-alkanols, n-alkanoic acids, n-alkanones, and n-alkanes were also identified. Carbon in the gas phase was predominantly CO2 (+CO?), with lesser amounts of light hydrocarbons to > C6 including all possible branched and normal isomers of the alkanes and alkenes. The organic products were apparently the result of two concurrent reaction processes: (1) condensation of the two-carbon units present in the initial oxalate moiety, and (2) Fischer-Tropsch-type synthesis from CO2 or CO generated during the experiment. Compounds produced by the former process may not be characteristic of synthesis from the single-carbon precursors which predominate in geologic systems, suggesting iron oxalate decomposition may not provide a particularly suitable analog for investigation of abiotic organic synthesis. When water was included in the reaction vessels, CO2 and traces of methane and light hydrocarbon gases were the only carbon products observed (other than siderite), suggesting that the presence of water allowed the system to proceed rapidly towards equilibrium and precluded the formation of metastable organic intermediates.

Ferrosoferric Oxide↗