Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: CAS:7782-44-7 (oxygen)
 369,292 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It has been shown that the action of ionizing radiations on dilute, oxygen-free, aqueous solutions of acetonitrile and propionitrile leads to the formation of oligomers, which upon hydrolyses release amino acids. The presence of nine amino acids, the same as those found in irradiated aqueous cyanides, has been established. those amino acids with asymmetric carbon atoms separated by GC method, appeared to consist of nearly equal amounts of D and L isomers. Glycine is the most abundant amino acid in hydrolysates of acetonitrile, while alanine appears in the samples of propionitrile. A comparison of all amino acids, identified in hydrolysates of various cyanides and nitriles, suggests that it is the cyano group, and a free-radical initiated mechanism, that is primarily involved in these radiation-chemical changes of potential interest to prebiotic chemistry.
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PMID:Evidence of amino acids in hydrolysates of compounds formed by ionizing radiations. II. Aqueous solutions of CH3CN and C2H5CN. 61 30

Thermal and binary cosolvent studies of the cholesterol oxidase (cholesterol: oxygen oxidoreductase, EC 1.1.3.6) reaction have been carried out using batch microcalorimetry and ultraviolet spectrophotometry respectively. Heat conduction measurements are shown to provide the basis for a serum cholesterol assay yielding results comparable to conventional automated clinical assay. The enthalpy of the reaction for cholesterol oxidation, measured with different sources of the enzyme in the presence and absence of catalase is -113 +/- 7.2 mJ/mumol. The value is agreement with calculated estimates based on bond energies, enthalpies of formation and trigonal additivity contribution calculations. From this heat of reaction the deltaHf0 of cholestenone (c) is calculated to be -490 kJ . mol-1. No evidence for the reverse reaction could be adduced. Enzyme activation with detergent (Surfal) is attributed to the formation of mixed micelles of cholesterol with detergent molecules. The detergent concentration at which the enzyme is half activated corresponds to the critical micelle concentration of Surfal. The enhanced enzyme activity found when ethanol, acetonitrile and dioxane were examined as binary cosolvents with water is ascribed to a conformational change in the enzyme mediated through the altered structuredness of water. This cosolvent effect is abolished in the presence of 0.18% Surfal due to the formation of inverted mixed micelles of detergent with cholesterol.
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PMID:Cholesterol oxidase: thermochemical studies and the influence of hydroorganic solvents on enzyme activity. 66 94

Acetonitrile extracts of cigarette tar inhibit state 3 and state 4 respiration of intact mitochondria. Exposure of respiring submitochondrial particles to acetonitrile extracts of cigarette tar results in a dose-dependent inhibition of oxygen consumption and reduced nicotinamide adenine dinucleotide (NADH) oxidation. This inhibition was not due to a solvent effect since acetonitrile alone did not alter oxygen consumption or NADH oxidation. Intact mitochondria are less sensitive to extracts of tar than submitochondrial particles. The NADH-ubiquinone (Q) reductase complex is more sensitive to inhibition by tar extract than the succinate-Q reductase and cytochrome complexes. Nicotine or catechol did not inhibit respiration of intact mitochondria. Treatment of submitochondrial particles with cigarette tar results in the formation of hydroxyl radicals, detected by electron spin resonance (ESR) spin trapping. The ESR signal attributable to the hydroxyl radical spin adduct requires the presence of NADH and is completely abolished by catalase and to a lesser extent superoxide dismutase (SOD). Catalase and SOD did not protect the mitochondrial respiratory chain from inhibition by tar extract, indicating that the radicals detected by ESR spin trapping are not responsible for the inhibition of the electron transport. We propose that tar causes at least two effects: (1) Tar components interact with the electron transport chain and inhibit electron flow, and (2) tar components interact with the electron transport chain, ultimately to form hydroxyl radicals.
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PMID:The inhibitory effect of extracts of cigarette tar on electron transport of mitochondria and submitochondrial particles. 131 24

The reaction of alpha-tocopherol (alpha-T) with superoxide anion (O2-) in both dry acetonitrile and in aqueous acetonitrile solution is described. The O2- was generated by the electrochemical reduction of molecular oxygen in acetonitrile, using tetrabutylammonium bromide as an electrolyte. alpha-T was reacted with O2- either in dry acetonitrile or in a 10% aqueous acetonitrile solution. In dry acetonitrile, alpha-T was oxidized to a very unstable primary intermediate, which was further oxidized to a secondary, more stable intermediate. The formation of the secondary intermediate depended upon the presence of molecular oxygen. This intermediate readily converted into two compounds in equimolar amounts (designated A and B). The primary, very unstable intermediate was readily reduced again to alpha-T by treatment with LiAlH4 or ascorbic acid. However, the secondary intermediate or the stable oxidation products could not be reduced to alpha-T. In the 10% aqueous acetonitrile, alpha-T was oxidized to alpha-tocopheryl quinone, alpha-tocopherol dimer and alpha-tocopherol dihydroxy dimer, and an unknown compound. In the aqueous medium, no intermediates were formed by the action of O2-. The results of this study indicate that the reaction of alpha-T with O2- under aprotic conditions is different from that observed under protic conditions.
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PMID:alpha-Tocopherol oxidation mediated by superoxide anion (O2-). I. Reactions in aprotic and protic conditions. 132 70

Bacteria utilizing high concentrations of acetonitrile as the sole carbon source were isolated and identified as Chromobacterium sp. and Pseudomonas aeruginosa. Maximum growth was attained after 96 h of incubation and P. aeruginosa grew slightly faster than Chromobacterium sp. The strains were able to grow and oxidize acetonitrile at concentrations as high as 600 mM. However, higher concentrations inhibited growth and oxygen uptake. Degradation studies with (14C)acetonitrile indicated 57% of acetonitrile was degraded by Pseudomonas aeruginosa as compared to 43% by Chromobacterium. The isolates utilized different nitrile compounds as carbon substrates.
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PMID:Isolation and characterization of acetonitrile utilizing bacteria. 136 63

The present investigation deals with the suggested role of redox-cycling ubisemiquinones in mitochondrial O2-. generation. Due to the functional complexity of electron-transferring ubiquinones in the respiratory chain, model experiments were designed to study whether ubisemiquinones will directly react with oxygen, thereby generating O2-. radicals. Based on the fact that mitochondrial ubiquinone was reported to operate in an aprotic surrounding of the inner mitochondrial membrane, the reactivity of ubisemiquinones with oxygen was tested in water-free acetonitrile. Our results prove that autoxidation of ubisemiquinones requires the addition of protons to the non-polar reaction system. An experimental evaluation of the validity of this finding with respect to mitochondrial ubiquinones is impeded by the biochemical role that oxygen plays in the establishment of ubisemiquinone populations. To differentiate between a possible direct interaction of oxygen on redox-cycling ubisemiquinones and this indirect biochemical O2 effect, we have successfully introduced ferricyanide instead of oxygen to establish mitochondrial ubisemiquinone pools. Ubisemiquinones in this reaction system were not susceptible to oxygen and no O2-. radicals were released unless the inner mitochondrial membrane was protonated by toluene pretreatment. Since the inner mitochondrial membrane is normally not permeable to protons (which is a prerequisite of the chemiosmotic theory of energy conservation) based on our experiments we can exclude the involvement of redox-cycling ubisemiquinones in mitochondrial O2-. generation.
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PMID:Ubisemiquinones of the mitochondrial respiratory chain do not interact with molecular oxygen. 151 50

A series of 4-(diarylmethyl)-1-[3-(aryloxy)propyl]piperidines and structurally related compounds were synthesized as calcium-channel blockers and antihypertensive agents. Compounds were evaluated for calcium-channel-blocking activity by determining their ability to antagonize calcium-induced contractions of isolated rabbit aortic strips. The most potent compounds were those with fluoro substituents in the 3- and/or 4-positions of both rings of the diphenylmethyl group. Bis(4-fluorophenyl)acetonitrile analogue 79 was similar in potency to bis(4-fluorophenyl)methyl compound 1. The methylene analogue of 1 (78) and derivatives of 1 that contained a hydroxyl (76), carbamoyl (80), amino (81), or acetamido (82) substituent on the methyl group were less potent. In most cases, substituents on the phenoxy ring, changes in the distance between the aryloxy group and the piperidine nitrogen, and the substitution of S, N(CH3), or CH2 for the oxygen atom of the aryloxy group had only a small to moderate effect on the potency. The best compounds in this series were more potent than verapamil, diltiazem, flunarizine, and lidoflazine, but were less potent than nifedipine. Compounds were evaluated for antihypertensive activity in spontaneously hypertensive rats (SHR) at an oral dose of 30 mg/kg. Of the 55 compounds tested, only nine produced a statistically significant (p less than 0.05) reduction in blood pressure greater than 20%; all of these compounds had fluoro substituents in both rings of the diphenylmethyl group. One of the most active compounds in the SHR at 30 mg/kg was 1-[4-[3-[4-[bis(3,4-difluorophenyl)methyl]-1- piperidinyl]propoxy]-3-methoxyphenyl]ethanone (63), which produced a 35% reduction in blood pressure and was similar in activity to nifedipine. At lower doses, however, 4-[bis(4-fluorophenyl)methyl]-1-[3-(4-chlorophenoxy)propyl]piperidine (93) was one of the most effective antihypertensive agents, producing reductions in blood pressure of 17 and 11% at oral doses of 10 and 3 mg/kg, respectively; 63 was inactive at 10 mg/kg.
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PMID:Synthesis, calcium-channel-blocking activity, and antihypertensive activity of 4-(diarylmethyl)-1-[3-(aryloxy)propyl]piperidines and structurally related compounds. 192 Mar 52

One of the active oxygen species, superoxide (O2-), was generated by the electrolytic reduction of molecular oxygen in acetonitrile. O2- was determined by the ultraviolet (UV) (lambda max/nm = 255, epsilon = 1.48 x 10(3) M-1 cm-3) and the electron spin resonance (ESR) (g parallel = 2.083, g perpendicular = 2.008) spectrum. O2- could easily react with tocopherols (vitamin E and its derivatives) to give the corresponding chromanoxyl radicals of which structures were determined by ESR. ESR studies of the reactions of O2- with tocopherols or their model compounds indicate that the radical concentrations from tocopherol models correlate with the physiological activities of the tocopherols. O2- could also react with some biologically active quinones such as vitamin K3 and vitamin E quinone to give the corresponding semiquinone radicals. The fact that vitamin E quinone, an irreversible metabolite of vitamin E, was reduced by O2- to the semiquinone radical suggests that, like vitamin E, vitamin E quinone may also scavenge O2- and protect living cells from the effects of O2- in a hydrophobic environment. Further, O2- could react with some metalloporphyrins. In this case, non-redox metalloporphyrins such as Zn(II)TPP (TPP: tetraphenylporphine), Cd(II)TPP, Mg(II)TPP generated the superoxide adduct by the reaction with O2-. On the other hand, redox-active metalloporphyrins such as Cr(III)TPP.Cl, Mn(III)TPP.Cl, Co(II)TTP TTP: tetra-p-tolylporphine) and Co(III)TTP.Cl underwent the addition and/or redox reactions with O2-. Another active oxygen species, hydroxyl radical (OH.), was first detected from some copper (II) coplexes such as Cu(en)2 (en: ethylenediamine) with hydrogen peroxide (H2O2) by ESR spin trapping and thiobarbituric acid (TBA) methods. Further, by using Cu(en)2-H2O2 system the most active OH. scavenger was determined. This Cu(en)2-H2O2 system will be useful for determing the antioxidant ability against OH..
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PMID:[Studies on the activation of molecular oxygen and the biological defence mechanism against active oxygen species]. 217 87

The photochemistry (Type I and II) of anthralin and its photo-oxidation product 1,8-dihydroxyanthraquinone (1,8-DHAQ) has been studied in ethanol, acetonitrile and dimethylsulfoxide using spin-trapping and direct detection of singlet oxygen (1O2) luminescence techniques. In ethanol, where it exists in its neutral form (AN), anthralin does not undergo either Type I or II reactions upon UV-irradiation. In contrast, irradiation of anthralin in acetonitrile, a solvent in which anthralin is partially converted to its corresponding mono-anion (AN-), generates both superoxide and singlet oxygen. Irradiation of anthralin in dimethylsulfoxide, where the AN- form is present in substantial quantity, generates superoxide and solvent derived radicals but no detectable singlet oxygen. UV-irradiation of 1,8-DHAQ in ethanol and acetonitrile produces both superoxide and singlet oxygen in significant yields. In dimethylsulfoxide, on the other hand, only superoxide and solvent derived radicals are observed. The 1O2 quantum yield for AN- and 1,8-DHAQ in acetonitrile were determined to be 0.14 and 0.88 relative to rose bengal in the same solvent. These findings suggest that the AN photosensitization occurs via Type I and II pathways, is solvent dependent and involves AN- as well as its oxidation product 1,8-DHAQ, which is a more potent generator of both singlet oxygen and superoxide.
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PMID:Spectroscopic studies of cutaneous photosensitizing agents--XV. Anthralin and its oxidation product 1,8-dihydroxyanthraquinone. 228 37

The quantum yield of triplet formation, phi T, and that of the photosensitized formation of singlet molecular oxygen, phi delta, were determined for a rare nucleoside, 4-thiouridine (4t-Urd), in water and in acetonitrile, using singlet molecular oxygen phosphorescence, laser-induced optoacoustics and time-resolved thermal lensing. These yields, phi T and phi delta, the latter in aerated solutions, were found to be, respectively, in water: 0.67 +/- 0.17 and 0.18 +/- 0.04 and in acetonitrile: 0.61 +/- 0.15 and 0.50 +/- 0.20. The fraction of the 4t-Urd triplet molecules quenched by oxygen leading to singlet molecular oxygen, S delta, was calculated to be between 0.7 and unity in both solvents, this value being indicative of a pi pi*character for the lowest triplet state of 4t-Urd.
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PMID:Quantum yields of triplet and O2(1 delta g) formation of 4-thiouridine in water and acetonitrile. 236 60


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