Showing papers on "Hydrogen peroxide published in 1991"
TL;DR: Peroxynitrite anion was a less effective thiol-oxidizing agent than its anion, with oxidation presumably mediated by the decomposition products, hydroxyl radical and nitrogen dioxide.
2,487 citations
TL;DR: The catalase assay performed using polarographic and spectrophotometric determination of hydrogen peroxide yielded a good correlation and in 742 healthy individuals the mean and SD values of serumCatalase were 50.5 +/- 18.1 kU/l with 17.7% higher activity in males than in females.
1,780 citations
TL;DR: In this article, the epoxidation of propylene with hydrogen peroxide in the liquid phase, in the presence of titanium silicalite catalyst (TS-1), is described.
681 citations
Patent•
03 Sep 1991
TL;DR: In this paper, a peroxidase was used to selectively oxidize ascorbate, urate, bilirubin, and acetaminophenol in the presence of glucose.
Abstract: Interferant eliminating analyte sensors and sensing process prevent erroneous assays. Glucose electrodes were coated with an oxidizing enzyme (peroxidase) which allows hydrogen peroxide to selectively oxidize ascorbate, urate, bilirubin, and acetaminophenol in the presence of glucose. Hydrogen peroxide may be added to the assayed solution or generated in situ. The oxidizing enzyme was prevented from causing undesired reduction currents at the glucose electrode by preventing contact of the oxidizing enzyme with the glucose electrode, or by increasing the applied voltage.
538 citations
TL;DR: It is proposed that Cu2+ ions bound to the DNA react with H2O2 and ascorbic acid to generate hydroxyl radicals, which then immediately attack the DNA bases in a site-specific manner.
Abstract: Mixtures of Cu2+ and H2O2 at pH 7.4 caused damage to the bases in DNA greater than that caused by mixtures of Fe3+ and H2O2. Addition of ascorbic acid to the Cu2+/H2O2 system caused a very large increase in base damage, much greater than that produced by the Fe3+/H2O2/ascorbic acid system. The products of base damage in the presence of Cu2+ were typical products that have been shown to result from attack of hydroxyl radicals upon the DNA bases. Cytosine glycol, thymine glycol, 8-hydroxyadenine and especially 8-hydroxyguanine were the major products in both the Cu2+/H2O2 and the Cu2+/H2O2/ascorbic acid systems. Base damage in DNA by these systems was inhibited by the chelating agents EDTA and nitrilotriacetic acid and by catalase, but not by superoxide dismutase, nor by the hydroxyl-radical scavenger mannitol. It is proposed that Cu2+ ions bound to the DNA react with H2O2 and ascorbic acid to generate hydroxyl radicals, which then immediately attack the DNA bases in a site-specific manner. A hypoxanthine/xanthine oxidase system also caused damage to the DNA bases in the presence of Cu2+ ions. This was inhibited by superoxide dismutase and catalase. The high activity of Cu2+ ions, when compared with Fe3- ions, in causing hydroxyl-radical-dependent damage to DNA and to other biomolecules, means that the availability of Cu2+ ions in vivo must be carefully controlled.
486 citations
TL;DR: The results showed that metmyoglobin and oxymyoglobin were activated by H2O2 to ferryl myoglobin, which initiates membrane lipid peroxidation; but not nitric oxide-myoglobin,Which, during interaction with H2 O2, did not form ferryl but meetmyoglobin which only poorly affected lipid per oxidation.
428 citations
TL;DR: After cold treatment of seedlings of winter wheat, levels of hydrogen peroxide in the leaves were measured and the elevated level was found to be equivalent to 1.5 micromoles per gram fresh weight tissues of leaves.
Abstract: After cold treatment of seedlings of winter wheat (Triticum aestivum L.), levels of hydrogen peroxide in the leaves were measured. The concentration of hydrogen peroxide increased to about three times the control level within a few minutes, and returned to the normal level in 15 to 20 minutes. The elevated level of hydrogen peroxide was found to be equivalent to 1.5 micromoles per gram fresh weight tissues of leaves.
407 citations
TL;DR: In vitro, a potentially implantable, needle-type amperometric enzyme electrode which is suitable for continuous monitoring of glucose concentrations in diabetic patients and suffered no significant loss of response over periods of up to 60 h is constructed.
328 citations
TL;DR: A new hypothesis has been formulated for the pathogenesis of vitiligo based on a consistent reduction in levels of catalase compared to normal healthy controls of matched photo-skin types and a increase in the concentration of hydrogen peroxide in the epidermis of these patients.
307 citations
TL;DR: In this paper, a stoichiometric amount of iodide plus propylene oxide in the absence of air was shown to be superior to a catalytic amount of iodine in the air.
Abstract: To photocyclize stilbenes, a stoichiometric amount of iodine plus propylene oxide in the absence of air is superior to a catalytic amount of iodine in the air. The propylene oxide prevents HI from photoreducing double bonds. The absence of air prevents photooxidative side reactions, shown in one case to be caused by a photogenerated oxidant, possibly hydrogen peroxide
291 citations
TL;DR: The results suggest that an iron chelate and another as yet unidentified form of iron are both required for maximal rates of amino acid oxidation, and amino acids may serve an important role in antioxidant defense against tissue damage.
TL;DR: It appears that acetic acid whose pKa is higher than that of lactic acid exhibits the highest inhibitory activity, while 8acteriocins are the last type of inhibitory substance produced by some lactie acid bacteria.
Abstract: Summary - Lactic acid bacteria can produce a variety of antimicrobial compounds which may affect both the lactic acid bacteria themselves as weil as undesirable or pathogenic strains. In this first section, we describe the biosynthesis, mode of action and activity spectra of these inhibitors. Metabolites of oxygen (hydrogen peroxide and free radicals) exhibit a bacteriostatic or bactericidal activity against lactic or non-Iactic flora. When associated with the lactoperoxidase/thiocyanate system, hydrogen peroxide leads to the formation of inhibitory compounds which are bacteriostatic for lactic acid bacteria and bactericidal for Gram-negative bacteria. The antimicrobial activity of organic acids (Iactic, acetic and formic) and of pH are closely linked. It appears that the non-dissociated fraction of these acids is the major inhibitory form. Thus, acetic acid whose pKa is higher than that of lactic acid exhibits the highest inhibitory activity. The antimicrobial activities of diacetyl, acetaldehyde and of the D isomers of amino acids are also described, although their effects are slight in usual lactic fermentations. 8acteriocins are the last type of inhibitory substance produced by some lactie acid bacteria. They will be described in a second section. lactic acid bacteria / oxygen 1acidity 1diacetyll acetaldehyde
TL;DR: Titanium silicalite catalyses the oxidation of alkanes, alkylbenzenes, 1-chlorohexane, and methyl heptanoate with hydrogen peroxide, at very mild conditions as discussed by the authors.
TL;DR: Modification of DNA bases in mammalian chromatin upon treatment with hydrogen peroxide in the presence of ferric and cupric ions was studied, indicating a possible site-specific formation of hydroxyl radical when metal ions are bound to chromatin.
TL;DR: Yields and size distributions of human and bovine serum albumin microbubbles have been determined as a function of various experimental parameters.
Abstract: Air-filled microbubbles are in clinical use as echo-contrast agents for sonographic applications. The synthesis of aqueous suspensions of air-filled proteinaceous microbubbles involves the ultrasonic irradiation of aqueous protein solutions in the presence of O2. Yields and size distributions of human and bovine serum albumin microbubbles have been determined as a function of various experimental parameters. The chemical nature of these microbubbles and the origin of their remarkably long lifetimes have been explored. The microbubbles are held together primarily by interprotein cross-linking of cysteine residues. The principal cross-linking agent is superoxide created by the extremely high temperatures produced during acoustic cavitation.
TL;DR: Overall, the results show that ergothioneine at the concentrations present in vivo could act as an antioxidant.
TL;DR: In this paper, the formation and occurrence of hydroperoxides in the troposphere have been studied by laboratory experiments and by preliminary field measurements, and preliminary measurements of hydrogen peroxide and five organic H2O2 in ambient air were made at Niwot Ridge, Colorado from 24 July-4 August 1989.
Abstract: The formation and occurrence of hydroperoxides in the troposphere have been studied by laboratory experiments and by preliminary field measurements. Nine alkenes were reacted individually with ozone in a reaction chamber in the presence of excess water, and the amounts of hydrogen peroxide and of nine organic hydroperoxides produced in the gas and aerosol phases and deposited on the chamber walls determined by HPLC. The reactions of ethene, propene, 1-butene and isoprene gave hydroxymethyl hydroperoxide as the major product with no hydrogen peroxide observed. In the case of α- and β-pinene, 2-carene and limonene the major product was hydrogen peroxide. Cis-2-butene produced hydrogen peroxide and methyl hydroperoxide. Preliminary measurements of hydrogen peroxide and five organic hydroperoxides in ambient air were made at Niwot Ridge, Colorado from 24 July–4 August 1989. The gas-phase species were preconcentrated by cryotrapping with subsequent HPLC separation. The gas-phase concentrations of H2O2 ranged from 0.5–2 ppbv with the lowest concentrations being measured at night and the highest under conditions of strong photochemical activity. The maximum concentrations of hydroxymethyl hydroperoxide approximated those of H2O2. Methyl hydroperoxide concentrations ranged from <50 to 800 pptv and three other organic hydroperoxides were detected at concentrations below 200 pptv. High volume aerosol samples yielded H2O2 and methyl hydroperoxide concentrations <10 ng m-3 while H2O2 and six organic species were detected in rainwater at concentrations in the range <0.01–50 μM.
TL;DR: The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized and hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.
Abstract: The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized. Ozonolysis of emulsions of methyl oleate yields approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone used and fatty acid reacted. That is, the net equation that occurs is RCH = CHR' + O3 + H2O----RCHO + R'CHO + H2O2 . Ozonolysis of emulsions of oleic, linoleic, linolenic, and arachidonic acids gives 1 mol of hydrogen peroxide per mole of ozone used. Only very low yields (less than 5%) of reducible materials other than hydrogen peroxide are observed, suggesting that the yields of organic peroxidic materials, including Criegee ozonides and lipid hydroperoxides, are small. Ozonolysis of rat erythrocyte ghost membranes and rat bronchoalveolar lavage also gives significant yields (about 50%) of hydrogen peroxide based on the moles of ozone consumed. Reactions of ozone with bovine serum albumin, glutathione, and glucose do not produce hydrogen peroxide, implying that the hydrogen peroxide formed during the ozonation of biological materials arises almost exclusively from ozone/olefin reactions. Hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.
01 Jan 1991
TL;DR: Aconitase was purified over 135fold to a specific activity of 32 mumol/min per mg (with isocitrate as substrate) from the matrix of potato tuber mitochondria.
Abstract: Preincubation of potato (Solanum tuberosum) tuber mitochondria with 300 microM-H2O2 for 10 min nearly stopped the State 3 rate of citrate oxidation. Addition of isocitrate resulted in resumption of O2 uptake. The State 3 rates of succinate, external NADH and 2-oxoglutarate oxidation were unaffected by H2O2 over the dose range 50-500 microM. Preincubation of mitochondria with 300 microM-H2O2 for 5 min unmasked in the matrix space a paramagnetic signal with a peak at a g value of approx. 2.03. Aconitase was purified over 135-fold to a specific activity of 32 mumol/min per mg (with isocitrate as substrate) from the matrix of potato tuber mitochondria. The native enzyme was composed of a single polypeptide chain (molecular mass 90 kDa). Incubation of purified aconitase with small amounts of H2O2 caused the build up of a paramagnetic 3Fe cluster with a low-field maximum of g = 2.03 leading to a progressive inhibition of aconitase activity. The results show that aconitase present in the matrix space was the major intramitochondrial target for inactivation by H2O2.
TL;DR: It is found that ozonations of emulsions of fatty acids containing from one to four double bonds give one mole of H2O2 for each mole of ozone reacted, which agrees with expectations.
TL;DR: The changes observed suggest that there may be interaction between resin and residual peroxide at or near the enamel surface.
TL;DR: Titano-Silicalite 1 (TS-1) has been used as a catalyst for the hydroxylation of phenol with hydrogen peroxide as mentioned in this paper, which was carried out in different organic solvents in order to investigate the solvent effect and its influence on the product distribution during the oxidation.
TL;DR: The sea urchin egg uses an oxidative cross-linking reaction that requires hydrogen peroxide and a secreted peroxidase and thus faces the challenge of oxidant stress at the beginning of its development.
Abstract: Metazoan eggs alter their coats after fertilization to protect the early embryo. In sea urchins, this modification consists of a rapid, coordinated set of noncovalent macromolecular assembly steps that are stabilized by protein cross-linking. The sea urchin egg uses an oxidative cross-linking reaction that requires hydrogen peroxide and a secreted peroxidase and thus faces the challenge of oxidant stress at the beginning of its development. Protection from the deleterious effects of this oxidative mechanism is afforded by regulation of the production and utilization of oxidizing species. This regulation requires a specific protein kinase C-activated oxidase and ovothiol, an intracellular antioxidant.
TL;DR: Cyanobacteria can be divided into two groups, those that has and those that lacks AsA peroxidase, and the second group only scavenges hydrogen peroxide with catalase.
Abstract: Cyanobacteria can be divided into two groups, those that has and those that lacks AsA peroxidase. The first group scavenges hydrogen peroxide with the peroxidase using a photoreductant as the electron donor, and the second group only scavenges hydrogen peroxide with catalase
TL;DR: The nature of chromium(VI)-induced DNA damage appears to be dependent on the reactive intermediates, i.e. chromium (V) or hydroxyl radical, produced during the reduction of chromation(VI).
Abstract: The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI...