Showing papers on "Hydrogen peroxide published in 1977"
TL;DR: Evidence for the role of ubiquinone as peroxide generator is provided by the generation of O 2 − and H 2 O 2 during autoxidation of quinols.
837 citations
TL;DR: The onset of ripening correlates with the peroxide content of fruit tissues as occurring under normal conditions or as influenced by the treatments, indicating that Hydrogen peroxide may be involved in oxidative processes required in the initiation and the promotion of ripens.
Abstract: Endogenous peroxide levels in pear fruit (Pyrus communis) were measured using a titanium assay method, and were found to increase during senescence in both Bartlett and Bosc varieties. Application of glycolic acid or xanthine, serving as substrates for the formation of H2O2, increased the peroxide content of the tissue and accelerated the onset of ripening, as measured by increased softening and ethylene evolution. Application of ethylene also induced increased peroxide levels. Ripening processes were similarly promoted when peroxides were conserved by inhibiting the activity of catalase with hydroxylamine or potassium cyanide. By comparison, the inhibition of glycolate oxidase with alphahydroxy-2-pyridinemethanesulfonic acid decreased the peroxide content of the tissue and delayed the onset of ripening. These results indicate that the onset of ripening correlates with the peroxide content of fruit tissues as occurring under normal conditions or as influenced by the treatments. Hydrogen peroxide may be involved in oxidative processes required in the initiation and the promotion of ripening.
664 citations
TL;DR: Results indicate that with normal cells approximately 50% of H(2)O( 2) released during phagocytosis is derived directly from O(2.) (-) by dismutation, the remainder appearing from an (intra)cellular source shared by azide-inhibitable heme enzymes.
Abstract: Normal and cytochalasin B-treated human granulocytes have been studied to determine some of the interrelationships between phagocytosis-induced respiration and superoxide and hydrogen peroxide formation and release into the extracellular medium by intact cells. By using the scopoletin fluorescent assay to continuously monitor extracellular hydrogen peroxide concentrations during contact of cells with opsonized staphylococci, it was demonstrated that the superoxide scavengers ferricytochrome c and nitroblue tetrazolium significantly reduced the amount of H(2)O(2) released with time from normal cells but did not abolish it. This inhibitory effect was reversed by the simultaneous addition of superoxide dismutase (SOD), whereas the addition of SOD alone increased the amount of detectable H(2)O(2) in the medium. The addition of sodium azide markedly inhibited myeloperoxidase-H(2)O(2)-dependent protein iodination and more than doubled H(2)O(2) release, including the residual amount remaining after exposure of the cells to ferricytochrome c, suggesting its origin from an intracellular pool shared by several pathways for H(2)O(2) catabolism. When cells were pretreated with cytochalasin B and opsonized bacteria added, reduced oxygen consumption was observed, but this was in parallel to a reduction in specific binding of organisms to the cells when compared to normal. Under the influence of inhibited phagosome formation by cytochalasin B, the cells released an increased amount of superoxide and peroxide into the extracellular medium relative to oxygen consumption, and all detectable peroxide release could be inhibited by the addition of ferricytochrome c. Decreased H(2)O(2) production in the presence of this compound could not be ascribed to diminished bacterial binding, decreased oxidase activity, or increased H(2)O(2) catabolism and was reversed by the simultaneous addition of SOD. Furthermore, SOD and ferricytochrome c had similar effects on another H(2)O(2)-dependent reaction, protein iodination, in both normal and cytochalasin B cells. When oxygen consumption, O(2.) (-), and H(2)O(2) release were compared in the presence of azide under identical incubation conditions, the molar relationships for normal cells were 1.00:0.34:0.51 and for cytochalasin B-treated cells 1.00:0.99:0.40, respectively. Nonopsonized, or opsonized but disrupted, bacteria did not stimulate any of these metabolic functions. The results indicate that with normal cells approximately 50% of H(2)O(2) released during phagocytosis is derived directly from O(2.) (-) by dismutation, the remainder appearing from an (intra)cellular source shared by azide-inhibitable heme enzymes. With cytochalasin B treatment the evidence is consistent with the derivation of all H(2)O(2) from an O(2.) (-) precursor which is released from the cell surface. Furthermore, when activated by phagocytic particle binding, the neutrophil O(2.) (-) generating system appears to make more of this compound than can be accounted for by dismutation to H(2)O(2). This establishes conditions for the direct participation of both compounds in the microbicidal and cytocidal activity of these cells.
568 citations
TL;DR: The experiments suggest that the formation of oxygen radicals followed by lipid peroxidation may be the basis for the cardiotoxic effects of these drugs.
536 citations
TL;DR: It was realized that this assay could be easily interfered by endogenous hydrogen donor of the horseradish peroxidase and by exogenous hydrogen donors in the mitochondrial preparations, and consequently, an alternative method was developed.
Abstract: The development and application of sensitive methods for the determination of hydrogen peroxide led, a few years ago in the laboratories of the Johnson Research Foundation, to the recognition, of intact mitochondria as an effective source of H2O2 (Fig. 1; refs. 1–4). Previous observations by Jensen (5) and by Hinkle et al. (6) had indicated that the mitochondrial respiratory chain was capable of producing H2O2. However, these results were taken with caution, in the sense that they might reflect an artificial activity induced by the ultrasonic or alkaline treatment used in the preparation of the submitochondrial particles. In 1971, Chance and Oshino (1) demonstrated variations in the level of the catalase intermediate of the peroxisomal-mitochondrial fraction of rat liver following the addition of mitochondrial substrates and uncouplers. In the same year, Loschen et al. (2) showed H2O2 formation in pigeon heart mitochondria and its relationship to the mitochondrial metabolic state by using the peroxidase-scopoletin method. It was realized that this assay could be easily interfered by endogenous hydrogen donor of the horseradish peroxidase and by exogenous hydrogen donors in the mitochondrial preparations, and consequently, an alternative method was developed.
415 citations
TL;DR: Hydrogen peroxide activates this enzymatic reaction in cell-free extracts prepared from abalone eggs, and this effect appears to reveal a fundamental property of prostaglandin endoperoxide synthesis.
Abstract: Addition of hydrogen peroxide to seawater causes synchronous spawning in gravid male and female abalones, and certain other mollusks as well. This effect is blocked by exposure of the animals to aspirin, an inhibitor of the enzyme catalyzing oxidative synthesis of prostaglandin endoperoxide. Hydrogen peroxide activates this enzymatic reaction in cell-free extracts prepared from abalone eggs (a very rich source of the prostaglandin endoperoxide synthetase); this effect appears to reveal a fundamental property of prostaglandin endoperoxide synthesis. Applicability of these findings to both mariculture and medical purposes is suggested.
257 citations
TL;DR: An enhanced production of superoxide and hydrogen peroxide and the relatively low catalase content of heart tissue may be factors in the cardiotoxicity induced by adriamycin chemotherapy if a similar reaction occurs in vivo.
254 citations
TL;DR: A modification of the method of catalase determination by means of the Clark oxygen electrode is described, based on measurement of the initial rate at which oxygen is released bycatalase in an oxygen-free buffer, which is applicable to an 840-fold range ofCatalase concentrations.
236 citations
TL;DR: When benzylamphetamine alone is added in control experiments to correct for the NADPH and O 2 consumption not associated with benzphetamine hydroxylation, the expected 1:1:1 stoichiometry for NADPH oxidation, O 2 Consumption, and formaldehyde formation in the hydroxyation reaction is observed.
192 citations
TL;DR: In this paper, a mechanism for the electrochemical oxidation of oxalate at a platinum electrode in acetonitrile solutions was proposed, which showed an irreversible two-electron oxidation at ca. 0.3 V vs. SCE to CO2 with no intermediates detectable by these techniques.
Abstract: The electrochemical oxidation of oxalate at a platinum electrode in acetonitrile solutions as studied by cyclic and rotating-ring disk voltammetry and controlled potential coulometry shows an irreversible two-electron oxidation at ca. 0.3 V vs. SCE to CO2 with no intermediates detectable by these techniques. The oxidation of oxalate in the presence of several fluorescers (such as rubrene, 9, IO-diphenylanthracene, and the bipyridyl chelates of ruthenium(l1) and osmium(l1)) does not produce light, but emission characteristic of the fluorescer occurs during the simultaneous oxidation of the additive and oxalate. Studies of the conditions for emission in the presence of thianthrene and naphthalene lead to a mechanism for the oxidation of oxalate and the excitation process based on oxidation of oxalate to CzO4-., which undergoes rapid decomposition to COz and C02--. The C02-e can transfer an electron to the additive molecule to produce a radical anion, which can then undergo an ecl annihilation reaction with the electrogenerated radical cation. There has been much interest in the intense chemiluminescence which results from the reaction of oxalyl chloride or oxalate esters and hydrogen peroxide in the presence of fluorescent compounds in nonaqueous solvents.’-3 In the proposed mechanism for these processes, the reaction between the oxalate ester and H202 produces the dioxetanedione (1) as an
185 citations
Patent•
26 Sep 1977
TL;DR: In this paper, a method of sterilizing the surfaces of articles such as medical intruments and other products by exposing such surfaces to hydrogen peroxide gas at temperatures below 80° C. in a temperature range that is generally considered nonsporicidal is presented.
Abstract: A method of sterilizing the surfaces of articles such as medical intruments and other products by exposing such surfaces to hydrogen peroxide gas at temperatures below 80° C. in a temperature range that is generally considered nonsporicidal.
TL;DR: In this article, the authors studied the kinetics of the oxidation of hydrogen sulfide and hydrosulfide ion to sulfur and sulfate in aqueous solution by hydrogen peroxide.
Abstract: The kinetics of the oxidation of hydrogen sulfide and hydrosulfide ion to sulfur and sulfate in aqueous solution by hydrogen peroxide is studied potentiometrically. In the pH range 8-3, the rate law for the oxidation of H_2S is -d[H_2S]/dt = k_1[H_2S] [H_2O_2] + k_2K_(a1)[H_2S] [H_2O_2]/[H+] where K_(a1) is the first acid dissociation constant of H_S, k_2 = 29.0 M^(-1) min^(-1), and k_1= 0.5 M^(-1) min^(-1). The rate law and other data indicate that the reaction proceeds via a nucleophilic displacement by sulfide on hydrogen peroxide with the formation of polysulfide intermediates.
TL;DR: Using an assay system of ethylene generation from methional, cell preparations of human monocytes were demonstrated to generate hydroxyl radical or a similar agent during phagocytosis of zymosan particles, and monocytes from a patient with chronic granulomatous disease failed to generate ethylene.
Abstract: A number of highly reactive oxygen species have been implicated in the oxygen-dependent mechanisms involved in bactericidal activity of phagocytic leukocytes Hydrogen peroxide and superoxide, two agents known to occur during phagocytosis, are thought to interact to generate hydroxyl radical, singlet oxygen, and other potentially reactive molecules Using an assay system of ethylene generation from methional, cell preparations of human monocytes were demonstrated to generate hydroxyl radical or a similar agent during phagocytosis of zymosan particles The generation of ethylene was impaired by agents which reduce superoxide or hydrogen peroxide concentrations as well as by agents reported to be hydroxyl radical scavengers The ethylene generation did not appear to be dependent on myeloperoxidase in that azide enhanced ethylene generation Monocytes from a patient with chronic granulomatous disease failed to generate ethylene during phagocytosis This assay technique may be useful in exploring the metabolic events integral to the bactericidal and inflammatory activity of phagocytic leukocytes
TL;DR: There was no loss of radioactivity from the fixed cells with hydrogen peroxide treatment, and in the smaller-sized cell ranges there was a significant reduction in apparent adipocyte number of rat, pig, and beef adipose tissue with 8 M urea treatment.
TL;DR: The initial step in the lactoperoxidase catalysed oxidation of thiocyanate by hydrogen peroxide by H2O2 leads to the formation of hypothiOCyanite.
Abstract: The initial step in the lactoperoxidase (LPO) catalysed oxidation of thiocyanate (SCN––) by hydrogen peroxide (H2O2) leads to the formation of hypothiocyanite (OSCN
TL;DR: The results indicated that a combination of NaOCl and H 2 O 2 was significantly more effective in cleansing the canal system at 1 and 3 mm from the apex.
TL;DR: It is suggested that peroxidase catalyzes the oxidation of hydrogen donors to form free radicals or quinones, which subsequently interact with, cross link, and alter the soluble proteins.
Abstract: The enzyme peroxidase, a substrate (hydrogen donor), and hydrogen peroxide aggregated and polymerized soluble proteins included in the reaction mixture. Gel filtration and acrylamide disk gel electrophoresis revealed newly formed dimers, trimers, and higher protein polymers. Some of the protein polymers withstood the denaturing conditions of dodecyl sulfate disk gel electrophoresis; thus the formation of some covalent cross links was indicated. It is suggested that peroxidase catalyzes the oxidation of hydrogen donors to form free radicals or quinones, which subsequently interact with, cross link, and alter the soluble proteins.
Journal Article•
TL;DR: In this paper, the reactions of lignins upon treatment with oxygen and hydrogen peroxide in alkaline media are summarized on the basis of the results from studies with appropriate model compounds, and two types of initial oxidation reactions may be distinguished: (1) Electrophilic attack on carbanions by molecular oxygen (oxygenations) (2) Nucleophilic addition of hydroperoxide anions to carbonyl and conjugated carbonyls structures.
Abstract: The reactions of lignins upon treatment with oxygen and hydrogen peroxide in alkaline media are summarized on the basis of the results from studies with appropriate model compounds. Two types of initial oxidation reactions may be distinguished: (1) Electrophilic attack on carbanions by molecular oxygen (oxygenations) (2) Nucleophilic addition of hydroperoxide anions to carbonyl and conjugated carbonyl structures. These two oxidants attack in phenolic and enolic lignin structures centres having alternately high (oxygen) and low (hydrogen peroxide) electron density. Both the reactions with oxygen and those with hydrogen peroxide result in the formation of intermediates of the hydroperoxide type. Subsequently, the intermediates undergo rearrangements, resulting in the cleavage of carbon-carbon bonds or in the formation of epoxide intermediates, or alternatively are converted into ortho-or para-quinoid structures. The products of the cleavage of carbon-carbon bonds and the quinoid and epoxide intermediates undergo alkaline-oxidative degradation ultimately yielding simple acids and hydrophilic polymerization products. The two types of initial oxidation (1 and 2) may take place simultaneously or sequentially, both during treatment with oxygen in alkali (oxygen pulping and bleaching). In the former process, hydrogen peroxide is generated by the autoxidation of enediol structures while, in the latter process, oxygen is originally present in the atmosphere and/or is formed by the decomposition of hydrogen peroxide. Although intimately connected with each other during both processes, these two types of oxidation reactions should be considered separately. By doing so, known observations from technical treatments of wood, pulps and lignins with oxygen or hydrogen peroxide can be interpreted in chemical terms.
TL;DR: It is concluded that a toxic product is formed in a reaction involving superoxide, hydrogen peroxide, and metal ions, which might be the Haber-Weiss reaction, O2- + H2O2 → OH + OH- + O2.
TL;DR: Compound I, obtained after molecular hydrogen peroxide and the enzyme diffuse together, involves a minimum of two bond ruptures and the formation of two new bonds, yet this amazing reaction proceeds with an activation energy equal to or less than that for the fluidity of water.
TL;DR: The effectiveness of hydrogen peroxide in oxidizing soil organic matter was markedly increased by the presence of 0.1M sodium pyrophosphate at pH 7, with residual C after treatment being reduced up to 20 times lower compared to conventional soil peroxidation.
Abstract: The effectiveness of hydrogen peroxide in oxidizing soil organic matter was markedly increased by the presence of 0.1M sodium pyrophosphate at pH 7, with residual C after treatment being reduced up to 20 times lower compared to conventional soil peroxidation. “Electropositive” (Orange II) and external (N₂) surface areas increased, whereas “electronegative” (cetyl pyridinium bromide) surface area values generally decreased after H₂O₂ treatment, supporting the assumption that metals released from organic matter may precipitate as hydroxide coatings that hinder further oxidation. Some soil sorption sites appear to be occluded by organic matter, so that changes in soil properties after peroxidation cannot be solely attributed to organic matter.
TL;DR: The dithionite-induced absorption maximum at 460 nm, present in the active enzyme, was lost upon inactivation of the enzyme, the first direct indication of the involvement of cytochrome P 460 in the action of hydroxylamine oxidoreductase.
Abstract: Incubation of hydroxylamine oxidoreductase of Nitrosomonas with hydrogen peroxide resulted in the rapid and irreversible loss of the ability to catalyze the dehydrogenation of hydroxylamine in the presence of electron acceptors, such as phenazine methosulfate. The rate of the reaction was dependent on the concentration of enzyme and H2O2. Inactivation occurred most rapidly at pH values between 9 and 10. Inactivation of the enzyme by H2O2 did not result in alteration of absorption spectrum of either the oxidized form of the enzyme or dithionite-reduced enzyme cytochromes with alpha maxima in the wavelength range 540-570 nm, indicating that those cytochromes were not directly involved in the dehydrogenase step. In contrast to the active enzyme, cytochromes with alpha maxima in the wavelength range 540-570 nm were not reducible by hydroxylamine in the inactivated enzyme. The dithionite-induced absorption maximum at 460 nm (cytochrome P 460), present in the active enzyme, was lost upon inactivation of the enzyme. This is the first direct indication of the involvement of cytochrome P 460 in the action of hydroxylamine oxidoreductase. Protection from inactivation was afforded by (a) substrates for the reduction of enzyme cytochrome, hydrazine, and N-methylhydroxylamine; (b) metal binding agents, KCN, 1,2-dihydroxybenzene-3,5-disulfonate, and hydroxyurea; (c) reductants, o-dianisidine, p-phenylenediamine, hydroquinone, pyrogallol, and dithiothreitol; (d) electron acceptors, phenazine methosulfate, and 2,6-dichlorophenolindophenol; and (e) the singlet oxygen trapping agent, 1,3-diphenylfuran. Scavengers of superoxide anion or hydroxyl radical did not protect the enzyme from inactivation.
TL;DR: In this paper, the authors studied the reaction of two dialkylthioureas to their respective formamidine disulfide cations by hydrogen peroxide in acid solution and showed that the reactions proceed via a nucleophilic displacement by sulfur on oxygen.
Abstract: The oxidation of thiourea and two dialkylthioureas to their respective formamidine disulfide cations by hydrogen peroxide in acid solution has been studied kinetically. The rate law and other data indicate that the reactions proceed via a nucleophilic displacement by sulfur on oxygen. The scope of this mechanism for reaction of nucleophiles with peroxides is discussed.
TL;DR: If catalase was present in the suspension and the flow was adjusted to the rate of oxygen consumption, the cells grew at rates identical to the controls incubated under air.
Abstract: Oxygen has been supplied to suspensions of microorganisms kept under nitrogen by the addition of hydrogen peroxide. If catalase was present in the suspension and the flow was adjusted to the rate of oxygen consumption, the cells grew at rates identical to the controls incubated under air. The applicability of oxygen supply by hydrogen peroxide and its limits are discussed.
TL;DR: Measurements of superoxide dismutase activity indicate the presence of this enzyme in the ascites cell nuclei, although the sensitivity of adrenochrome formation to externally added superoxide Dismutase indicates that the endogenous enzyme is not sufficient for a complete protection from superoxide radicals.
TL;DR: The conditions required to obtain rhodanese inactivation in the presence of dithiothreitol indicate the involvement of hydrogen peroxide produced by metal-ion catalyzed oxidation ofdithiOTHreitol, which might be formed via a sulfenic intermediate.
TL;DR: The enzyme had a pH optimum at 6.3-6.5 and a maximum activity at 40°C and the apparent Km determined in the presence of ethanol was 0.015 μM as discussed by the authors.
Abstract: The activity of lipoxygenase extracted from tomato fruits can be twice as important according to tomato varieties. Differences between the last stages of ripening agree with the results previouslv reported. The partially purified enzyme (27-fold) is very unstable and can be protected during a limited time by ascorbic acid and EDTA. The fact that it is inhibited by hydrogen peroxide and not by cyanide ions (10-3 M) and EDTA (10-3M) is in favor of a true lipoxygenase and not a hematin compound. The molecular weight of the enzyme was estimated from gel filtration to be approximately 87,000. The enzyme had a pH optimum at 6.3–6.5 and a maximum activity at 40°C. The apparent Km determined in the presence of ethanol is 0.015 μM.
Patent•
28 Nov 1977
TL;DR: A stable aqueous peroxy-containing concentrate containing by weight of the concentrate 1 to 60 percent of perglutaric acid, 1 to 50 percent of hydrogen peroxide, and the remainder to 100 percent water is presented in this article.
Abstract: A stable aqueous peroxy-containing concentrate containing by weight of the concentrate 1 to 60 percent of perglutaric acid; 1 to 50 percent of hydrogen peroxide; 001 to 2 percent of a stabilizing agent for the perglutaric acid and hydrogen peroxide; and the remainder to 100 percent water