Showing papers on "Hydrogen peroxide published in 1984"
TL;DR: Methods for the estimation of hydrogen peroxide in acetone extracts using titanium(IV) are likely to overestimate hydrogenperoxide when applied to plant leaves because pigments appear to co-precipitate with the titanium complex and cannot be removed by washing with solvents.
1,008 citations
TL;DR: The C-8 position of deoxyguanosine (dGuo) was hydroxylated by ascorbic acid in the presence of oxygen (O2) in 0.1 M phosphate buffer in high yield with remarkably enhanced addition of hydrogen peroxide (H2O2).
Abstract: The C-8 position of deoxyguanosine (dGuo) was hydroxylated by ascorbic acid in the presence of oxygen (O2) in 0.1 M phosphate buffer (pH 6.8) at 37 degrees C. Addition of hydrogen peroxide (H2O2) remarkably enhanced this hydroxylation. The Udenfriend system [ascorbic acid, FeII, ethylenediaminetetraacetic acid (EDTA) and O2] was also effective for hydroxylation of dGuo in high yield. Guanine residues in DNA were also hydroxylated by ascorbic acid. Other reducing agents, such as hydroxylamine, hydrazine, dihydroxymaleic acid, sodium bisulfite and acetol, were also effective for the hydroxylation reaction, as were metal-EDTA complexes (FeII-, SnII-, TiIII-, CuI-EDTA). An OH radical seemed to be involved in this hydroxylation reaction in most of the above hydroxylating systems, but another reaction mechanism may also be involved, particularly when dGuo is hydroxylated by ascorbic acid alone or ascorbic acid plus H2O2. The possible biological significance of the hydroxylation of guanine residues in DNA in relation to mutagenesis and carcinogenesis is discussed.
924 citations
677 citations
TL;DR: Mitochondrial O 2 - production is pH dependent and increases toward the alkaline region, and effective inhibitors of Mn-superoxide dismutase are not known, and matrical superoxide dismUTase is usually removed by the repetitive washing of submitochondrial particles obtained by sonication or by other means.
Abstract: Publisher Summary The determination of the rate of O 2 - production is based upon the spectrophotometric measurement of oxidation or reduction reactions in which O 2 - is a reactant. The concentration of the spectrophotometric indicator that reacts with O 2 - is adjusted to compete effectively with the spontaneous dismutation of O 2 - so that nearly all O 2 - produced can be detected. The involvement of O 2 - is ascertained by the use of superoxide dismutase that inhibits the reaction rate specifically due to O 2 - . Cyanide, which is often used as inhibitor of the mitochondrial cytochrome oxidase ( K i about 3 x 10 -5 M) is also an inhibitor of the often used copper-containing superoxide dismutase ( K i about 3 × 10 -4 M). It is possible to use enough cyanide that partially inhibits cytochrome oxidase without inhibiting superoxide dismutase. Alternatively, bacterial or mitochondrial (manganese-containing) superoxide dismutase can be used. Mitochondria have Mn-superoxide dismutase in the matrix space, so to measure the total production of O 2 - by mitochondrial membranes, the dismutase should be inhibited or removed. Because effective inhibitors of Mn-superoxide dismutase are not known, matrical superoxide dismutase is usually removed by the repetitive washing of submitochondrial particles obtained by sonication or by other means. Mitochondrial O 2 - production is pH dependent and increases toward the alkaline region.
527 citations
TL;DR: Data indicate that alkaline peroxide pretreatment is a simple and efficient method for enhancing the enzymatic digestibility of lignocellulosic crop residues to levels approaching the theoretical maximum.
Abstract: Approximately one-half of the lignin and most of the hemicellulose present in agricultural residues such as wheat straw and corn stover are solubilized when the residue is treated at 25 degrees C in an alkaline solution of hydrogen peroxide. The delignification reaction is most efficient when the ratio of hydrogen peroxide to substrate is at least 0.25 (w/w) and the pH is 11.5. The supernatant fraction from a given pretreatment, after addition of makeup peroxide and readjustment of the pH, can be recycled to treat at least six additional batches of substrate, resulting in a substantial concentration of hemicellulose and soluble lignin degradation products. Hydrolysis of the insoluble fraction with Trichoderma reesei cellulase after alkaline peroxide treatment yields glucose with almost 100% efficiency, based upon the cellulose content of the residue before treatment. These data indicate that alkaline peroxide pretreatment is a simple and efficient method for enhancing the enzymatic digestibility of lignocellulosic crop residues to levels approaching the theoretical maximum.
413 citations
TL;DR: In this article, isolated human neutrophilic leukocytes were stimulated to produce hydrogen peroxide (H2O2) and to secrete cytoplasmic granule components including myeloperoxidase into the medium.
365 citations
TL;DR: Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation.
Abstract: The inactivation of catechol 2,3-dioxygenase from Pseudomonas putida mt-2 by 3-chloro- and 3-fluorocatechol and the iron-chelating agent Tiron (catechol-3,5-disulfonate) was studied. Whereas inactivation by Tiron is an oxygen-independent and mostly reversible process, inactivation by the 3-halocatechols was only observed in the presence of oxygen and was largely irreversible. The rate constants for inactivation (K2) were 1.62 × 10−3 sec−1 for 3-chlorocatechol and 2.38 × 10−3 sec−1 for 3-fluorocatechol. The inhibitor constants (Ki) were 23 μM for 3-chlorocatechol and 17 μM for 3-fluorocatechol. The kinetic data for 3-fluorocatechol could only be obtained in the presence of 2-mercaptoethanol. Besides inactivated enzyme, some 2-hydroxyhexa-2,4-diendioic acid was formed from 3-chlorocatechol, suggesting 5-chloroformyl-2-hydroxypenta-2,4-dienoic acid as the actual suicide product of meta-cleavage. A side product of 3-fluorocatechol cleavage is a yellow compound with the spectral characteristics of a 2-hydroxy-6-oxohexa-2,4-dienoic acid indicating 1,6-cleavage. Rates of inactivation by 3-fluorocatechol were reduced in the presence of superoxide dismutase, catalase, formate, and mannitol, which implies that superoxide anion, hydrogen peroxide, and hydroxyl radical exhibit additional inactivation.
336 citations
TL;DR: These results, taken together with previous findings, indicate that the DNA damage is produced by hydroxyl radicals formed when H2O2 reacts with chromatin-bound Fe2+ and that this damage is responsible for the killing effect.
Abstract: Phenanthroline, a strong iron chelator, prevents both the formation of DNA single-strand breaks and the killing of mouse cells produced by H2O2. These results, taken together with our previous findings, indicate that the DNA damage is produced by hydroxyl radicals formed when H2O2 reacts with chromatin-bound Fe2+ and that this damage is responsible for the killing effect.
325 citations
TL;DR: In this article, a reconstituted enzyme system containing alcohol-induced isozyme 3a of liver microsomal cytochrome P-450 was reported, in which the sum of acetaldehyde generated by the monooxygenation of ethanol and of hydrogen peroxide produced by the NADPH oxidase activity is inadequate to account for the O2 and NADPH consumed.
314 citations
TL;DR: It was determined that crocidolite, chrysotile, and amosite asbestos were all able to catalyze the generation of toxic hydroxyl radicals from a normal byproduct of tissue metabolism, hydrogen peroxide, indicating a major role for iron in the catalytic process, and suggesting a possible mechanism by which asbestos toxicity might be reduced.
300 citations
TL;DR: The results suggest that the photodynamic injury to the lens cation pump as well as to membrane lipids is incumbent upon an initial generation of superoxide and its derivatization to other oxidants, and the ocular lens is susceptible to oxidative insult and physiological damage through photocatalytic generation of various oxygen radicals.
Abstract: The mechanism of oxidative damage to the lens through intraocular photochemical generation of superoxide and its derivatization to other oxidants such as singlet oxygen, hydroxyl radical and hydrogen peroxide has been studied. Rat lenses when organ cultured aerobically in TC 199 containing additional amounts of riboflavin were damaged as demonstrated by an inhibition of the uptake of Rb 86 against a concentration gradient. The pump was not affected by light if the culture was conducted in the basal TC 199. However, light was observed to induce significant peroxidative degradation of the tissue lipids even in the basal medium, the degradation being indicated by the formation of malonaldehyde. Both the inhibition of the pump as well as the peroxidative degradation of the tissue lipids, were attenuated considerably by scavengers of superoxide and hydrogen peroxide. In addition, the lipid degradation was prevented by vitamins C and E. The results suggest that the photodynamic injury to the lens cation pump as well as to membrane lipids is incumbent upon an initial generation of superoxide and its derivatization to other oxidants. Thus, the ocular lens is susceptible to oxidative insult and physiological damage through photocatalytic generation of various oxygen radicals. Large concentrations of ascorbic acid in the aqueous humor seems to be able to provide significant protection against such an insult. Thus, this may be one of the functions of high concentration of ascorbic acid in the aqueous humor. The implication of oxidative stress has also been examined in the genesis of cataracts in vivo. Treatment with vitamin E of the Emory mouse led to a decrease in the rate of cataract progression suggesting that at least in some instances an oxidative stress could participate in the formation of cataracts. Oxygen radicals may inflict damage at multifarious biochemical sites. Human lens lipids were also shown to have an absorption maxima at 239 nm indicating their susceptibility to oxidative degradation. In addition the lipid extract has fluorescence similar to that of lipofuscins. The levels of MDA were higher in the brunescent cataracts as compared to that in the nonbrunescent cataracts. The implications of oxidative stress towards the genesis of cataracts in humans is being explored further.
01 Jan 1984
TL;DR: Nordblom and Coon as mentioned in this paper reported that, in a reconstituted enzyme system containing alcohol-induced isozyme 3a of liver microsomal cytochrome P-450, the sum of acetaldehyde generated by the monooxygenation of ethanol and of hydrogen peroxide produced by the NADPH oxidase activity is inadequate to account for the O2 and NADPH consumed.
Abstract: This laboratory has recently reported that, in a reconstituted enzyme system containing alcohol-induced isozyme 3a of liver microsomal cytochrome P-450, the sum of acetaldehyde generated by the monooxygenation of ethanol and of hydrogen peroxide produced by the NADPH oxidase activity is inadequate to account for the O2 and NADPH consumed. Studies on the stoichiometry have revealed the Occurrence of an additional reaction involving an overall 4-electron transfer to molecular oxygen which is presumed to yield water: 02 + 2 NADPH + 2H+ + 2 H20 + 2 NADP+. The occurrence of a peroxidase reaction in which free H202 is reduced to water by NADPH was ruled out. When the 4-electron oxidase activity is taken into account, measurements of NADPH oxidation and O2 consumption are in accord with the amounts of products formed in the presence of various P-450 isozymes, either in the absence or presence of typical substrates, including those which undergo hydroxylation, N- or 0-demethylation, or oxidation of hydroxymethyl to aldehyde groups. Of the substrates examined, some had no effect on the oxidase reaction yielding hydrogen peroxide or the 4-electron oxidase reaction, some were inhibitory, and some were stimulatory, but the same substrate did not necessarily have the same effect on the two reactions. Following the isolation of the phenobarbital-inducible form of rabbit P-450~~’ (2, 3), Nordblom and Coon (4) used this cytochrome and NADPH-cytochrome P-450 reductase, both free of catalase, to establish the stoichiometry of the reactions catalyzed. At saturating levels of several substrates, the initial rates of NADPH oxidation, O2 consumption, and product formation in the reconstituted enzyme system corresponded
TL;DR: Results are not consistent with a specific mechanism for cytochrome P-450-dependent ethanol oxidation but indicate that hydroxyl radicals, formed in an iron-catalyzed Haber-Weiss reaction and in a Fenton reaction, constitute the active oxygen species.
TL;DR: Inspecting of a wide range of carbonyl compounds showed that the monosaccharide moiety -CH(OH)-C- is conserved in carbonyL compounds reactive towards autoxidation, indicating that the ability to form an ene-diol is a prerequisite to monosACcharide Autoxidation.
TL;DR: The results have led us to propose that the thiol-dependent DNA cleavage reaction has two stages involving reduction of oxygen leading to hydrogen peroxide and then peroxide-dependentDNA cleavage.
Abstract: The 2:1 adriamycin-Fe(III) complex is able to bind to DNA and to catalyze its oxidative destruction. The binding of the drug-metal complex to DNA is indicated by characteristic spectral changes which are different from those seen with adriamycin intercalation and by the propensity of the drug-metal complex to precipitate DNA. Furthermore, intercalated adriamycin appears not to be available for iron binding. The resulting ternary complex is quite stable: it is not disrupted by incubation in the presence of EDTA and can be isolated by using Sephadex G-50 column chromatography. Disruption of the ternary complex requires vigorous conditions (extraction with phenol at 60 degrees C). The adriamycin-iron complex in free solution has the capacity to catalyze the reduction of oxygen by thiols. The DNA-bound drug-metal complex preserves this capacity over a wide range of complex/DNA ratios. As a consequence of this thiol-dependent oxygen reduction, DNA is cleaved. This thiol-dependent DNA cleavage has been shown to require hydrogen peroxide as an intermediate product. These results have led us to propose that the thiol-dependent DNA cleavage reaction has two stages involving (1) reduction of oxygen leading to hydrogen peroxide and then (2) peroxide-dependent DNA cleavage. An unusual property of this reaction is that the cleavage is not random but gives rise to a defined 2300 base pair fragment.
TL;DR: In the presence of oxygen, o-, m- and p-hydroxybenzoic acids are formed in the same isomeric distribution found for OH-radical attack on benzoic acid.
Abstract: Aqueous suspensions of titanium dioxide (anatase) containing benzoic acid or sodium benzoate have been illuminated with near-ultraviolet light under a variety of experimental conditions. In the presence of oxygen, o-, m- and p-hydroxybenzoic acids are formed in the same isomeric distribution found for OH-radical attack on benzoic acid. When OH-radical scavengers are present the yield of o-hydroxybenzoic acid is depressed. Ratios of rate constants evaluated on the basis of competition kinetics for the OH radical are in agreement with published rate constants. In the absence of oxygen the yield of the hydroxy compound is quite low, but high yields can be restored by the addition of iron(III). In oxygenated slurries, peroxides are formed in initial yield equivalent to about half the yield of total hydroxybenzoic acids. The addition of hydrogen peroxide to the slurries makes no significant difference to the yield of o-hydroxybenzoate. The results are consistent with the generation of OH radicals via the positive holes of the TiO2 particles, followed by OH-radical attack on the aromatic ring and subsequent oxidation of the hydroxy adduct with oxygen or iron(III) to give the corresponding phenol.
01 Jan 1984
TL;DR: The results indicate that taurine and other neutrophil amines protect neutrophils and other cells against oxidative attack by acting as a trap for HOCl and by competing with endogenous NH: for reaction with HOCl.
Abstract: Isolated human neutrophilic leukocytes were stimulated to produce hydrogen peroxide (H2OZ) and to secrete cytoplasmic granule components including myeloperoxidase into the medium. Myeloperoxidase catalyzed the oxidation of chloride (C1-) by H20z to yield hypochlorous acid (HOCl), which reacted with endogenous nitrogen compounds to yield derivatives containing nitrogen-chlorine (N-Cl) bonds. Compounds available for reaction with HOCl were ammonia (NH:), taurine, a-amino acids, and granule proteins and peptides that were released into the medium. A portion of the N-Cl derivatives formed under these conditions accumulated in the extracellular medium. These long lived oxidizing agents were characterized as hydrophilic, low molecular weight, mono-N-chloramine (RNHCl) derivatives based on their absorption spectrum, ability to oxidize 5-thio-2-nitrobenzoic acid and to chlorinate ammonia (NH:), and behavior upon ultrafiltration, gel chromatography, and extraction with organic solvents. The RNHCl derivatives were of low toxicity, but reacted with N&+ to yield the lipophilic oxidizing agent monoehloramine (NH2Cl). Therefore, the addition of NH: conferred bactericidal, cytotoxic, and cytolytic activities on the RNHCl derivatives. The results indicate that taurine and other neutrophil amines protect neutrophils and other cells against oxidative attack by acting as a trap for HOCl and by competing with endogenous NH: for reaction with HOCl. However, the RNHCl derivatives act as a reserve of oxidizing equivalents that is converted to a toxic form when an increase in NH: concentration favors formation of NH2Cl.
TL;DR: The generation of hydroxyl radical by adriamycin‐Fe3+ complex in the presence of DNA correlates with its ability to cleave DNA, andHydroxyl radicals are implicated as the reactive oxygen species involved in the DNA damage caused by the adri amycin‐ Fe3+complex.
TL;DR: The hydroxyl radical formation observed in active neutrophils during phagocytosis cannot be associated with lactoferrin activity and may be due to the presence of extraneous iron or an active protein impurity.
TL;DR: It is concluded that exogenously generated hydrogenperoxide or a hydrogen peroxide-derived product mediates rapid nonlytic release of PGI2 from cultured endothelial cells.
Abstract: We have examined the effect of activated neutrophils on the release of prostacyclin (PGI2) from cultured endothelial cells by radioimmunoassay and thin layer chromatography of its stable metabolite, 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha). Phorbol myristate acetate-activated neutrophils induced a time- and dose-dependent release of 6-keto-PGF1 alpha from human and bovine endothelial cell monolayers, whereas phorbol myristate acetate alone and neutrophils alone did not. Pretreatment of the endothelial cells with aspirin prevented neutrophil-mediated 6-keto-PGF1 alpha release, indicating that it did not depend upon neutrophil-generated endoperoxides. Phorbol myristate acetate-activated neutrophils from a patient with chronic granulomatous disease failed to induce endothelial 6-keto-PGF1 alpha release. Addition of catalase but not of superoxide dismutase significantly reduced human and bovine endothelial 6-keto-PGF1 alpha release by phorbol myristate acetate-activated neutrophils. Catalase-inhibitable endothelial 6-keto-PGF1 alpha release was also observed after the addition of the hydrogen peroxide-generating system, glucose-glucose oxidase, to bovine and human endothelial cell monolayers. Bovine endothelial 6-keto-PGF1 alpha release induced by exogenously generated hydrogen peroxide was attenuated by the phospholipase inhibitor mepacrine, suggesting that hydrogen peroxide may act by triggering endothelial membrane phospholipase activation. The release of 6-keto-PGF1 alpha by enzymatically or neutrophil-generated hydrogen peroxide was not associated with endothelial cell lysis as assessed by 51Cr release. We conclude that exogenously generated hydrogen peroxide or a hydrogen peroxide-derived product mediates rapid nonlytic release of PGI2 from cultured endothelial cells.
TL;DR: It is concluded that ceruloplasmin is an important protector against oxygen free radicals and H2O2.
Abstract: Oxygen free radicals are probably involved in the pathogenesis of rheumatoid arthritis (RA). The enzymes involved in protection against oxygen free radicals and H2O2 (superoxide dismutase, catalase, and glutathione peroxidase) were measured. Superoxide dismutase was not increased, glutathione peroxidase was slightly and catalase was strongly elevated in RA synovial fluid (SF) compared with control SF. Although these enzymes are present in SF, the activities are insufficient to protect against oxygen free radicals and H2O2. In contrast to transferrin, ferritin was increased in RA synovial fluid. Ceruloplasmin was also elevated. When rat liver microsomes were used as a target for oxygen free radicals, serum and SF were both protective. Gel filtration experiments showed that the fraction pattern in which there was maximal protective potential against lipid peroxidation corresponded closely to the level of ceruloplasmin. After removal of ceruloplasmin from serum or SF, about 70% of the protective capacity disappeared. It is concluded that ceruloplasmin is an important protector against oxygen free radicals.
TL;DR: In the presence of superoxide dismutase, the formation of this species was found to be inhibited, whereas that of Compound I was little affected, which suggests that this species is formed by the reaction of ferric catalase with O-2 and is probably the oxy form of this enzyme (Compound III).
TL;DR: Results imply a major difference in reactivity between free and enzymatically generated paraquat radicals, and suggest that the latter could react as an enzyme-paraquat radical complex, for which the relative rate of reaction with Fe3+ (chelate) compared with O2 is greater than is the case with free paraqu at radicals.
TL;DR: The results suggest that intact erythrocytes can scavenge H2O2, and as a result, protect the lung and possibly other tissues from damage.
Abstract: Addition of untreated or glutaraldehyde-fixed human erythrocytes decreased hydrogen peroxide (H2O2)-mediated acute edematous injury in isolated rat lungs, H2O2-induced damage to cultured bovine pulmonary artery endothelial cells, and H2O2-dependent oxidation of reduced cytochrome C in vitro. The results suggest that intact erythrocytes can scavenge H2O2, and as a result, protect the lung and possibly other tissues from damage.
TL;DR: When iron is complexed with EDTA, however, lipid peroxide decomposition is prevented, but the complex reacts with hydrogen peroxide to form OH.
TL;DR: In this paper, the peroxide in the presence of (NH4)6Mo7O24 · 4H2O and potassium carbonate is a chemoselective method to oxidize secondary alcohols to ketones, the latter also accelerated by cerium chloride.
TL;DR: The stimulatory effect of ferrous salts on the peroxidation of phospholipids can be enhanced by EDTA when the concentration of Fe2+ in the reaction is greater than that of EDTA.
Abstract: The stimulatory effect of ferrous salts on the peroxidation of phospholipids can be enhanced by EDTA when the concentration of Fe2+ in the reaction is greater than that of EDTA. Hydroxyl-radical scavengers do not inhibit peroxidation until the concentrations of Fe2+ and EDTA in the reaction are equal. Lipid peroxidation is then substantially initiated by hydroxyl radicals derived from a Fenton-type reaction requiring hydrogen peroxide. Superoxide radicals appear to play some role in the formation of initiating species.
TL;DR: The reaction between myeloperoxidase (donor:hydrogen-peroxide oxidoreductase, EC 1.11.7), hydrogen peroxide and ethyl hydroperoxide was investigated using the stopped-flow technique and it was concluded that hydrogenperoxide, cyanide, chloride and thiocyanate bind at the same site on the enzyme.
TL;DR: The results indicate that the mechanism whereby D-penicillamine in the presence of copper or ceruloplasmin inhibits T lymphocyte responsiveness involves the generation of hydrogen peroxide and that other neighboring cells likely to be found at chronic inflammatory sites, such as mononuclear phagocytes, contain enzymatic mechanisms to degrade hydrogenperoxide.
Abstract: It has been suggested that D-penicillamine is active in rheumatoid arthritis because of its capacity to function as a selective inhibitor of T lymphocyte function. The basis for the immunosuppressive action of this drug as well as mechanisms whereby the effect of D-penicillamine could be modified by elements of rheumatoid synovial tissue were examined. As previously reported, D-penicillamine, in the presence of copper ions markedly inhibited mitogen-induced human T lymphocyte DNA synthesis. Since the vast majority of copper in the body exists as an integral part of the ceruloplasmin molecule, the capacity of this cuproprotein to augment D-penicillamine-mediated inhibition of T cell function was examined. The requirement for copper ions could be entirely replaced by purified ceruloplasmin, which had been depleted of nonspecifically bound copper by passage over Chelex-100 columns. The mechanism by which D-penicillamine in the presence of either copper ions or ceruloplasmin caused inhibition of T lymphocyte responsiveness was examined. Partial protection from this inhibitory effect was accomplished by sodium borohydride. While superoxide dismutase had no protective effect, catalase was found to protect lymphocyte responsiveness totally from the inhibitory action of D-penicillamine and either copper ions or ceruloplasmin. Similarly, horseradish peroxidase and myeloperoxidase also protected responsiveness from these inhibitors while boiled catalase was without effect. These results indicate that inhibition of T lymphocyte responsiveness resulted from the generation of hydrogen peroxide. Since a number of cells likely to be present at chronic inflammatory sites, such as mononuclear phagocytes, contain enzymatic mechanisms to degrade hydrogen peroxide, the modulatory influence of these cells on the inhibition of T cell function caused by D-penicillamine and copper was examined. Monocytes, whose function was not suppressed by D-penicillamine and copper, were found to protect T lymphocyte responsiveness from the inhibitory effects of either the mixture of D-penicillamine and CuSO4 or of hydrogen peroxide. By contrast, endothelial cells, fibroblasts, or cells obtained from enzyme-digested noninflamed synovium could not protect T cells from the inhibitory effects of D-penicillamine and copper. Protection of T cells was afforded by means of a heat labile, azide-sensitive soluble factor present in lysates of human monocytes. These results indicate that the mechanism whereby D-penicillamine in the presence of copper or ceruloplasmin inhibits T lymphocyte responsiveness involves the generation of hydrogen peroxide and that other neighboring cells likely to be found w