Showing papers on "Hydrogen peroxide published in 1969"

Mechanism of the Electrochemical Reduction of Persulfates and Hydrogen Peroxide

Abstract: Electrochemical studies have shown that the reduction of persulfate and hydrogen peroxide is a two step mechanism, the first step occurs by electron transfer with the conduction band and the second step by hole injection with the valence band. It could be concluded from corresponding measurements performed with a semiconductor electrode that the electrochemical properties of these oxidizing agents have to be described by two instead of one redox (normal) potential. One normal potential is much lower and the other much larger than the theoretical value determined from thermodynamic data. These values are estimated as and .

Antifungal Effects of Peroxidase Systems

Abstract: In the presence of hydrogen peroxide and either potassium iodide, sodium chloride, or potassium bromide, purified human myeloperoxidase was rapidly lethal to several species of Candida. Its candidacidal activity was inhibited by cyanide, fluoride, and azide, and by heat inactivation of the enzyme. A hydrogen peroxidegenerating system consisting of d-amino acid oxidase, flavine-adenine dinucleotide, and d-alanine could replace hydrogen peroxide in the candidacidal system. Horseradish peroxidase and human eosinophil granules also exerted candidacidal activity in the presence of iodide and hydrogen peroxide; however, unlike myeloperoxidase or neutrophil granules, these peroxidase sources were inactive when chloride replaced iodide. Cells of Saccharomyces, Geotrichum, and Rhodotorula species, and spores of Aspergillus fumigatus and A. niger were also killed by the combination of myeloperoxidase, iodide, and hydrogen peroxide. Peroxidases, functionally linked to hydrogen peroxide-generating systems, could provide phagocytic cells with the ability to kill many fungal species.

Electron-spin-resonance evidence for enzymic reduction of oxygen to a free radical, the superoxide ion.

Abstract: 1. An electron-spin-resonance signal with g( parallel)2.08 and g( perpendicular)2.00 is observed by the rapid-freezing technique during the oxidation of substrates by molecular oxygen catalysed by xanthine oxidase at pH10. 2. The intensity of this signal is shown to depend on oxygen rather than on enzyme concentration, indicating that it is due to an oxygen free radical and not to the enzyme. 3. The same species is shown to be produced in the reaction at pH10 between hydrogen peroxide and periodate ions. Studies with this system have facilitated comparison of the properties of the oxygen radical with data in the literature on the products of pulse radiolysis of oxygenated water over a wide pH range. 4. It is concluded that the species observed is the superoxide ion, O(2) (-), and that the stability of this ion is greatly increased in alkaline solution. A mechanism explaining the alkaline stability is proposed. 5. The importance of O(2) (-) in the enzymic reaction is discussed.

Mechanism of peroxide-inactivation of the sulphydryl enzyme glyceraldehyde-3-phosphate dehydrogenase.

Abstract: The inactivation of glyceraldehyde-3-phosphate dehydrogenase by hydrogen peroxide has been investigated. The reaction obeyed two rate equations: (a) In the absence of catalysts (b) In the presence of catalysts These Kinetics are identical to those previously observed during glutathione oxidation by peroxides. Enzyme inactivation was shown to be strictly related to sulphydryl group modification and this modification can account for the inactivation. For total inactivation H2O2, like iodoacetate, modified about 3.5 sulphydryl groups in the enzyme. o-Iodosobenzoate, however, modified approximately 8.5 sulphydryl groups and it was concluded that H2O2, unlike o-iodosobenzoate, did not oxidize the “essential” sulphydryl groups of the enzyme to disulphide, but to sulphenic acid residues. Peroxide-inactivated glyceraldehyde-3-phosphate dehydrogenase could be fully reactivated and sulphydryl oxidation fully reversed if the enzyme was treated immediately with excess small thiol. The reversibility of inactivation decreased progressively if thiol treatment was delayed. 4 hours after peroxide treatment, neither enzyme inactivation nor sulphydryl oxidation could be reversed.

Killing and Lysis of Gram-negative Bacteria Through the Synergistic Effect of Hydrogen Peroxide, Ascorbic Acid, and Lysozyme

Abstract: A mixture of hydrogen peroxide and ascorbic acid has been found to generate an antibacterial mechanism which is active against gram-negative bacteria. It results in bacterial death and renders the organism sensitive to lysis by lysozyme. Under the conditions used, horseradish peroxidase did not augment the antibacterial effect. It is suggested that the effector mechanism involves the generation of short-lived free radicals which disturb the integrity of the cell wall. This effect alone might kill bacteria by interfering with selective permeability, but in the presence of lysozyme a further bactericidal activity is accomplished by complete disruption of the cell. It is proposed that a transient antibacterial system such as that described could exist within phagocytic cells. Free radicals would be formed through the interaction of certain oxidizable substances and hydrogen peroxide, which is produced during the enhanced metabolic activity that accompanies ingestion of bacteria. Such a system would help to explain why macrophages, which are apparently devoid of preformed bactericidins, are nonetheless very efficient in killing most phagocytosed bacteria.

Leukocyte bactericidal activity in chronic granulomatous disease: correlation of bacterial hydrogen peroxide production and susceptibility to intracellular killing.

Abstract: Susceptibility of bacteria to intracellular killing by polymorphonuclear leukocytes from a patient with chronic granulomatous disease could be correlated with bacterial hydrogen peroxide production.

Enzymatic oxidation of bilirubin.

Abstract: The following agents were found to oxidize bilirubin in vitro: hemoglobin and horse-radish peroxidase (both with hydrogen peroxide), cytochrome c, xanthine oxidase, and an insoluble oxidase, present in brain and other tissues. Kinetic constants were determined. The process with hemoglobin was inhibited competitively by two product molecules. The insoluble oxidase from brain was present in mitochondria. The supernatant fraction contained an inhibitor. The oxidase was inactive in the absence of salt and was unspecifically activated by a number of salts, the activity depending upon ionic strength, irrespective of which ions were present. Reaction products included biliverdin and a yellow, diazo-negative, polar pigment with the same oxidation level as bilirubin.

Catalase-Aminotriazole Method for Measuring Secretion of Hydrogen Peroxide by Microorganisms

Abstract: A new method for measuring the secretion of H(2)O(2) has been based upon an H(2)O(2)-dependent inhibition of catalase by 3-amino-1,2,4-triazole. The conversion of an H(2)O(2)-secretion rate into a catalase inhibition rate amplified a relatively small molar concentration of H(2)O(2) and provided a highly specific and sensitive method for quantitatively measuring H(2)O(2). A major advantage of this approach is that it does not require extensive accumulation of H(2)O(2) in the environment. The method was successfully employed to measure H(2)O(2) secretion by Mycoplasma pneumoniae, which possesses a peroxidase-like activity that limits the accumulation of H(2)O(2) in the environment.

Antistreptococcal Activity of Lactoperoxidase

Abstract: A study of the inhibition of the growth of Streptococcus cremoris 972 by the enzyme lactoperoxidase has shown, in agreement with previous investigations, that the inhibition requires a source of both peroxide and thiocyanate. The thiocyanate may play more than one role. It stabilizes the very dilute solutions of lactoperoxidase employed in these studies, and its oxidation products may be involved in the inhibition. Binding of the enzyme by the microorganism is suggested by the fact that when the organism was preincubated with the enzyme and then in a medium free from the enzyme, but containing peroxide and thiocyanate, the growth of the organism was inhibited. This inhibition has all the properties of the enzyme-containing system. Although no dialyzable factor could be demonstrated to cause the inhibition, the inhibitory state involving peroxide, the enzyme, and thiocyanate survived for at least 60 min before cells were added to the medium. When catalase was present in the medium prior to the addition of the cells, the inhibition was completely reversed. It was only partially reversed if catalase was added a few moments after the addition of the cells. The data have been interpreted as indicating that the inhibition takes place rapidly and requires the formation of a quaternary complex of the cells, thiocyanate, peroxide, and the enzyme lactoperoxidase.

The transport of oxidized glutathione from the erythrocytes of various species in the presence of chromate.

Abstract: 1 Erythrocytes from normal and glucose 6-phosphate dehydrogenase-deficient humans were subjected to hydrogen peroxide diffusion to oxidize the GSH Studies were carried out in the presence and absence of chromate to inhibit glutathione reductase and with or without the addition of glucose 2 The GSH content of erythrocytes from other species was oxidized by subjecting them to hydrogen peroxide diffusion in the presence of chromate and glucose 3 Chromate (1·3mm) inhibited glutathione reductase by about 80%, whereas glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, hexokinase, phosphofructokinase and pyruvate kinase were not inhibited 4 The GSSG formed was transported from the erythrocytes to the medium 5 The transport rate of GSSG from glucose 6-phosphate dehydrogenase-deficient erythrocytes subjected to hydrogen peroxide diffusion in the presence of chromate was comparable with that from normal and glucose 6-phosphate dehydrogenase-deficient erythrocytes 6 The rate of transport of GSSG from erythrocytes of various species studied could be ranked: pigeon>rabbit>rat>donkey>man>dog>horse>sheep>chicken>fish

Role of the intracellular distribution of hepatic catalase in the peroxidative oxidation of methanol

Abstract: Previous to 1950, when Bonnichsenl isolated crystalline alcohol dehydrogenase (ADH) and showed that it did not react with methanol,$ it was believed that the ADH system was responsible for the oxidation of all primary aliphatic alcohols, including methanol (FIGURE 1 ) . This observation redirected attention to the peroxidative system as a means of oxidizing methanol. As early as 1936, Keilin and Hartree3 showed that catalase catalyzed the oxidation of alcohols to their aldehydes when hydrogen peroxide was supplied in low concentrations, as might be provided in living cells through the action of flavin and other peroxide-generating enzymes. They presented arguments to support their view that catalase is not present in the tissues to protect against peroxide intoxication, as was widely contended, but rather to carry out coupled (peroxidative) oxidations. Employing techniques that permitted very rapid spectral determinations, Chance4 identified the intermediate complexes and analyzed the kinetics of the components of the reaction (FIGURE 1 ) . Ideas were exchanged for several years as to whether or not the peroxidative system participated in the in vivo oxidation of methanol and other alcohols. A direct means of examining the question was provided when Heim and coworkers5 showed that the intraperitoneal injection of 3-amino-1,2,4-triazole (AT) caused a reduction in hepatic and renal catalase activities of 90% or more. Mannering and Parkss found that the AT-induced inhibition of hepatic catalase was accompanied by a 70% reduction of the methanol-oxidizing capacity of rat liver homogenates. The addition of crystalline beef liver catalase to these homogenates restored methanol oxidation to normal. While these in vitro studies pointed to a role of catalase in methanol oxidation, they did little to establish its participation in vivo. Because of the complexity of the system, involving as it does the rate of formation of hydrogen peroxide, which in turn depends upon the concentration of substrates available to the peroxide-generating enzymes as well as the availability of hepatic catalase to the hydrogen peroxide produced by these enzymes, it seemed unlikely that in vitro studies would provide much information as to what was occurring in the intact animal. This presentation is devoted largely to a review of the evidence that shows that the intact rat oxidizes methanol largely through the peroxidative system, but that ethanol oxidation proceeds differently, probably almost entirely via the ADH system. The evidence is based on in vitro studies that employed several approaches: 1 ) 14C-methanol and 1 -Wethano1 oxidation were studied

Lysis of Bacterial Spores with Hydrogen Peroxide

Abstract: Summary Spores of Bacillus cereus were made sensitive to lysis with H2O2 by treatment with reagents which break disulphide bonds (e.g. thioglycollic acid), by incubation with reagents which break hydrogen bonds (e.g. urea and lithium bromide) or by incubation at high temperatures. However, treated spores lost viability in the presence of H2O2 at the same rate as did untreated spores. Lysis was optimal at high pH values and in the presence of metal ions, e.g. Cu2+, suggesting that lysis was caused by free radicals formed by metal catalysed decomposition of the peroxide. Isolated spore coats, in contrast to whole spores, were lysed by H2O2 even when not pretreated. and the immediate products of spore coat lysis were soluble proteins; on continued incubation with H2O2 these proteins were degraded to low MW peptides and amino acids. It appeared that whole spores resisted lysis because peroxide sensitive bonds were masked by compact tertiary molecular structures, and that the sensitizing agents were able to loosen these structures sufficiently to expose bonds sensitive to H2O2.

Formation of a histidine-peroxide adduct by H2O2 or ionizing radiation on histidine: chemical and microbiological properties.

Abstract: We find that small amounts of hydrogen peroxide in the presence of histidine strongly inhibit the growth of Salmonella typhimurium in glucose medium (pH 70). Other amino acids and analogues, e.g. imidazole, alanine, and histamine, are relatively or completely inactive under the same conditions. We also find that gamma-irradiated oxygenated solutions of histidine inhibit bacterial growth to an extent proportional to the amount of H2 0 2 produced radiolytically. In the glucose-containing microbiological growth medium (pH 70, t = 37°c), the presence of histidine greatly retards the normal rate of disappearance of added H202. These and other chemical and microbiological observations reported here suggest that histidine and H202 readily form a stable adduct. A histidine-peroxide crystalline adduct has been prepared and chemically characterized (Dirscherl and Mosebach 1954). Subsequently the preparation of other amino-acid-peroxide adducts has been described (Dirscherl and Moersler 1964).

The meso-reactivity of porphyrins and related compounds. Part IV. Introduction of oxygen functions

Abstract: Treatment of octaethylporphyrin with hydrogen peroxide in concentrated sulphuric acid in the cold gives a monoxy-derivative: the earlier structures advanced for this type of compound are disproved, and this particular example is formulated as 2,3,7,8,12,13,18,18-octaethyl-17-oxochlorin. By-products are observed, one of which is formulated as a dioxo-b-tetrahydroporphyrin.Benzoyl peroxide reacts with octaethylporphyrin in 1,2,4-trichlorobenzene at 95° to give 5-benzoyloxy-octaethylporphyrin. Hydrolysis of this gives octaethyloxophlorin, aspects of the chemistry of which are discussed. The location of the oxygen function at the meso-position is confirmed by ring synthesis.

Destruction of cyanide in aqueous solutions

Abstract: A process for the destruction of cyanide anions in aqueous solutions is provided using hydrogen peroxide and a soluble metal compound catalyst such as a soluble copper compound to increase the reaction rate. An aqueous composition containing hydrogen peroxide and the catalyst is also provided which can be added directly to the cyanide solution. The pH of the cyanide solution to be treated is adjusted with acid or base to a pH of about 8.3 to 11, the soluble metal compound catalyst is added at a level to give about 5 to 1,000 p.p.m. of catalyst, the hydrogen peroxide is added to give a molar ratio of hydrogen peroxide to cyanide anions of at least about 0.8 and the temperature of the solution is maintained within the range of about 20* to 75* C.

Hydroxylation of aromatic compounds

Abstract: Nuclear hydroxylation of aromatic compounds is effected by treating said aromatic compounds with hydrogen peroxide in the presence of a catalyst comprising an alkaline solution containing a salt of hydrocyanic acid, or an aromatic or aliphatic nitrile compound.

Light microscopic study of the peroxidatic activity of catalase in formaldehyde-fixed rat liver.

Abstract: The peroxidatic activity of rat liver catalase was demonstrated by histochemical staining with 3,3'-diaminobenzidine as hydrogen donor. The activity was so weak that its location was hard to identify in formaldehyde-fixed cells, although high catalatic activity was present, as evidenced by the production of bubbles upon the addition of hydrogen peroxide to the incubation medium. Pretreatment of fixed sections for 60 min at 37°C with formamide, urea or trypsin enhanced the peroxidatic activity significantly. The reaction granules scattered throughout the cytoplasm of the parenchymal cells probably correspond to the peroxisomes.

Process for reducing the viscosity of a cellulose ether with hydrogen peroxide

Abstract: A CONTROLLED REDUCTION OF THE VISCOSITY OF A CELLULOSE ETHER IS ACHIEVED BY BLENDING AN ESSENTIALLY DRY, FREEFOWING PARTICULATE CELLULOSE ETHER WITH A PREDETERMINED AMOUNT OF HYDROGEN PEROXIDE, HEATING THE BLENDED CELLULOSE ETHER AT ABOUT 50*-150*C. TO REACT SUBSTANTIALLY ALL THE ADDED HYDROGEN PEROXIDE, AND RECOVERING A LOWER VISCOSITY, PARTICULATE CELLULOSE ETHER HAVING AN INTRINSIC FLUIDITY GREATER THAN THE INITIAL CELLULOSE ETHER. HIGH YIELDS AND A READILY CONTROLLED VISCOSITY REDUCTION AE OBTAINED.

Glucose-dependent secretion and destruction of hydrogen peroxide by Mycoplasma pneumoniae.

Abstract: The secretion of H(2)O(2) by Mycoplasma pneumoniae and M. gallisepticum was measured with the new catalase-aminotriazole method. Peroxide secretion by the mycoplasmas was stimulated by glucose. When catalase and aminotriazole were omitted and exogenous H(2)O(2) was added to the mycoplasmas, a loss in H(2)O(2) was noted with time; the addition of glucose speeded the disappearance of H(2)O(2). The presence of this peroxidase-like activity in the mycoplasmas explains an observed failure of H(2)O(2) to accumulate freely in the suspension medium.

Stabilization of acidified hydrogen peroxide solutions

Abstract: Metal cleaning and pickling solutions containing acidified hydrogen peroxide and ions of the metal being etched are stabilized against decomposition of the hydrogen peroxide at elevated temperatures by the addition of an organic hydroxy compound of the class consisting of phenol, paramethoxy phenol, allyl alcohol, crotyl alcohol, and cis-1,4-but-2-ene-diol.

Vacuum‐Ultraviolet Photochemistry. IX. Primary and Chain Processes in the Photolysis of Hydrogen Peroxide

Abstract: Primary processes leading to atomic and molecular hydrogen formation in hydrogen peroxide photolysis at 1236 A, noting OH formation

Hydroxylation. Part IV. Oxidation of some benzenoid compounds by Fenton's reagent and the ultraviolet irradiation of hydrogen peroxide

Abstract: The pH of the solution has a marked effect on the relative amounts of the various products formed by the oxidation of benzene, toluene, or anisole by Fenton's reagent; for example, as the pH is lowered, toluene gives an increased proportion of bibenzyl compared with the cresols, while benzene gives an increased proportion of phenol compared with biphenyl. At pH 2·5, both the yields and the distribution of the methoxyphenols from the oxidation of anisole are strongly dependent on the presence of oxidants other than the hydroxyl radical. The bases of these effects are discussed in the light of these and other observations, and particular attention is drawn to the importance of the one-electron oxidation of (substituted) hydroxycyclohexadienyl radicals, as compared with alternative reaction paths for these species, in determining the yield of each phenol.