Showing papers on "Hydrogen peroxide published in 1976"

Role of ubiquinone in the mitochondrial generation of hydrogen peroxide

Abstract: Antimycin-inhibited bovine heart submitochondrial particles generate O2- and H2O2 with succinate as electron donor. H2O2 generation involves the action of the mitochondrial superoxide dismutase, in accordance with the McCord & Fridovich [(1969) j. biol. Chem. 244, 6049-6055] reaction mechanism. Removal of ubiquinone by acetone treatment decreases the ability of mitochondrial preparations to generate O2- and H2O2, whereas supplementation of the depleted membranes with ubiquinone enhances the peroxide-generating activity in the reconstituted membranes. Addition of superoxide dismutase to ubiquinone-reconstituted membranes is essential in order to obtain maximal rates of H2O2 generation since the acetone treatment of the membranes apparently inactivates (or removes) the mitochondrial superoxide dismutase. Parallel measurements of H2O2 production, succinate dehydrogenase and succinate-cytochrome c reductase activities show that peroxide generation by ubiquinone-supplemented membranes is a monotonous function of the reducible ubiquinone content, whereas the other two measured activities reach saturation at relatively low concentrations of reducible quinone. Alkaline treatment of submitochondrial particles causes a significant decrease in succinate dehydrogenase activity and succinate-dependent H2O2 production, which contrasts with the increase of peroxide production by the same particles with NADH as electron donor. Solubilized succinate dehydrogenase generates H2O2 at a much lower rate than the parent submitochondrial particles. It is postulated that ubisemiquinone (and ubiquinol) are chiefly responsible for the succinate-dependent peroxide production by the mitochondrial inner membrane.

Formation of hydrogen peroxide by isolated cell walls from horseradish (Armoracia lapathifolia Gilib.).

Abstract: Isolated cell-wall suspensions from horseradish in the presence of 5×10(-4) M MnCl2 catalyze the production of hydrogen peroxide at the expense of either NADPH or NADH. This reaction is inhibited by scavengers of the superoxide free radical ion such as ascorbate or dihydroxyphenols or by superoxide dismutase, and stimulated by monophenols such as p-coumaric acid. On comparison with isolated (commercial) horseradish peroxidase it becomes evident that (a) cell-wall-bound peroxidase(s) is (are) responsible for the production of hydrogenperoxide, involving the superoxide free radical ion as an intermediate of the complex reaction chain.

The oxidation of phenylhydrazine: superoxide and mechanism.

Abstract: The oxidation of phenylhydrazine in buffered aqueous solutions is a complex process involving several intermediates. It can be initiated by metal cations, such as Cu2+; in which case EDTA acts as an inhibitor. It can also be intiated by oxyhemoglobin; in which case chelating agents do not interfere. Superoxide radical is both a product of this reaction and a chain propagator. The formation of O2- could be demonstrated in terms of a reduction of nitroblue tetrazolium, which was prevented by superoxide dismutase. The importance of O2- in carrying the reaction chains was shown by the inhibition of phenylhydrazine oxidation by superoxide dismutase. Hydrogen peroxide accumulated during the reaction and could be detected with catalase. The progress of this oxidation could be monitored in terms of oxygen consumption and by following increases in absorbance at 280 or 320 nm. The oxidation was markedly autocatalytic and superoxide dismutase had the effect of extending the lag period. The absorbance at 280 nm was due to an intermediate which first accumulated and was then consumed. This intermediate appears to be benzendiazonium ion. The absorbance at 320 nm was due to a stable product, which was not identified. The time course of oxygen consumption paralleled the increase in absorbance at 320 nm and lagged behind the changes at 280 nm. Exogenous benzenediazonium ion accelerated the oxidation of phenylhydrazine and eliminated the lag phase. Benzenediazonium ion must therefore react with phenylhydrazine to produce a very reactive intermediate, possibly phenyldiazene. A mechanism was proposed which is consistent with the data. The intermediates and products of the oxidation of phenylhydrazine include superoxide radical, hydrogen peroxide, phenylhydrazyl radical, phenyldiazene, and benzenediazonium ion. This is a minimal list: others remain to be detected and identified. It appears likely that the diverse biological effects of phenylhydrazine are largely due to the reactivities of these intermediates and products.

Characterization of a cell-lethal product from the photooxidation of tryptophan: hydrogen peroxide

Abstract: Near-ultraviolet (300 to 400 nanometers) irradiation of saturated, oxygenated solutions of tryptophan in the absence of added sensitizer gives rise to substances that have various biological effects on isolated cells, including mutagenicity and selective lethality to recombination-deficient bacterial mutants. One of these biologically active products has been identified as H2O2, on the basis of spectrometric, chromatographic, chemical, and biological properties. Now H2O2 has been shown to account for the biological activities mentioned above.

The mechanism of the degradation of DNA by streptonigrin.

Abstract: The production of single strand cleavage in covalently-closed circular-DNA by the antitumour agent streptonigrin (reduced in situ by NADH) is demonstrated using the ethidium bromide fluorescence assay described previously. The degradation dependent on oxygen is completely inhibited by superoxide dismutase (EC 1.15.1.1) suggesting the intermediacy of the superoxide radical anion in the degradation. However similar complete inhibition of DNA strand breakage by catalase (EC 1.11.1.6) indicates that the hydroxyl radical (formed by interaction of superoxide with hydrogen peroxide) is the primary reactive species. Cupric ion stimulates the cleavage reaction and cobaltous ion has no effect in keeping with model studies using quinolinequinones.

The effect of ultrasound on water in the presence of dissolved gases

Abstract: Sonolysis of water at 447 kHz causes a decrease in the pH. The products formed depend to some extent on the nature of the dissolved gases; products observed are hydrogen peroxide, nitrous and nitri...

Catalase: its effect on microbial enumeration.

Abstract: The addition of catalase to the surface of selective medium plates permitted increased enumeration of physically or chemically injured (stressed) microorganisms. Catalase acted by preventing the accumulation of hydrogen peroxide in, or around, injured cells. Heat-injured Staphylococcus aureus cells had decreased catalase activity, and heat-inactivated catalase had no effect on enumeration.

A comparison of the metabolic response to phagocytosis in human granulocytes and monocytes.

Abstract: Recent studies indicate that oxygen radicals such as superoxide or singlet oxygen may be important in the functional activity of human granulocytes. We have examined the possible importance of these radicals in the functional capacity of human blood monocytes. Monocytes, like granulocytes, generate chemiluminescence during phagocytosis. Chemiluminescence is impaired 50-90% by superoxide dismutase, an enzyme which enhances the dismutation of superoxide to hydrogen peroxide. These results indicate that superoxide is related to the chemiluminescence generated by monocytes. Superoxide dismutase in a concentration which impaired chemiluminescence also impaired the staphylococcal killing by monocytes. Hexose monophosphate shunt activity and hydrogen peroxide production by granulocytes and monocytes were also evaluated. The oxidation of [1-14C]glucose was used as a measure of hexose monophosphate shunt activity and the oxidation of [14C]formate as an estimation of hydrogen peroxide production. The oxidation of both substrates by monocytes was increased during phagocytosis but, in contrast to results in granulocytes, was not further increased by the addition of superoxide dismutase. These data indicate that superoxide may be important in bactericidal activity of human monocytes. Our results also suggest that the metabolism of oxygen radicals in monocytes and granulocytes may be different.

Nonspecific bactericidal activity of the lactoperoxidases-thiocyanate-hydrogen peroxide system of milk against Escherichia coli and some gram-negative pathogens.

Abstract: Two strains of Escherichia coli and one strain each of Salmonella typhimurium and Pseudomonas aeruginosa were killed by the bactericidal activity of the lactoperoxidase-thiocyanate-hydrogen peroxide system in milk and in a synthetic medium. H2O2 was supplied exogenously by glucose oxidase, and glucose was produced at a level which was itself noninhibitory. Two phases were distinguished: the first phase was dependent on the oxidation of SCN(-) by lactoperoxidase and H2O2, which was reversed by reducing agent, and the second phase was dependent on the presence of accumulated H2O2, which was reversed by catalase. The latter enzyme could also reverse the first phase, but only when present in excessive and unphysiological levels. The bactericidal activity was greatest at pH 5 and below, and it depended on the SCN(-)concentration and on the number of organisms. Since raw or heated milk neutralizes the acid barrier against infection in the stomach, the bactericidal system discussed may contribute to the prevention of enteric infections in neonates.

Polarographic analysis of cholesterol and other macromolecular substances

Abstract: A micro-method for measurement of sterols such as cholesterol, and other macromolecular substances, is disclosed utilizing enzymes for the conversion of such substances to produce ultimately hydrogen peroxide and measurement of the generated hydrogen peroxide with a membrane covered polarographic anode. The polarographic anode is set at a voltage so as to produce current proportional to hydrogen peroxide concentration. According to the method of this invention, the macromolecular substance under analysis enters into an enzymatic reaction in a sample chamber on the side of the membrane opposite the anode and the membrane is impermeable to such substances, but senses hydrogen peroxide. The method is adapted to measure free and total blood cholesterol in a precise, rapid, sensitive and specific manner. Other substances of a macromolecular or conventional membrane impermeable nature such as high molecular weight starches or proteins, which undergo enzymatic reaction to produce ultimately hydrogen peroxide, may be analyzed by employing this polarographic technique.

Compositions for the detection of hydrogen peroxide

Abstract: There are disclosed buffered compositions for detecting either hydrogen peroxide or a substance having peroxidative activity by the catalytic oxidation of a dye-providing material by hydrogen peroxide in the presence of the material having peroxidative activity, which compositions comprise (A) hydrogen peroxide or substance having peroxidative activity, as appropriate, and (B) as the dye-providing material, either (I) a mixture of (a) either a sulfonyl hydrazone of the formula ##STR1## or a sulfonyl hydrazone precursor of the formula ##STR2## wherein R = alkyl R' = hydrogen, aryl, alkoxy, halogen or alkyl R" = aryl or alkyl Z = atoms necessary to complete a heterocyclic ring of 5-6 atoms in the ring nucleus M⊖ = an anion; and (b) a coupler or (II) a triarylimidazole of the formula ##STR3## wherein R 1 , R 2 and R 3 are each an organic group such that at least one of R 1 , R 2 and R 3 is an ortho or para hydroxy substituted aryl group of up to 18 carbon atoms; the other two R 1 , R 2 and R 3 being chosen such that the oxidation potential of the imidazole lies between -70 mV to +110 mV measured by cyclic voltometry against a standard calomel electrode using a carbon based electrode The method of utilizing such compositions and multilayer elements incorporating the same for the analysis of fluids suspected of containing hydrogen peroxide, substances having peroxidative activity or other analytes which produce hydrogen peroxide in their analysis are also described

Near-uv-induced breaks in phage dna: sensitization by hydrogen peroxide (a tryptophan photoproduct)

Abstract: — Near-UV irradiation of l-tryptophan yields a large number of photoproducts. When this mixture is added to recombinationless (rec) mutants of bacteria, the cells are killed. The most toxic component of tryptophan photoproducts has been identified as hydrogen peroxide (H2O2). We now report that both tryptophan photoproducts and H2O2 sensitize phage DNA to near-UV radiation resulting in enhanced killing as well as enhanced DNA breakages. We conclude that the in situ production of H2O2 via tryptophan photolysis may be an important biological event.

Photocatalytic oxidation of propan-2-ol in the liquid phase by rutile

Abstract: The photocatalytic oxidation of liquid propan-2-ol to acetone has been investigated using irradiated suspensions of pure rutile. It is shown that ultraviolet radiation, rutile and a source of oxygen are all necessary for measurable reaction to occur at 310 K. The parameters controlling the photoactivity of pure rutile, together with effects of adding hydrogen peroxide, water or dissolved salts to the reaction mixture, have been investigated. Supporting measurements with doped rutile and less pure anatase have also been made.The experimental results, which include values of the quantum yield, do not support a chain mechanism for acetone formation. Mechanisms are proposed, in which reactive species are formed by the surface trapping of both photoelectrons and photoholes.

Stable viscous hydrogen peroxide solutions containing a surfactant and a method of preparing the same

Abstract: A stable viscous liquid bleach that may be safely applied directly to stubborn stains is prepared by adding certain anionic or nonionic surfactants to aqueous solutions containing up to 30% by weight hydrogen peroxide. The viscosity of the aqueous hydrogen peroxide solution is adjusted to be within the range of about 60 cps - 6,000 cps by addition of a water dispersible copolymer of an alpha-beta monoolefinically unsaturated lower aliphatic carboxylic acid crosslinked with a polyether of a polyol selected from the class consisting of oligo saccharides, reduced derivatives thereof in which the carbonyl group is converted to an alcohol group and pentaerythritol, the hydroxy groups of said polyol which are modified being etherified with allyl groups, said polyol having at least two allyl groups per polyol molecule.

The effect of hydrogen peroxide on spores of Clostridium bifermentans.

Abstract: SUMMARY: The effect of hydrogen peroxide on the germination, colony formation and structure of spores of Clostridium bifermentans was examined. Treatment with 0·35 M-hydrogen peroxide increased the germination rate at 25° but increasing the temperature or concentration of hydrogen peroxide decreased both the germination rate and colony formation. The presence of Cu2+ increased the lethal effect of hydrogen peroxide on colony formation as much as 3000-fold. Pre-incubation of spores with Cu2+ before treatment with hydrogen peroxide produced a similar increase, but this could be eliminated by washing the spores with dilute acid or ethylenediamine tetraacetate. Hydrogen peroxide removed protein from spores—apparently from the coat—and treatment with dithiothreitol, which also removes spore-coat protein, increased the lethal effect of hydrogen peroxide 500-fold, suggesting that spore-coat protein has a protective effect against hydrogen peroxide.

Hydrogen peroxide production and the release of carbon dioxide during glycollate oxidation in leaf peroxisomes.

Abstract: The rate at which H2O2 becomes available during glycollate oxidation for further oxidation reactions, especially that of glyoxylate to formate and CO2, in peroxisomes from spinach-beet (Beta vulgaris L., var. vulgaris) leaves has been determined by measuring O2 uptake in the presence and absence of added catalase. The rates observed under air and pure O2 were sufficient to account for the 14CO2 released from [l-14C]glycollate under these conditions; the two reactions showed similar characteristics. In the course of the reaction, a fall in catalase activity was observed concomitant with an increase in 14CO2 release. There is no evidence that catalase was disproportionately lost from the peroxisomes during isolation, and it is argued that the CO2 release observed contributes to the photorespiratory CO2 loss in intact leaves.