Showing papers on "Hydrogen peroxide published in 1968"
TL;DR: Myeloperoxidase, at high concentrations, exerted an antibacterial effect on L. acidophilus in the absence of added halide, which also was temperature- and catalase-sensitive, and suggests that, under the conditions employed, the antibacterial properties of a weak acid extract of guinea pig leukocytes is due, in part, to its peroxid enzyme content, particularly if a halide is present in the reaction mixture.
Abstract: An antibacterial effect of myeloperoxidase, a halide, such as iodide, bromide, or chloride ion, and H2O2 on Escherichia coli or Lactobacillus acidophilus is described. When L. acidophilus was employed, the addition of H2O2 was not required; however, the protective effect of catalase suggested that, in this instance, H2O2 was generated by the organisms. The antibacterial effect was largely prevented by preheating the myeloperoxidase at 80 C or greater for 10 min or by the addition of a number of inhibitors; it was most active at the most acid pH employed (5.0). Lactoperoxidase was considerably less effective than was myeloperoxidase when chloride was the halide employed. Myeloperoxidase, at high concentrations, exerted an antibacterial effect on L. acidophilus in the absence of added halide, which also was temperature- and catalase-sensitive. Peroxidase was extracted from intact guinea pig leukocytes by weak acid, and the extract with peroxidase activity had antibacterial properties which were similar, in many respects, to those of the purified preparation of myeloperoxidase. Under appropriate conditions, the antibacterial effect was increased by halides and by H2O2 and was decreased by catalase, as well as by cyanide, azide, Tapazole, and thiosulfate. This suggests that, under the conditions employed, the antibacterial properties of a weak acid extract of guinea pig leukocytes is due, in part, to its peroxidase content, particularly if a halide is present in the reaction mixture. A heat-stable antibacterial agent or agents also appear to be present in the extract.
819 citations
TL;DR: Culture filtrates of Lactobacillus lactis and LactOBacillus bulgaricus were observed to contain material inhibitory against Staphylococcus aureus, and the inhibitory factor was identified as hydrogen peroxide.
213 citations
TL;DR: The chemical reactions between DNA and H2O2 or NH2OH, which at low concentration and in the presence of oxygen produces H2 O2, have been investigated using DNA and oligodeoxyadenylic acid.
208 citations
192 citations
190 citations
TL;DR: Myeloperoxidase was isolated from leucocytes obtained from the blood of patients suffering from chronic granulocytic leukaemia and was homogeneous in ultracentrifuge and free boundary electrophoresis.
Abstract: Myeloperoxidase was isolated from leucocytes obtained from the blood of patients suffering from chronic granulocytic leukaemia. The enzyme was purified 850 fold and was homogeneous in ultracentrifuge and free boundary electrophoresis. The molecular weight of the enzyme was found to be about 160,000.
The enzyme forms a spectrally characteristic complex with hydrogen peroxide with absorption maximum at 458 mμ. The spectrum of the native enzyme has absorption maxima at 430 and 570 mμ. The reduced enzyme is characterized by a spectrum with absorption maxima at 472 and 637 mμ.
The investigated myeloperoxidase catalysed oxidation of amino acids by hydrogen peroxide. Products of the oxidation of amino acids were ammonia, carbon dioxide, and an aldehyde corresponding to the oxidized amino acid. The observed reaction of deamination and decarboxylation is activated by chloride ions. In the presence of the chloride ions the optimum of the reaction is shifted toward the higher pH values.
The velocity of the reaction was found to be dependent on the concentration of the amino acid studied. Km values for various amino acids increased in the range 3.4 × 10−4 to 10−3 M in proportion to rising hydrophobic properties of the substrates. Taurine was found to be a competitive inhibitor in the examined reaction, and Ki values were in the range of 2 to 3 × 10−4 M, for different amino acids.
154 citations
TL;DR: Cholesterol was the most effective inhibitor, followed by beta-sitosterol and stigmasterol; and at the same concentration, the sterols were more effective than CaCl(2), the classic membrane stabilizer.
Abstract: Alcohols and hydrogen peroxide altered the permeability of membranes of Beta vulgaris root cells. Generally alcohols increased the permeability of membranes without going through an induction period except methanol which required a 10- to 15-hour induction period. The membrane effect of methanol could be inhibited with CaCl(2), cholesterol, beta-sitosterol, and stigmasterol. Cholesterol was the most effective inhibitor, followed by beta-sitosterol and stigmasterol; and at the same concentration, the sterols were more effective than CaCl(2), the classic membrane stabilizer.Ergosterol increased the methanol-initiated betacyanin leakage. Since none of the tested sterols reversed the betacyanin efflux induced by hydrogen peroxide, the sterols do not apparently act as antioxidants. The results are explained in terms of sterol-phospholipid interaction, based on stereochemistry and charge distribution.
95 citations
TL;DR: Catalase can be assayed very simply with the oxygen cathode, by measuring the initial rate of oxygen release from a solution of hydrogen peroxide or sodium perborate, because the substrate concentration is high enough, and the time short enough, to prevent decreasing rates during the reaction.
86 citations
77 citations
TL;DR: It was concluded that the major hemolysin of the Mycoplasma species examined is a peroxide, and Guinea pig erythrocytes were found to be the most susceptible to lysis by myCoplasma, and rabbit ery Throatcytes was found to been the least susceptible.
Abstract: Various methods for the detection of hemolysin production by Mycoplasma species were compared. Inoculation of blood-agar by the push-block method and by use of concentrated mycoplasma cell suspensions was compared with the agar-overlay technique. The preferred method was direct surface inoculation of concentrated suspensions onto the blood-agar. Among the conditions tested, refrigeration of 48-hr cultures gave the best results. A wide variety of mycoplasma species were tested for hemolytic activity towards rabbit, sheep, guinea pig, duck, and chicken bloods. Guinea pig erythrocytes were found to be the most susceptible to lysis by mycoplasma, and rabbit erythrocytes were found to be the least susceptible. A sensitive technique for the detection of peroxide production by mycoplasma strains, employing agar containing benzidine and sheep blood, was used. With this method, peroxide production could be correlated with hemolysis on blood-agar. Peroxidase and catalase inhibited both the benzidine reaction and hemolysis. It was concluded that the major hemolysin of the Mycoplasma species examined is a peroxide. Images
76 citations
TL;DR: Thiol oxidation by a lipid peroxide or hydrogen peroxide was as efficient in denatured non-haem proteins as in small thiols and the thiol group was found to be probably the group in proteins most sensitive to modification by peroxides.
Abstract: 1. Thiol oxidation by a lipid peroxide or hydrogen peroxide was as efficient in denatured non-haem proteins as in small thiols. Both peroxides were relatively ineffective in oxidizing haemoprotein thiols, especially at low pH. Increased amounts of haematin decreased greatly the efficiency of GSH oxidation by peroxides especially at low pH. 2. Other than the haematin ring, the thiol group was found to be probably the group in proteins most sensitive to modification by peroxides. 3. At low concentrations, the fatty acid moiety of a lipid peroxide appeared to impede thiol oxidation in proteins, probably by hydrophobic bonding to the protein, rather than to stimulate thiol oxidation by denaturing the protein and thereby increasing the exposure and reactivity of the thiol group. 4. The relative rates of thiol oxidation by peroxides in the different thiols were: haemoprotein thiols>small thiols>other protein thiols. In all cases, thiol oxidation was much more rapid by the lipid peroxide than by hydrogen peroxide.
TL;DR: It has been confirmed that certain buffer components have marked inhibitory effects on the catalatic reaction and that, in unbuffered systems,Catalatic activity is substantially independent of pH in the range 4.7-10.5.
Abstract: 1. A re-examination of the catalase-hydrogen peroxide reaction at high substrate concentrations, by using the quenched-flow technique, reveals a more complex kinetic behaviour than that previously reported. At constant reaction time the catalatic process obeys Michaelis-Menten kinetics, but the apparent Michaelis constant is markedly time-dependent, whereas the conventional catalase activity is independent of time. 2. The kinetics of the ;time effect' were analysed and it is suggested that the effect derives from the formation of an inactive species (thought to be catalase Compound II). The process shows Michaelis-Menten kinetics, with a Michaelis constant equal to that for the catalatic reaction in the limit of zero reaction time. 3. It has been confirmed that certain buffer components have marked inhibitory effects on the catalatic reaction and that, in unbuffered systems, catalatic activity is substantially independent of pH in the range 4.7-10.5.
TL;DR: In this paper, the Raman and infrared spectra have been measured of a range of transition-metal complexes involving bidentate or bridging peroxide groups, and also of those containing the hydroperoxide ligand or hydrogen peroxide of crystallisation.
Abstract: The Raman and infrared spectra have been measured of a range of transition-metal complexes involving bidentate or bridging peroxide groups, and also of those containing the hydroperoxide ligand or hydrogen peroxide of crystallisation. Assignments of fundamental modes are suggested; the results can be used to distinguish between the various types of peroxide complex.
Journal Article•
TL;DR: Both an electron source and oxygen are required for streptonigrin to exert its greatest lethal effect, which suggests that a reaction product of oxygen and intracellularly reduced stretonigrin is the lethal agent.
Abstract: Streptonigrin is lethal to cultures of Escherichia coli at concentrations that allow synthesis of DNA, RNA, and protein to continue. At higher concentrations DNA synthesis is preferentially inhibited. The lethal event is accompanied by DNA degradation, an effect enhanced if protein synthesis is also inhibited by witholding a required amino acid or by adding chloramphenicol. The degradation products, which are released into the culture medium, include nucleotides and bases, but no unusual products were detected. Both an electron source and oxygen are required for streptonigrin to exert its greatest lethal effect. This suggests that a reaction product of oxygen and intracellularly reduced streptonigrin is the lethal agent. This agent is likely to be a peroxide or peroxy free radical but is not hydrogen peroxide.
TL;DR: The reaction between olefins, N-chloroacetamide or 1,3-dibromo-5,5-dimethylhydantoin, and hydrogen peroxide affords β-halohydroperoxides in good yields as discussed by the authors.
Abstract: The reaction between olefins, N-chloroacetamide or 1,3-dibromo-5,5-dimethylhydantoin, and hydrogen peroxide affords β-halohydroperoxides in good yields These compounds react extremely rapidly in basic solution to give products which depend upon their structure The 3-halo-2,3-dimethyl-2-butyl hydroperoxides form 2,3-dimethyl-3-hydroperoxy-1-butene and from the 2-halo-1,2-dimethylcyclohexyl hydroperoxides 1-methyl-2-methylene-cyclohexyl hydroperoxide is obtained No allylic hydroperoxide can be detected from the reaction between base and 3-bromo-2-methyl-2-butyl hydroperoxide Mainly cleavage products, acetone and acetaldehyde, are formed together with some 2,3-epoxy-2-methylbutane The reaction between base and 2-bromo-1-phenylethyl hydroperoxide gives styrene oxide, benzoic acid, and some benzaldehyde From trans-2-bromocyclohexyl hydroperoxide, trans-2-bromocyclohexanol, cyclohexene oxide, and some trans-1,2-cyclohexanediol are obtained upon reaction with base No evidence for the formation of the ally
TL;DR: It is shown that glycine is a substrate of l -amino acid oxidase, which is capable of measuring 0.005 μg of enzyme or the oxidation of 0.5 nmole of amino acid.
TL;DR: An investigation was made of the death-rate of Bacillus subtilis spores in suspension in hydrogen peroxide concentrations of 10, 15 and 20% at 25, 50, 60, 70 and 80°C, with results found to be warranted in the temperature range 60–80°C.
Abstract: An investigation was made of the death-rate of Bacillus subtilis spores in suspension in hydrogen peroxide concentrations of 10, 15 and 20% at 25, 50, 60, 70 and 80°C. Average logarithmic survival curves were plotted against normal time and death-rate constants and Q10 values were calculated from the graphically determined decimal reduction times. This treatment of the experimental findings was found to be warranted in the temperature range 60–80°C. The first-order death-rate constant was ∽ 0·1 s−1 for 10% hydrogen peroxide solution at 60°C and the Q10 was about 1·6. Increases in the concentration from 10 to 15% and from 15 to 20% each gave an increase of about 50% in the rate constant. The application of these data to commercial practice is discussed.
TL;DR: In this article, the standard potential (reduction) of the system O2 + 2H+ + 2e = H2O2 is investigated. And it appears that the oxide system having potential E 0 lower than E′ 0 is a poor catalyst.
TL;DR: In this paper, the kinetics of the cupric salt-catalysed autoxidation of L -ascorbic aid have been studied in unbuffered aqueous solutions at ca. 35°.
TL;DR: Dihydroxyphenols were shown to have a marked inhibitory effect on these reactions and to account for the initial phase of low activity that is always observed in aqueous extracts prepared from the floret tissue.
Abstract: 1. Two enzymes were shown to be necessary for the production of ethylene from methional; they were separated from extracts of cauliflower florets by fractionation on Sephadex and other methods. 2. The first enzyme, generating hydrogen peroxide, appears to be similar to the fungal glucose oxidase, for like the latter it is highly specific for its substrate d-glucose. 3. The second enzyme, in the presence of cofactors and peroxide generated by the first enzyme, cleaves methional to ethylene. 4. It was also found that hydrogen peroxide in these reactions may be replaced by hydroperoxide generated from linolenic acid by lipoxidase enzymes. 5. Dihydroxyphenols were shown to have a marked inhibitory effect on these reactions and to account for the initial phase of low activity that is always observed in aqueous extracts prepared from the floret tissue.
Journal Article•
TL;DR: Catalase activities of intact cells and cell-free extracts of cultures 25042, 558, and 196E were similar, but resistance to H(2)O( 2) at 37.8 C was greater for culture 196E, and the lower resistance of culture 25042 was related to low catalase activity of whole cells of this culture, which were only one-third that of whole Cells of culture 196 E.
Abstract: Catalase activities of intact cells and cell-free extracts of coagulase-positive staphylococcal cultures 105B and 558D isolated from milk, culture 25042 from a clinical source, and Staphylococcus aureus 196E were determined at 32.2 C. Cultures were treated with 0.025 and 0.05% hydrogen peroxide at 37.8 and 54.4 C and without hydrogen peroxide at 54.4 C to determine the relationship between catalase activity and resistance to these treatments. The relationship held true for cultures 105B and 196E; culture 105B had the lowest catalase activity and lowest resistance to H2O2 at 37.8 C, whereas S. aureus 196E possessed a high catalase activity and was most resistant at 37.8 C. Catalase activities of cell-free extracts of cultures 25042, 558, and 196E were similar, but resistance to H2O2 at 37.8 C was greater for culture 196E. The lower resistance of culture 25042 was related to low catalase activities of whole cells of this culture, which were only one-third that of whole cells of culture 196E. Culture 558 was least resistant to heat treatment at 54.4 C and showed the greatest sensitivity to added H2O2 at this temperature.
TL;DR: The photolysis of hydrogen peroxide in the presence of phenols in aqueous solution was used for the hydroxylation of various phenols on a preparative scale.
TL;DR: The mechanism of the autoxidation of iron(II) in perchlorate media is discussed in this article, where it is concluded that the formation of a species containing two OH ions for each iron atom, Fe(OH)2aq, formed rapidly after raising the pH is responsible for this increase in rate.
Abstract: The rate of the reaction of iron(II) with hydrogen peroxide increases in perchlorate media at high pH until a high limiting rate is attained. This has been interpreted analogously to the effect of other anions on the reaction, and it is concluded that the formation of a species containing two OH– ions for each iron atom, Fe(OH)2aq, formed rapidly after raising the pH, is responsible for this increase in rate. This is comparable with the effect of fluoride ions on this reaction. pH-Difference measurements in the absence of H2O2 show that FeOH+aq and Fe2+aq are the predominant species of iron at pH =ca. 3, and suggest that at pH > 4 a hydrated dimer (Fe2+H2OFe2+)aq is formed slowly via Fe(OH)2,aq. Thermodynamic data for the formation of FeOH+aq and the Arrhenius parameters for the reaction of Fe(OH)2,aq with H2O2 are given. The mechanism of the autoxidation of iron(II) in perchlorate media is discussed.
TL;DR: Results indicate the utility of enzymatic methods to the trace determination of metal ion inhibitors and suggest the decreased rate of the enzyme-catalyzed, aerobic oxidation of glucose to gluconic acid and hydrogen peroxide can be followed spectrophotometrically.
Abstract: The inhibition of the glucose oxidase enzyme by three heavy metal inhibitors, Ag(I), Hg(II), and Pb(II) is reported. The method for the microdetermination of these metals is based on the decreased rate of the enzyme-catalyzed, aerobic oxidation of glucose to gluconic acid and hydrogen peroxide. In the presence of horseradish peroxidase, the rapid oxidation ofo-dianisidine by hydrogen peroxide can be followed spectrophotometrically at 440 nm. Silver(I) has been determined in the range of 0.005 to 0.2μg/ml with an absolute error of less than 14 ng. Mercury(II) has been determined in the range of 0.1 to 0.4μg/ml with a maximum error of 34 ng. Below a concentration of 260μg/ml Pb(II), no appreciable inhibition was observed. Results indicate the utility of enzymatic methods to the trace determination of metal ion inhibitors.