Direct Evidence for a Tyrosine Radical in the Reaction of CytochromecOxidase with Hydrogen Peroxide†

Biochemistry ◽  
1999 ◽  
Vol 38 (29) ◽  
pp. 9179-9184 ◽  
Author(s):  
Fraser MacMillan ◽  
Aimo Kannt ◽  
Julia Behr ◽  
Thomas Prisner ◽  
Hartmut Michel
Keyword(s):  
Hydrogen Peroxide ◽  
Direct Evidence ◽  
Tyrosine Radical

Cyclic dipeptide peroxosolvates: first direct evidence for hydrogen bonding between hydrogen peroxide and a peptide backbone

CrystEngComm ◽  
2019 ◽  
Vol 21 (33) ◽  
pp. 4961-4968 ◽  
Author(s):  
Andrei V. Churakov ◽  
Dmitry A. Grishanov ◽  
Alexander G. Medvedev ◽  
Alexey A. Mikhaylov ◽  
Tatiana A. Tripol'skaya ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Direct Evidence ◽  
Valuable Insight ◽  
Cyclic Dipeptide ◽  
Peptide Backbone ◽  
Redox Interaction ◽  
Insight Into

The crystal structures of cyclic dipeptide peroxosolvates provide valuable insight into the non-redox interaction of hydrogen peroxide with the peptide backbone.

scholarly journals Direct Evidence for Catalase as the Predominant H2O2 -Removing Enzyme in Human Erythrocytes

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4973-4978 ◽  
Author(s):  
Sebastian Mueller ◽  
Hans-Dieter Riedel ◽  
Wolfgang Stremmel
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Enzyme Inhibition ◽  
Direct Evidence ◽  
Human Erythrocytes ◽  
H2o2 Concentration ◽  
H2o2 Decomposition ◽  
Erythrocyte Catalase ◽  
Normal Human ◽  
Kinetics Of

Abstract Decomposition of hydrogen peroxide (H2O2 ) at physiological levels was studied in human erythrocytes by means of a recently developed sensitive H2O2 assay. The exponential decay of H2O2 in the presence of purified erythrocyte catalase was followed down to 10−9 mol/L H2O2 at pH 7.4. H2O2 decomposition by purified erythrocyte glutathione peroxidase (GPO) could be directly observed down to 10−7 mol/L H2O2 . No enzyme inhibition was observed at these low H2O2 concentrations. Catalase and GPO activities can be determined separately in a titrated mixture of purified enzymes, which simulates the conditions of H2O2 removal by the erythrocyte. Experiments with fresh human hemolysate allowed us to determine H2O2 decomposition by catalase and GPO using these enzymes in their original quantitative ratio. The different kinetics of these enzymes are shown: H2O2 decomposition by catalase depends linearly on H2O2 concentration, whereas that by GPO becomes saturated at concentrations above 10−6 mol/L H2O2 . Even at very low H2O2 concentrations GPO reaches only approximately 8% of the rate at which catalase simultaneously degrades H2O2 . These data indicate an almost exclusive role for catalase in the removal of H2O2 in normal human erythrocytes.

scholarly journals Human granulocyte generation of hydroxyl radical.

1978 ◽  
Vol 147 (2) ◽  
pp. 316-323 ◽  
Author(s):  
S J Weiss ◽  
P K Rustagi ◽  
A F LoBuglio
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Direct Evidence ◽  
Membrane Perturbation ◽  
Human Granulocytes

Human granulocytes were capable of oxidizing 2-keto-4 thiomethylbutyric acid to ethylene during phagocytosis or membrane perturbation. The reaction required hydrogen peroxide and superoxide and in addition was inhibited by various hydroxyl radical (OH) scavengers. These observations represent direct evidence for the generation of OH by human granulocytes. Further, inhibition of ethylene generation by azide and cyanide suggests that OH generation in granulocytes may be linked to myeloperoxidase.

Abstract 3629: Crucial Role of Nitric Oxide Synthases System in Endothelium-Dependent Hyperpolarization in Mice

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Aya Takaki ◽  
Keiko Morikawa ◽  
Yoshinori Murayama ◽  
Ender Tekes ◽  
Hiroto Yamagishi ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Hydrogen Peroxide ◽  
Antihypertensive Treatment ◽  
Direct Evidence ◽  
No Synthase ◽  
Mesenteric Arteries ◽  
Superoxide Anions ◽  
Nos Isoforms ◽  
Nos Gene

We have previously demonstrated that endothelium-derived hydrogen peroxide (H 2 O 2 ) is an endothelium-derived hyperpolarizing factor (EDHF) in mouse and human mesenteric arteries and porcine coronary microvessels. We also have demonstrated that endothelial NO synthase (eNOS) is a major source of EDHF/H 2 O 2 , where Cu,Zn-superoxide dismutase (SOD) plays an important role to dismutate eNOS-derived superoxide anions to EDHF/H 2 O 2 in animals and humans. However, the mechanism for the endothelial production of H 2 O 2 as an endogenous EDHF remains to be elucidated. Indeed, some EDHF-mediated responses still remain in singly eNOS −/− mice and the remaining responses are also sensitive to catalase that dismutates H 2 O 2 to form water and oxygen. It is widely known that 3 NOS isoforms (neuronal, inducible, and endothelial) compensate each other. In this study, we examined the effects of genetic disruption of all NOS isoforms (n/i/eNOS −/− ) on EDHF responses in mice. We examined the contribution of the whole NOS system to EDHF-mediated responses in eNOS −/− , n/eNOS −/− and n/i/eNOS −/− mice that we have recently generated. Isometric tensions and membrane potentials were recorded by organ chamber experiments and microelectrode technique, respectively. EDHF-mediated relaxations and hyperporalizations in response to acetylcholine of mesenteric arteries were progressively reduced as the number of disrupted NOS genes increased (n=6 each), whereas vascular smooth muscle functions were preserved (n=6 each). Expressions of endothelial NOS isoforms in the NOSs −/− mice were compensated by NOS gene that had not been disrupted (n=5 each). Laser confocal microscopic examination demonstrated that endothelial H 2 O 2 and superoxide production was absent in n/i/eNOS −/− mice (n=3–5), whereas antihypertensive treatment with hydralazine failed to improve the EDHF-mediated responses (n= 4). Involvement of NOS uncoupling was ruled out as modulation of BH 4 synthesis had no effects (n=6–7) and BH 4 /BH 2 ratio (an index of BH 4 bioavailability) was preserved (n=4). These results provide the first direct evidence that EDHF-mediated responses are totally dependent on endothelial NOSs system in mouse mesenteric arteries.

scholarly journals Direct Evidence for Catalase as the Predominant H2O2 -Removing Enzyme in Human Erythrocytes

Blood ◽  
1997 ◽  
Vol 90 (12) ◽  
pp. 4973-4978 ◽  
Author(s):  
Sebastian Mueller ◽  
Hans-Dieter Riedel ◽  
Wolfgang Stremmel
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Enzyme Inhibition ◽  
Direct Evidence ◽  
Human Erythrocytes ◽  
H2o2 Concentration ◽  
H2o2 Decomposition ◽  
Erythrocyte Catalase ◽  
Normal Human ◽  
Kinetics Of

Decomposition of hydrogen peroxide (H2O2 ) at physiological levels was studied in human erythrocytes by means of a recently developed sensitive H2O2 assay. The exponential decay of H2O2 in the presence of purified erythrocyte catalase was followed down to 10−9 mol/L H2O2 at pH 7.4. H2O2 decomposition by purified erythrocyte glutathione peroxidase (GPO) could be directly observed down to 10−7 mol/L H2O2 . No enzyme inhibition was observed at these low H2O2 concentrations. Catalase and GPO activities can be determined separately in a titrated mixture of purified enzymes, which simulates the conditions of H2O2 removal by the erythrocyte. Experiments with fresh human hemolysate allowed us to determine H2O2 decomposition by catalase and GPO using these enzymes in their original quantitative ratio. The different kinetics of these enzymes are shown: H2O2 decomposition by catalase depends linearly on H2O2 concentration, whereas that by GPO becomes saturated at concentrations above 10−6 mol/L H2O2 . Even at very low H2O2 concentrations GPO reaches only approximately 8% of the rate at which catalase simultaneously degrades H2O2 . These data indicate an almost exclusive role for catalase in the removal of H2O2 in normal human erythrocytes.

scholarly journals Catalytic and induced reactions. Part II.—Catalytic and induced oxidation in the presence of salts of iron

1924 ◽  
Vol 105 (730) ◽  
pp. 148-164 ◽  
Keyword(s):  
Hydrogen Peroxide ◽  
Organic Compounds ◽  
Potassium Iodide ◽  
Ferrous Iron ◽  
Direct Evidence ◽  
Ferrous Sulphate ◽  
Intermediate Compound ◽  
Neutral Solution ◽  
Physiological Importance ◽  
Quantitative Manner

The reactions comprised under this heading include many example of physiological importance and others well known to chemists— e. g. , the separation of iodine from potassium iodide in the presence of ferrous salts and hydrogen peroxide, first discovered by Schönbein, the process being known consequently as “Schönbein’s reaction”; and the oxidation of certain organic compounds in the presence of Fenton’s reagent (ferrous sulphate and hydrogen peroxide). Explanations of the observed phenomena have usually been based upon the hypothesis of an intermediate compound of iron; they have remained some-what tentative, however, since direct evidence of the formation of such compounds has not been forthcoming. Manchot, who investigated Schönbein’s reaction in a quantitative manner (1), came to the conclusion that hydrogen peroxide acted upon ferrous sulphate in neutral solution forming the perxide Fe 2 O 5 , since one equivalent of ferrous iron liberates two equivalents of iodine from potassium iodide, the latter being present in excess; allowing for the equivalent of oxygen necessary to transform ferrous iron into ferric, we obtain the total of three equivalents, or a formula of Fe 2 O 5 for the intermediate compound. He reached a similar conclusion from the study of the action of chromic and permanganic acids upon ferrous sulphate in the presence of acceptors; he was nevertheless quite unsuccessful in any attempt to isolate the postulated peroxides, nor have subsequent investigators fared better. Manchot decided, however, that their formation must be supposed in order to explain his results; and some such hypothesis would appear to be necessary in order to account for the reactions investigated by Fenton and others (2).

Tightly bound NADPH in Proteus mirabilis PR catalase

1989 ◽  
Vol 67 (6) ◽  
pp. 271-277 ◽  
Author(s):  
Hélène M. Jouve ◽  
Frédéric Beaumont ◽  
Isabelle Léger ◽  
Jacques Foray ◽  
Jean Pelmont
Keyword(s):  
Hydrogen Peroxide ◽  
Proteus Mirabilis ◽  
High Performance ◽  
Direct Evidence ◽  
Bovine Liver ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Enzyme Molecule ◽  
Complex Ii ◽  
Bovine Liver Catalase

Previous work with catalase from Proteus mirabilis PR, a mutant with high resistance to H2O2, had shown that two different forms of this enzyme, named A and B, could be resolved by anion exchange chromatography. The present results showed that catalase B differed from A by the presence of bound NADPH. Direct evidence for the presence of this dinucleotide within the bacterial catalase was obtained using high performance liquid chromatography. The obtention of pure catalase B without any addition of external NADPH showed that this dinucleotide was bound tightly to the protein as to be carried along with the protein during purification. Catalase complex II was formed from either-enzyme A or B by the continuous supply of low amounts of hydrogen peroxide as in the case of bovine liver catalase. The reversal of complex II formation from catalase B was obtained using a NADPH-regenerating system (isocitrate plus isocitrate dehydrogenase) in the absence of any added dinucleotide, confirming that this cofactor was present in the enzyme molecule. The addition of dinucleotide was required when performing the same experiment with catalase A. This was the first observation of NADPH binding by a bacterial catalase, and the results agreed with the former theory where NADPH is considered as a rescuer of the enzyme from inactivation in the form of complex II.Key words: catalase, bovine liver catalase, NADPH, Proteus mirabilis.

scholarly journals Site-specific spin trapping of tyrosine radicals in the oxidation of metmyoglobin by hydrogen peroxide

1998 ◽  
Vol 330 (3) ◽  
pp. 1293-1299 ◽  
Author(s):  
R. Michael GUNTHER ◽  
Richard A. TSCHIRRET-GUTH ◽  
H. Ewa WITKOWSKA ◽  
C. Yang FANN ◽  
P. David BARR ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Spin Trap ◽  
Sperm Whale ◽  
Spin Trapping ◽  
Tryptophan Residue ◽  
Radical Adduct ◽  
Unpaired Electron Density ◽  
Trapping Agent ◽  
Tyrosine Radical ◽  
Radical Yield

The reaction between metmyoglobin and hydrogen peroxide produces both a ferryl-oxo heme and a globin-centred radical(s) from the two oxidizing equivalents of the hydrogen peroxide. Evidence has been presented for localization of the globin-centred radical on one tryptophan residue and tyrosines 103 and 151. When the spin-trapping agent 5,5-dimethyl-1-pyrroline N-oxide (DMPO) is included in the reaction mixture, a radical adduct has been detected, but the residue at which that adduct is formed has not been determined. Replacement of either tryptophans 7 and 14 or tyrosines 146 and 151 with phenylalanine has no effect on the formation of DMPO adduct in the reaction with hydrogen peroxide. When tyrosine 103 is replaced with phenylalanine, however, only DMPOX, a product of the oxidation of the spin-trap, is detected. Tyrosine-103 is, therefore, the site of radical adduct formation with DMPO. The spin trap 2-methyl-2-nitrosopropane (MNP), however, forms radical adducts with any recombinant sperm whale metmyoglobin that contains either tyrosine 103 or 151. Detailed spectral analysis of the DMPO and MNP radical adducts of isotopically substituted tyrosine radical yield complete structural determinations. The multiple sites of trapping support a model in which the unpaired electron density is spread over a number of residues in the population of metmyoglobin molecules, at least some of which are in equilibrium with each other.

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