scholarly journals The mechanism of potentiation of horseradish peroxidase-catalysed oxidation of NADPH by porphyrins

1987 ◽  
Vol 242 (2) ◽  
pp. 611-613 ◽  
Author(s):  
J Van Steveninck ◽  
J P J Boegheim ◽  
T M A R Dubbelman ◽  
J Van der Zee
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Horseradish Peroxidase ◽  
Superoxide Radical ◽  
Experimental Results ◽  
Haematoporphyrin Derivative ◽  
Anaerobic Conditions ◽  
Catalysed Oxidation ◽  
Cytochrome C Reduction ◽  
Nadph Oxidation

Several porphyrins, including HpD (haematoporphyrin derivative), potentiate the oxidation of NADPH by horseradish peroxidase/H2O2. To elucidate the mechanism of potentiation, the following observations are relevant. During peroxidase-catalysed NADPH oxidation, O2-.(superoxide radical) is generated, as judged from superoxide dismutase-inhibitable cytochrome c reduction. This generation of O2-. is suppressed by HpD. Peroxidase-catalysed NADPH oxidation is stimulated by superoxide dismutase and by anaerobic conditions. Under anaerobic conditions HpD has no influence on peroxide-catalysed NADPH oxidation. Previous studies have shown that horseradish peroxidase is inhibited by O2-.. Thus the experimental results indicate that the potentiating effect of HpD can be explained by its ability to inhibit O2-. generation in the horseradish peroxidase/H2O2/NADPH system.

scholarly journals Neutrophils adherent to a nonphagocytosable surface (glomerular basement membrane) produce oxidants only at the site of attachment

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 161-166 ◽  
Author(s):  
MC Vissers ◽  
WA Day ◽  
CC Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Plasma Membrane ◽  
Cytochrome C ◽  
Basement Membrane ◽  
Horseradish Peroxidase ◽  
Cell Surface ◽  
Oxygen Uptake ◽  
Glomerular Basement Membrane ◽  
Cerium Chloride ◽  
Cytochrome C Reduction

Abstract Adherence of neutrophils to glomerular basement membrane containing immunoglobulin G aggregates was accompanied by a marked increase in oxygen uptake (eightfold). Very little of the O2 consumed was recovered as superoxide, measured by cytochrome c reduction, or as H2O2, measured with horseradish peroxidase and scopoletin. When neutrophils were incubated with the basement membrane preparation in the presence of cerium chloride to detect H2O2, electron micrographs showed cerium perhydroxide deposits in the contact area between the cells and the basement membrane, but not on the remainder of the cell surface. The results imply that superoxide is produced only where the plasma membrane is in contact with the basement membrane matrix, and that it mostly breaks down to H2O2 or undergoes other reactions at this site. The longer lifetime of H2O2 compared with that of superoxide allows some of the H2O2 produced to be detected in the medium. The results also suggest that the area of contact between the neutrophil and surfaces such as basement membrane is inaccessible to proteins in the medium, eg, cytochrome c. Circulating scavengers such as superoxide dismutase or catalase, or proteolytic inhibitors, may therefore be unable to control events occurring at this site.

scholarly journals Neutrophils adherent to a nonphagocytosable surface (glomerular basement membrane) produce oxidants only at the site of attachment

Blood ◽  
1985 ◽  
Vol 66 (1) ◽  
pp. 161-166
Author(s):  
MC Vissers ◽  
WA Day ◽  
CC Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Plasma Membrane ◽  
Cytochrome C ◽  
Basement Membrane ◽  
Horseradish Peroxidase ◽  
Cell Surface ◽  
Oxygen Uptake ◽  
Glomerular Basement Membrane ◽  
Cerium Chloride ◽  
Cytochrome C Reduction

Adherence of neutrophils to glomerular basement membrane containing immunoglobulin G aggregates was accompanied by a marked increase in oxygen uptake (eightfold). Very little of the O2 consumed was recovered as superoxide, measured by cytochrome c reduction, or as H2O2, measured with horseradish peroxidase and scopoletin. When neutrophils were incubated with the basement membrane preparation in the presence of cerium chloride to detect H2O2, electron micrographs showed cerium perhydroxide deposits in the contact area between the cells and the basement membrane, but not on the remainder of the cell surface. The results imply that superoxide is produced only where the plasma membrane is in contact with the basement membrane matrix, and that it mostly breaks down to H2O2 or undergoes other reactions at this site. The longer lifetime of H2O2 compared with that of superoxide allows some of the H2O2 produced to be detected in the medium. The results also suggest that the area of contact between the neutrophil and surfaces such as basement membrane is inaccessible to proteins in the medium, eg, cytochrome c. Circulating scavengers such as superoxide dismutase or catalase, or proteolytic inhibitors, may therefore be unable to control events occurring at this site.

scholarly journals The rate of reaction of superoxide radical ion with oxyhaemoglobin and methaemoglobin

1976 ◽  
Vol 155 (3) ◽  
pp. 503-510 ◽  
Author(s):  
H C Sutton ◽  
P B Roberts ◽  
C C Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Xanthine Oxidase ◽  
Rate Constants ◽  
Superoxide Radical ◽  
Radical Ions ◽  
Catalysed Oxidation ◽  
Rate Of Reaction ◽  
Radiolytic Reduction

Superoxide radical ions (O2-) produced by the radiolytic reduction of oxygenated formate solutions and by the xanthine oxidase-catalysed oxidation of xanthine were shown to oxidize the haem groups in oxyhaemoglobin and reduce those in methaemoglobin as in reactions (1) and (2): (see articles) Reaction (1) is suppressed by reaction (8) when [O2-]exceeds 10 muM, but consumes all the O2- generated in oxyhaemoglobin solutions when [oxyhaemoglobin] greater than 160 muM and [O2-]less than 1 nM at pH 7. The yield of reaction (2) is also maximal in methaemoglobin solutions under similar conditions, but less than one haem group is reduced per O2- radical. From studies of (a) the yield of reactions (1) and (2) at variable [haemoglobin] and rates of production of O2-, (b) their suppression by superoxide dismutase, and (c) equilibria observed with mixtures of oxyhaemoglobin and methaemoglobin, it is shown that k1/k2=0.7 +/- 0.2 and k1 = (4 +/- 1) × 10(3) M-1-S-1 At pH7, and k1 and k2 decrease with increasing pH. Concentrations and rate constants are expressed in terms of haem-group concentrations. Concentrations of superoxide dismutase observed in normal erythrocytes are sufficient to suppress reactions (1) and (2), and hence prevent the formation of excessive methaemoglobin.

scholarly journals The influence of porphyrins on iron-catalysed generation of hydroxyl radicals

1988 ◽  
Vol 250 (1) ◽  
pp. 197-201 ◽  
Author(s):  
J Van Steveninck ◽  
J P J Boegheim ◽  
T M A R Dubbelman ◽  
J Van der Zee
Keyword(s):  
Cytochrome C ◽  
Horseradish Peroxidase ◽  
Experimental Evidence ◽  
Xanthine Oxidase ◽  
Hydroxyl Radicals ◽  
Anion Radical ◽  
The Other ◽  
Haematoporphyrin Derivative ◽  
Other Hand

Uroporphyrin I, haematoporphyrin and haematoporphyrin derivative had no effect on O2-. generation during oxidation of hypoxanthine by xanthine oxidase and on the formation of hydroxyl radicals (OH.) in the hypoxanthine/xanthine oxidase/Fe3+-EDTA/deoxyribose system. On the other hand, these porphyrins strongly inhibited O2-. formation in a horseradish peroxidase/H2O2/NADPH mixture, whereas they augmented OH. generation in this system after addition of Fe3+-EDTA. Experimental evidence suggests that these observations should be ascribed to the formation of a porphyrin anion radical in the horseradish peroxidase/NADPH system. The formation of this anion radical was confirmed by e.s.r. spectroscopy. This radical is apparently unable to reduce cytochrome c, but it can replace O2-. in the OH.-generating Haber-Weiss reaction.

Mechanisms of Adriamycin-Dependent Oxygen Activation Catalyzed by NADPH-Cytochrome c-(Ferredoxin)-Oxidoreductase

1984 ◽  
Vol 39 (3-4) ◽  
pp. 261-267 ◽  
Author(s):  
Eva Paur ◽  
Richard J. Youngman ◽  
Edmund Lengfelder ◽  
Erich F. Elstner
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Reaction Vessel ◽  
Semiquinone Radical ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Ferredoxin Oxidoreductase ◽  
Nadph Cytochrome ◽  
Superoxide Formation ◽  
Electron Donation

Under aerobic conditions, O2 uptake and production of O2- and H2O2 by isolated NADPH - cytochrome c-(ferredoxin)-oxidoreductase from Euglena gracilis was strongly stimulated by adriamycin. Further stimulation was not observed with 0.1 mᴍ Fe3+-EDTA. Methionine fragmentation (measured as ethylene release), as a reliable indicator for the formation of OH- radical-like oxidants under aerobic conditions (100 μmol O2 in a 10 ml reaction vessel) was strongly stimulated by 0.1 mᴍ Fe3+-EDTA or, in the absence of iron, by partial anaerobiosis (1 μmol O2 per vessel). The highest rate of methionine fragmentation was observed under anaerobic conditions in the presence of both reduced adriamycin and added H2O2. Aerobic methionine fragmentation in the presence of adriamycin and Fe3+-EDTA was inhibited by superoxide dismutase and catalase by more than 90%, while methionine fragmentation under semianaerobiosis in the absence of Fe3+-EDTA was inhibited by superoxide dismutase to only about 50%, while catalase again inhibited by more than 90%. These results indicate that the adriamycin-catalyzed production of a strong oxidant appears to be governed by different mechanisms depending on oxygen availability; namely the production of a Fenton-type oxidant driven by adriamycin-catalyzed superoxide formation and also, the formation of the “crypto-OH- radical” by direct electron donation from the adriamycin semiquinone radical to H2O2 under oxygen limiting conditions

scholarly journals Superoxide dismutase-inhibitible reduction of cytochrome c by the alloxan radical. Implications for alloxan cytotoxicity

1982 ◽  
Vol 207 (3) ◽  
pp. 609-612 ◽  
Author(s):  
C C Winterbourn
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Xanthine Oxidase ◽  
Reduced Glutathione ◽  
Direct Reaction ◽  
Cytochrome C Reduction

Cytochrome c was reduced when superoxide was generated from xanthine oxidase in the presence of alloxan, and by the reaction of alloxan and with reduced glutathione. In each case, most of the reduction was inhibited by superoxide dismutase, but considerably more enzyme was required than with superoxide alone. This indicates that the superoxide dismutase-inhibitible cytochrome c reduction was mainly due to a direct reaction with the alloxan radical, and implies that other reactions that are inhibited by superoxide dismutase could be due to either alloxan radicals or superoxide.

Reduction of exogenous cytochrome c by Neurospora crassa conidia: effects of superoxide dismutase and blue light

1982 ◽  
Vol 152 (1) ◽  
pp. 151-156
Author(s):  
U Takahama ◽  
M Shimizu-Takahama ◽  
T Egashira
Keyword(s):  
Superoxide Dismutase ◽  
Cytochrome C ◽  
Neurospora Crassa ◽  
Blue Light ◽  
Photochemical Reactions ◽  
Antimycin A ◽  
Light Effect ◽  
Cytochrome C Reduction ◽  
Reducing Equivalents

The reduction of externally added cytochrome c by Neurospora crassa conidia was observed. The reduction was stimulated by antimycin A and suppressed partially by superoxide dismutase. When conidia were treated with diethyldithiocarbamate, which inactivated endogenous superoxide dismutase, the cytochrome c reduction was stimulated. Blue light also stimulated the cytochrome c reduction. Azide, which inhibits photochemical reactions mediated by flavins, suppressed the blue light effect. Superoxide dismutase partially suppressed the cytochrome c reduction in the light. The results suggest that O2(-) participates in the cytochrome c reduction by conidia and the flavins or flavoproteins are candidates for the receptor pigment of blue light to stimulate the cytochrome c reduction. It was also suggested that the redox component(s), which could directly transfer its reducing equivalents to exogenous cytochrome c, was present at the surface of conidia.

scholarly journals Hydroxylation of p-coumaric acid by horseradish peroxidase. The role of superoxide and hydroxyl radicals

1976 ◽  
Vol 153 (3) ◽  
pp. 513-518 ◽  
Author(s):  
B Halliwell ◽  
S Ahluwalia
Keyword(s):  
Superoxide Dismutase ◽  
Horseradish Peroxidase ◽  
Caffeic Acid ◽  
Hydroxyl Radicals ◽  
Superoxide Radical ◽  
Coumaric Acid ◽  
Low Concentrations ◽  
Superoxide Dismutase 3 ◽  
Superoxide Dismutase 2

1. In the presence of dihydroxyfumarate, horseradish peroxidase catalyses the conversion of p-coumaric acid into caffeic acid at pH 6. This hydroxylation is completely inhibited by superoxide dismutase. 2. Dihydroxyfumarate cannot be replaced by ascorbate H2O2, NADH, cysteine or sulphite. Peroxidase can be replaced by high (10 mM) concentrations of FeSO4, but this reaction is almost unaffected by superoxide dismutase. 3. Hydroxylation by the peroxidase/dihydroxyfumarate system is completely inhibited by low concentrations of Mn2+ or Cu2+. It is proposed that this is due to the ability of these metal ions to react with the superoxide radical O2–. 4. Hydroxylation is partially inhibited by mannitol, Tris or ethanol and completely inhibited by formate. This seems to be due to the ability of these reagents to react with the hydroxyl radical -OH. 5. It is concluded that O2– is generated during the oxidation of dihydroxyfumarate by peroxidase and reacts with H2O2 to produce hydroxyl radicals, which then convert p-coumaric acid into caffeic acid.

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