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 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 Catalase and glutathione peroxidase are equally active in detoxification of hydrogen peroxide in human erythrocytes

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 334-339 ◽  
Author(s):  
GF Gaetani ◽  
S Galiano ◽  
L Canepa ◽  
AM Ferraris ◽  
HN Kirkman
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Human Erythrocytes ◽  
Glutathione Pathway ◽  
Toxic Substrate ◽  
Glucose 6 Phosphate Dehydrogenase

Abstract Genetic deficiencies of glucose-6-phosphate dehydrogenase (G6PD) and NADPH predispose affected erythrocytes to destruction from peroxides. Conversely, genetic deficiencies of catalase do not predispose affected erythrocytes to peroxide-induced destruction. These observations have served to strengthen the assumption that the NADPH/glutathione/glutathione peroxidase pathway is the principal means for disposal of H2O2 in human erythrocytes. Recently, however, mammalian catalase was found to have tightly bound NADPH and to require NADPH for the prevention and reversal of inactivation by its toxic substrate (H2O2). Since both catalase and the glutathione pathway are dependent on NADPH for function, this finding raises the possibility that both mechanisms destroy H2O2 in human erythrocytes. A comparison of normal and acatalasemic erythrocytes in the present study indicated that catalase accounts for more than half of the destruction of H2O2 when H2O2 is generated at a rate comparable to that which leads to hemolysis in G6PD- deficient erythrocytes.

scholarly journals Predominant role of catalase in the disposal of hydrogen peroxide within human erythrocytes

Blood ◽  
1996 ◽  
Vol 87 (4) ◽  
pp. 1595-1599 ◽  
Author(s):  
GF Gaetani ◽  
AM Ferraris ◽  
M Rolfo ◽  
R Mangerini ◽  
S Arena ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Human Erythrocytes ◽  
Predominant Role ◽  
Intact Cells ◽  
Free System ◽  
Major Function ◽  
Relative Contribution ◽  
A Cell

Purified enzymes were mixed to form a cell-free system that simulated the conditions for removal of hydrogen peroxide within human erythrocytes. Human glutathione peroxidase disposed of hydrogen peroxide (H2O2) at a rate that was only 17% of the rate at which human catalase simultaneously removed hydrogen peroxide. The relative rates observed were in agreement with the relative rates predicted from the kinetic constants of the two enzymes. These results confirm two earlier studies on intact erythrocytes, which refuted the notion that glutathione peroxidase is the primary enzyme for removal of hydrogen peroxide within erythrocytes. The present findings differ from the results with intact cells, however, in showing that glutathione peroxidase accounts for even less than 50% of the removal of hydrogen peroxide. A means is proposed for calculating the relative contribution of glutathione peroxidase and catalase in other cells and species. The present results raise the possibility that the major function of glutathione peroxidase may be the disposal of organic peroxides rather than the removal of hydrogen peroxide.

scholarly journals Catalase and glutathione peroxidase are equally active in detoxification of hydrogen peroxide in human erythrocytes

Blood ◽  
1989 ◽  
Vol 73 (1) ◽  
pp. 334-339 ◽  
Author(s):  
GF Gaetani ◽  
S Galiano ◽  
L Canepa ◽  
AM Ferraris ◽  
HN Kirkman
Keyword(s):  
Hydrogen Peroxide ◽  
Glutathione Peroxidase ◽  
Human Erythrocytes ◽  
Glutathione Pathway ◽  
Toxic Substrate ◽  
Glucose 6 Phosphate Dehydrogenase

Genetic deficiencies of glucose-6-phosphate dehydrogenase (G6PD) and NADPH predispose affected erythrocytes to destruction from peroxides. Conversely, genetic deficiencies of catalase do not predispose affected erythrocytes to peroxide-induced destruction. These observations have served to strengthen the assumption that the NADPH/glutathione/glutathione peroxidase pathway is the principal means for disposal of H2O2 in human erythrocytes. Recently, however, mammalian catalase was found to have tightly bound NADPH and to require NADPH for the prevention and reversal of inactivation by its toxic substrate (H2O2). Since both catalase and the glutathione pathway are dependent on NADPH for function, this finding raises the possibility that both mechanisms destroy H2O2 in human erythrocytes. A comparison of normal and acatalasemic erythrocytes in the present study indicated that catalase accounts for more than half of the destruction of H2O2 when H2O2 is generated at a rate comparable to that which leads to hemolysis in G6PD- deficient erythrocytes.

scholarly journals Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3844
Author(s):  
Lijuan Li ◽  
Bingdong Li ◽  
Liwei Feng ◽  
Xiaoqiu Zhang ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Reaction Medium ◽  
Pure Tio2 ◽  
H2o2 Production ◽  
Tio2 Photocatalyst ◽  
H2o2 Decomposition ◽  
Spin Resonance ◽  
Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

scholarly journals The complex of phosphatidylinositol 4,5-bisphosphate and calcium ions is not responsible for Ca(2+)-induced loss of phospholipid asymmetry in the human erythrocyte: a study in Scott syndrome, a disorder of calcium- induced phospholipid scrambling

Blood ◽  
1995 ◽  
Vol 86 (5) ◽  
pp. 1983-1991 ◽  
Author(s):  
EM Bevers ◽  
T Wiedmer ◽  
P Comfurius ◽  
J Zhao ◽  
EF Smeets ◽  
...  
Keyword(s):  
Lipid Vesicles ◽  
Human Erythrocytes ◽  
Mechanism Analysis ◽  
Membrane Phospholipids ◽  
Mole Percent ◽  
Cellular Processes ◽  
Phospholipid Asymmetry ◽  
Dependent Cell ◽  
Normal Human ◽  
State Concentration

Elevation of cytoplasmic Ca2+ levels in human erythrocytes induces a progressive loss of membrane phospholipid asymmetry, a process that is impaired in erythrocytes from a patient with Scott syndrome. We show here that porcine erythrocytes are similarly incapable of Ca(2+)- induced redistribution of membrane phospholipids. Because a complex of phosphatidylinositol 4,5-bisphosphate (PIP2) and Ca2+ has been proposed as the mediator of enhanced transbilayer movement of lipids (J Biol Chem 269:6347,1994), these cell systems offer a unique opportunity for testing this mechanism. Analysis of both total PIP2 content and the metabolic-resistant pool of PIP2 that remains after incubation with Ca2+ ionophore showed no appreciable differences between normal and Scott erythrocytes. Moreover, porcine erythrocytes were found to have slightly higher levels of both total and metabolic-resistant PIP2 in comparison with normal human erythrocytes. Although loading of normal erythrocytes with exogenously added PIP2 gave rise to a Ca(2+)-induced increase in prothrombinase activity and apparent transbilayer movement of nitrobenzoxadiazolyl (NBD)-phospholipids, these PIP2-loaded cells were also found to undergo progressive Ca(2+)-dependent cell lysis, which seriously hampers interpretation of these data. Moreover, loading Scott cells with PIP2 did not abolish their impaired lipid scrambling, even in the presence of a Ca(2+)-ionophore. Finally, artificial lipid vesicles containing no PIP2 or 1 mole percent of PIP2 were indistinguishable with respect to transbilayer movement of NBD- phosphatidylcholine in the presence of Ca2+. Our findings suggest that Ca(2+)-induced redistribution of membrane phospholipids cannot simply be attributed to the steady-state concentration of PIP2, and imply that such lipid movement is regulated by other cellular processes.

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