Hydrogen peroxide-scavenging enzymes and antioxidants in Echinochloa frumentacea as affected by triazole growth regulators

1992 ◽  
Vol 11 (4) ◽  
pp. 441-443 ◽  
Author(s):  
N. Sankhla ◽  
A. Upadhyaya ◽  
Tim D. Davis ◽  
D. Sankhla
Keyword(s):  
Hydrogen Peroxide ◽  
Growth Regulators ◽  
Scavenging Enzymes ◽  
Echinochloa Frumentacea

scholarly journals Mesenchymal Stem Cells Restore Frataxin Expression and Increase Hydrogen Peroxide Scavenging Enzymes in Friedreich Ataxia Fibroblasts

PLoS ONE ◽  
2011 ◽  
Vol 6 (10) ◽  
pp. e26098 ◽  
Author(s):  
Kevin Kemp ◽  
Elizabeth Mallam ◽  
Kelly Hares ◽  
Jonathan Witherick ◽  
Neil Scolding ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Friedreich Ataxia ◽  
Scavenging Enzymes

Activities of Hydrogen Peroxide-Scavenging Enzymes in Germinating Wheat Seeds

1993 ◽  
Vol 44 (1) ◽  
pp. 127-132 ◽  
Author(s):  
ISMAIL CAKMAK ◽  
DRAGANA STRBAC ◽  
HORST MARSCHNER
Keyword(s):  
Hydrogen Peroxide ◽  
Scavenging Enzymes ◽  
Wheat Seeds

scholarly journals Hydrogen Peroxide Fluxes and Compartmentalization inside Growing Escherichia coli

2001 ◽  
Vol 183 (24) ◽  
pp. 7182-7189 ◽  
Author(s):  
Lauren Costa Seaver ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Permeability Coefficient ◽  
Growth Conditions ◽  
Scavenging Activity ◽  
Glucose Medium ◽  
Alkyl Hydroperoxide ◽  
Internal Concentration ◽  
Order Of Magnitude ◽  
Scavenging Enzymes

ABSTRACT Escherichia coli generates about 14 μM hydrogen peroxide (H2O2) per s when it grows exponentially in glucose medium. The steady-state intracellular concentration of H2O2 depends on the rates at which this H2O2 is dissipated by scavenging enzymes and by efflux from the cell. The rates of H2O2 degradation by the two major scavenging enzymes, alkyl hydroperoxide reductase and catalase, were quantified. In order to estimate the rate of efflux, the permeability coefficient of membranes for H2O2 was determined. The coefficient is 1.6 × 10−3 cm/s, indicating that permeability is substantial but not unlimited. These data allowed internal H2O2 fluxes and concentrations to be calculated. Under these growth conditions, Ahp scavenges the majority of the endogenous H2O2, with a small fraction degraded by catalase and virtually none persisting long enough to penetrate the membrane and exit the cell. The robust scavenging activity maintains the H2O2 concentration inside glucose-grown cells at <10−7 M, substantially below the level (10−6 M) at which toxicity is evident. When extracellular H2O2 is present, its flux into the cell can be rapid, but the internal concentration may still be an order of magnitude lower than that outside. The presence of such gradients was confirmed in experiments that revealed different degrees of oxidative stress in cocultured scavenger-deficient mutants. The limited permeability of membranes to H2O2rationalizes the compartmentalization of scavenging systems and predicts that bacteria that excrete redox-cycling drugs do not experience the same H2O2 dose that they impose on their competitors.

Inhibition of abscisic acid-induced stomatal closure by ethylene is related to the change of hydrogen peroxide levels in guard cells in broad bean

2011 ◽  
Vol 59 (8) ◽  
pp. 781 ◽  
Author(s):  
XiGui Song ◽  
XiaoPing She ◽  
Juan Wang
Keyword(s):  
Hydrogen Peroxide ◽  
Ascorbic Acid ◽  
Abscisic Acid ◽  
Nadph Oxidase ◽  
Broad Bean ◽  
Stomatal Closure ◽  
Guard Cells ◽  
Diphenylene Iodonium ◽  
Scavenging Enzymes ◽  
Exogenous H2o2

We analysed the role and relationship between hydrogen peroxide (H2O2) reduction and the inhibition of abscisic acid (ABA)-induced stomatal closure by ethylene. Like ascorbic acid (ASA), the most important reducing substrate for H2O2 removal, catalase, one of the H2O2 scavenging enzymes and diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, both ethylene-releasing compound 2-chloroethylene phosphonic acid (ethephon, ETH) and 1-aminocyclopropane-1-carboxylic acid (ACC), the immediate precursor of ethylene, were found to inhibit stomatal closure by ABA and to reduce H2O2 levels by ABA in guard cells, indicating that ethylene-caused inhibition of ABA-induced stomatal closure involves reduction of H2O2 levels in guard cells. Additionally, similar to ASA and catalase, ACC/ETH not only suppressed H2O2-induced stomatal closure and H2O2 levels in guard cells treated with exogenous H2O2 in light, but also reopened the stomata which had been closed by ABA and reduced H2O2 levels that had been generated by ABA. The abovementioned effects of ACC and ETH were dissimilar to that of diphenylene iodonium, an inhibitor of the H2O2-generating enzyme NADPH oxidase, which not only had incapability to reduce H2O2 levels by exogenous H2O2 but also could not abolish H2O2 that had been generated by ABA. So we suggest that ethylene probably induces H2O2 removal and reduces H2O2 levels in Vicia faba guard cells, and finally inhibits stomatal closure induced by ABA.

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