scholarly journals Amphibacillus xylanus NADH Oxidase and Salmonella typhimurium Alkyl-hydroperoxide Reductase Flavoprotein Components Show Extremely High Scavenging Activity for Both Alkyl Hydroperoxide and Hydrogen Peroxide in the Presence of S. typhimurium Alkyl-hydroperoxide Reductase 22-kDa Protein Component

1995 ◽  
Vol 270 (43) ◽  
pp. 25645-25650 ◽  
Author(s):  
Youichi Niimura ◽  
Leslie B. Poole ◽  
Vincent Massey
Keyword(s):  
Hydrogen Peroxide ◽  
Salmonella Typhimurium ◽  
Nadh Oxidase ◽  
Protein Component ◽  
Scavenging Activity ◽  
Alkyl Hydroperoxide Reductase ◽  
Alkyl Hydroperoxide

scholarly journals Alkyl Hydroperoxide Reductase Is the Primary Scavenger of Endogenous Hydrogen Peroxide in Escherichia coli

2001 ◽  
Vol 183 (24) ◽  
pp. 7173-7181 ◽  
Author(s):  
Lauren Costa Seaver ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Candidate Genes ◽  
Residual Activity ◽  
Aerobic Metabolism ◽  
Scavenging Activity ◽  
Wild Type ◽  
Alkyl Hydroperoxide Reductase ◽  
E Coli ◽  
Alkyl Hydroperoxide

ABSTRACT Hydrogen peroxide is generated during aerobic metabolism and is capable of damaging critical biomolecules. However, mutants ofEscherichia coli that are devoid of catalase typically exhibit no adverse phenotypes during growth in aerobic media. We discovered that catalase mutants retain the ability to rapidly scavenge H2O2 whether it is formed internally or provided exogenously. Analysis of candidate genes revealed that the residual activity is due to alkyl hydroperoxide reductase (Ahp). Mutants that lack both Ahp and catalase could not scavenge H2O2. These mutants excreted substantial amounts of H2O2, and they grew poorly in air. Ahp is kinetically a more efficient scavenger of trace H2O2 than is catalase and therefore is likely to be the primary scavenger of endogenous H2O2. Accordingly, mutants that lack Ahp accumulated sufficient hydrogen peroxide to induce the OxyR regulon, whereas the OxyR regulon remained off in catalase mutants. Catalase still has an important role in wild-type cells, because the activity of Ahp is saturated at a low (10−5 M) concentration of H2O2. In contrast, catalase has a high K m , and it therefore becomes the predominant scavenger when H2O2 concentrations are high. This arrangement is reasonable because the cell cannot provide enough NADH for Ahp to rapidly degrade large amounts of H2O2. In sum,E. coli does indeed generate substantial H2O2, but damage is averted by the scavenging activity of Ahp.

scholarly journals NADH oxidase and alkyl hydroperoxide reductase subunit C (peroxiredoxin) fromAmphibacillus xylanus form an oligomeric assembly

FEBS Open Bio ◽  
2015 ◽  
Vol 5 (1) ◽  
pp. 124-131 ◽  
Author(s):  
Toshiaki Arai ◽  
Shinya Kimata ◽  
Daichi Mochizuki ◽  
Keita Hara ◽  
Tamotsu Zako ◽  
...  
Keyword(s):  
Nadh Oxidase ◽  
Alkyl Hydroperoxide Reductase ◽  
Subunit C ◽  
Alkyl Hydroperoxide ◽  
Oligomeric Assembly

Studies on NADH oxidase and alkyl hydroperoxide reductase produced by Porphyromonas gingivalis

2004 ◽  
Vol 19 (3) ◽  
pp. 137-143 ◽  
Author(s):  
P. I. Diaz ◽  
P. S. Zilm ◽  
V. Wasinger ◽  
G. L. Corthals ◽  
A. H. Rogers
Keyword(s):  
Porphyromonas Gingivalis ◽  
Nadh Oxidase ◽  
Alkyl Hydroperoxide Reductase ◽  
Alkyl Hydroperoxide

Streptococcus mutans H2O2-forming NADH oxidase is an alkyl hydroperoxide reductase protein

2000 ◽  
Vol 28 (1) ◽  
pp. 108-120 ◽  
Author(s):  
Leslie B Poole ◽  
Masako Higuchi ◽  
Mamoru Shimada ◽  
Marco Li Calzi ◽  
Yoshiyuki Kamio
Keyword(s):  
Streptococcus Mutans ◽  
Nadh Oxidase ◽  
Alkyl Hydroperoxide Reductase ◽  
Alkyl Hydroperoxide

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.

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