Catalase-like Oxygen Production by Horseradish Peroxidase Must Predominantly Be an Enzyme-Catalyzed Reaction

When hydrogen peroxide (H2O2) was provided as the only substrate for horseradish peroxidase C (HRP-C) the catalase-like emission of oxygen gas was observed. The reaction was favored at neutral compared to acidic pH. Addition of the superoxide radical scavengers tetranitromethane (TNM) or superoxide...

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Bibliographic Details
Published in:Archives of biochemistry and biophysics 2001-08, Vol.392 (2), p.295-302
Main Authors: Hiner, Alexander N.P., Hernández-Ruiz, Josefa, Williams, Gareth A., Arnao, Marino B., Garcí́a-Cánovas, Francisco, Acosta, Manuel
Format: Article
Language:English
Subjects:
Arginine - chemistry
catalase
Catalase - chemistry
Catalase - metabolism
Catalysis
Computer Simulation
Escherichia coli - metabolism
Free Radical Scavengers - metabolism
Histidine - chemistry
Horseradish Peroxidase - metabolism
hydrogen peroxide
Hydrogen Peroxide - metabolism
Hydrogen-Ion Concentration
inactivation
Ions
Kinetics
Manganese - metabolism
Models, Chemical
Mutagenesis, Site-Directed
oxygen
Oxygen - metabolism
peroxidase
site-directed mutants
superoxide
Superoxide Dismutase - metabolism
superoxide scavengers
Tetranitromethane - metabolism
Time Factors
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Summary:When hydrogen peroxide (H2O2) was provided as the only substrate for horseradish peroxidase C (HRP-C) the catalase-like emission of oxygen gas was observed. The reaction was favored at neutral compared to acidic pH. Addition of the superoxide radical scavengers tetranitromethane (TNM) or superoxide dismutase (SOD) increased activity. TNM's effect was concentration dependent but SOD's was not, indicating that only some of the superoxide generated was released into solution. Manganous ions (Mn2+) react with superoxide radicals to regenerate H2O2 but not oxygen; when added to the reaction medium oxygen production was reduced but not abolished. The effect was essentially concentration independent, suggesting that most oxygen was produced enzymatically and not by chemical disproportionation of superoxide. The catalase-like activities of some site-directed mutants of HRP-C suggest that active site residues histidine 42 and arginine 38 are influential in determining this activity. A clear correlation also existed between catalase activity and the enzymes' resistance to inactivation by H2O2. Computer simulation of a reaction scheme that included catalase-like activity agreed well with experimental data.
ISSN:0003-9861
1096-0384
DOI:10.1006/abbi.2001.2460