Antioxidant Capacity of Poly(Ethylene Glycol) (PEG) as Protection Mechanism Against Hydrogen Peroxide Inactivation of Peroxidases

The ability of poly(ethylene glycol) (PEG) to protect enzymatic peroxidase activity was determined for horseradish peroxidase (HRP), versatile peroxidase (VP), commercial Coprinus peroxidase (BP), and chloroperoxidase (CPO). The operational stability measured as the total turnover number was determi...

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Bibliographic Details
Published in:Applied biochemistry and biotechnology 2015-11, Vol.177 (6), p.1364-1373
Main Authors: Juarez-Moreno, Karla, Ayala, Marcela, Vazquez-Duhalt, Rafael
Format: Article
Language:English
Subjects:
antioxidant activity
Antioxidants
Biochemistry
Biotechnology
Catalysis
Chemistry
Chemistry and Materials Science
Coprinus
Enzymes
ethylene glycol
Hydrogen peroxide
Hydrogen Peroxide - chemistry
Inactivation
Oxidation
Oxidation-Reduction
peroxidase
Peroxidase - chemistry
Plant Proteins - chemistry
Polyethylene glycol
Polyethylene Glycols - chemistry
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Summary:The ability of poly(ethylene glycol) (PEG) to protect enzymatic peroxidase activity was determined for horseradish peroxidase (HRP), versatile peroxidase (VP), commercial Coprinus peroxidase (BP), and chloroperoxidase (CPO). The operational stability measured as the total turnover number was determined for the four peroxidases. The presence of PEG significantly increased the operational stability of VP and HRP up to 123 and 195 %, respectively, and dramatically increased the total turnover number of BP up to 597 %. Chloroperoxidase was not protected by PEG, which may be due to the different oxidation mechanism, in which the oxidation is mediated by hypochlorous ion instead of free radicals as in the other peroxidases. The presence of PEG does not protect the enzyme when incubated only in the presence of H₂O₂ without reducing substrate. The catalytic constants (k cₐₜ) are insensitive to the presence of PEG, suggesting that the protection mechanism is not due to a competition between the PEG and the substrate as electron donors. On the other hand, PEG showed to have a significant antioxidant capacity. Thus, we conclude that the protection mechanism for peroxidases of PEG is based in its antioxidant capacity with which it is able scavenge or drain radicals that are harmful to the protein.
ISSN:0273-2289
1559-0291
DOI:10.1007/s12010-015-1820-y