EPR Spin Trapping of a Radical Intermediate in the Urate Oxidase Reaction

Urate oxidase, or uricase (EC 1.7.3.3), is a peroxisomal enzyme that catalyses the oxidation of uric acid to allantoin. The chemical mechanism of the urate oxidase reaction has not been clearly established, but the involvement of radical intermediates was hypothesised. In this study EPR spectroscopy...

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Bibliographic Details
Published in:Nucleosides, nucleotides & nucleic acids nucleotides & nucleic acids, 2004-10, Vol.23 (8-9), p.1131-1134
Main Authors: Busi, E., Terzuoli, L., Basosi, R., Porcelli, B., Marinello, E.
Format: Article
Language:English
Subjects:
Animals
Bacillus
Bacillus - metabolism
Candida
Candida - metabolism
Catalysis
Cyclic N-Oxides - chemistry
Electron Spin Resonance Spectroscopy - methods
Free Radicals
Humans
Hydrogen Peroxide - chemistry
Hydroxyl Radical
Oxidation
Oxygen - chemistry
Oxygen - metabolism
Radical intermediate
Spin Labels
Spin Trapping
Spin-trap
Swine
Urate Oxidase - chemistry
Uric acid
Uric Acid - blood
Uric Acid - chemistry
Uricase
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Summary:Urate oxidase, or uricase (EC 1.7.3.3), is a peroxisomal enzyme that catalyses the oxidation of uric acid to allantoin. The chemical mechanism of the urate oxidase reaction has not been clearly established, but the involvement of radical intermediates was hypothesised. In this study EPR spectroscopy by spin trapping of radical intermediates has been used in order to demonstrate the eventual presence of radical transient urate species. The oxidation reaction of uric acid by several uricases (Porcine Liver, Bacillus Fastidiosus, Candida Utilitis) was performed in the presence of 5-diethoxyphosphoryl-5-methyl-pyrroline-N-oxide (DEPMPO) as spin trap. DEPMPO was added to reaction mixture and a radical adduct was observed in all cases. Therefore, for the first time, the presence of a radical intermediate in the uricase reaction was experimentally proved.
ISSN:1525-7770
1532-2335
DOI:10.1081/NCN-200027390