title: EPR spin trapping of a radical intermediate in the urate oxidase reaction.
abstract: 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.
authors.affiliation: Dipartimento di Chimica, Scienze Endocrino-Metaboliche e Biochimica, Università di Siena, Siena, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Busi
authors.forename: L
authors.initials: L
authors.lastname: Terzuoli
authors.forename: R
authors.initials: R
authors.lastname: Basosi
authors.forename: B
authors.initials: B
authors.lastname: Porcelli
authors.forename: E
authors.initials: E
authors.lastname: Marinello
mesh_terms: D000818:Animals; D001407:Bacillus / Q000378:metabolism; D002175:Candida / Q000378:metabolism; D002384:Catalysis; D003497:Cyclic N-Oxides / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000379:methods*; D005609:Free Radicals; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism; D013113:Spin Labels; D019097:Spin Trapping; D013552:Swine; D014503:Urate Oxidase / Q000737:chemistry*; D014527:Uric Acid / Q000097:blood / Q000737:chemistry
chemical_list: D003497:Cyclic N-Oxides; D005609:Free Radicals; D013113:Spin Labels; C098505:5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide; D014527:Uric Acid; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D014503:Urate Oxidase; D010100:Oxygen