Identification and structural characterization of a transient Radical Species in the Uricase Reaction Mechanism

Uricase catalyzes the oxidation of urate to form allantoin, carbon dioxide and hydrogen peroxide. In this article, we demonstrate for the first time the presence of a radical intermediate involved in the reaction mechanism. Such radical species was entrapped using 5-diethoxyphosphoryl-5-methyl-1-pyrroline N-oxide as spin trap and the relative adduct was detected by electron paramagnetic resonance (EPR) technique. A structure of such radical (5-hydroperoxy isourate) is proposed, through chemical results and density functional theory calculations of the EPR coupling constants.