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Urate oxidase from the rust Puccinia recondita is a heterotetramer with two different-sized monomers
Miguel Aguilar1, Paolo Montalbini, Manuel Pineda
1Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, Campus Rabanales, Edificio C-6, 1 Planta, 14071-Córdoba, Spain.
Abstract:
Uricase (urate: oxygen oxidoreductase; EC 1.7.3.3) from the rust Puccinia recondita was purified to electrophoretic homogeneity. Preparations with a specific activity of 8.4 U/mg were used for characterization of the enzyme, which showed a strong similarity to other plant and fungal urate oxidases. The enzyme had a pH optimum of 9.0, a K(m) of 35 microM for urate, and it was inhibited only by oxonate and xanthine. A molecular mass of 152 kDa was estimated for the native protein. SDS-PAGE analysis revealed a striking difference to most urate oxidases, since two different-sized subunits were detected. These results suggest that P. recondita uricase is a tetramer with two types of subunits.