Urate oxidase is an essential enzyme involved in purine degradation pathway. It is responsible for the conversion of uric acid to allantoin, thus catalysing the oxidative ring opening of the purine ring in the degradative pathway.
The enzyme is lacking in humans, it can therefore be used as a protein drug to treat / reduce toxic uric acid accumulation.
The active enzyme is a homotetramer, each dimer can be considered as a porin-like structure, with the 16 antiparallel strands superimposed in a reverse handed manner on those from a porin, the helices taking the place of the membrane. The enzyme was originally thought to require a copper cofactor, however it has since been shown that is doesn't require a cofactor [PMID:12680763].
The enzyme is a member of a family of proteins with multimeric barrels face to face related by two-fold symmetry, proposed to be a new family of tunnel-shaped proteins.