InterPro domain: IPR002042

Uricase ( 1.7.3.3 ) (urate oxidase) [ 1 ] is the peroxisomal enzyme responsiblefor the degradation of urate into allantoin: Urate + O ₂ + H ₂ O = 5-hydroxyisourate + H ₂ O ₂ Some species, like primates and birds, have lost the gene for uricase and are therefore unable to degrade urate [ 2 ]. Uricase is a protein of 300 to 400 amino acids, its sequence is well conserved.It is mainly localised in the liver, where it forms a large electron-dense paracrystalline core in many peroxisomes [ 3 ].The enzyme exists as a tetramer of identical subunits, each containing a possible type 2 copper-binding site [ 4 ]. In legumes, 2 forms of uricase are found: in the roots, the tetrameric form; and, in the uninfected cells of root nodules, a monomeric form, which plays animportant role in nitrogen-fixation [ 4 ].

1. Cloning and sequence analysis of cDNA for rat liver uricase. J. Biol. Chem. 263, 16677-81
2. Urate oxidase: primary structure and evolutionary implications. Proc. Natl. Acad. Sci. U.S.A. 86, 9412-6
3. Organization of rat uricase chromosomal gene differs greatly from that of the corresponding plant gene. FEBS Lett. 264, 156-8
4. Primary structure of the soybean nodulin-35 gene encoding uricase II localized in the peroxisomes of uninfected cells of nodules. Proc. Natl. Acad. Sci. U.S.A. 82, 5040-5044