X-ray, ESR, and quantum mechanics studies unravel a spin well in the cofactor-less urate oxidase.

Urate oxidase (EC 1.7.3.

Near-atomic resolution structures of urate oxidase complexed with its substrate and analogues: the protonation state of the ligand.

Urate oxidase (uricase; EC 1.7.3.

Structural analysis of urate oxidase in complex with its natural substrate inhibited by cyanide: mechanistic implications.

Background: Urate oxidase (EC 1.7.3.

Oxygen pressurized X-ray crystallography: probing the dioxygen binding site in cofactorless urate oxidase and implications for its catalytic mechanism.

The localization of dioxygen sites in oxygen-binding proteins is a nontrivial experimental task and is often suggested through indirect methods such as using xenon or halide anions as oxygen probes. In this study, a straightforward method based on x-ray crystallography under high pressure of pure oxygen has been developed. An application is given on urate oxidase (UOX), a cofactorless enzyme that catalyzes the oxidation of uric acid to 5-hydroxyisourate in the presence of dioxygen.

Recapture of [S]-allantoin, the product of the two-step degradation of uric acid, by urate oxidase.

Urate oxidase from Aspergillus flavus catalyzes the degradation of uric acid to [S]-allantoin through 5-hydroxyisourate as a metastable intermediate. The second degradation step is thought either catalyzed by another specific enzyme, or spontaneous. The structure of the enzyme was known at high resolution by X-ray diffraction of I222 crystals complexed with a purine-type inhibitor (8-azaxanthin).