4N3M: Joint neutron/X-ray structure of urate oxidase in complex with 8-azaxanthine

Urate oxidase transforms uric acid to 5-hydroxyisourate without the help of cofactors, but the catalytic mechanism has remained enigmatic, as the protonation state of the substrate could not be reliably deduced. We have determined the neutron structure of urate oxidase, providing unique information on the proton positions. A neutron crystal structure inhibited by a chloride anion at 2.3 A resolution shows that the substrate is in fact 8-hydroxyxanthine, the enol tautomer of urate. We have also determined the neutron structure of the complex with the inhibitor 8-azaxanthine at 1.9 A resolution, showing the protonation states of the K10-T57-H256 catalytic triad. Together with X-ray data and quantum chemical calculations, these structures allow us to identify the site of the initial substrate protonation and elucidate why the enzyme is inhibited by a chloride anion.
PDB ID: 4N3MDownload
MMDB ID: 117300
PDB Deposition Date: 2013/10/7
Updated in MMDB: 2018/06
Experimental Method:
neutron diffraction; x-ray diffraction
Resolution: 1.904  Å
Source Organism:
Similar Structures:
Biological Unit for 4N3M: tetrameric; determined by author and by software (PISA)
Molecular Components in 4N3M
Label Count Molecule
Proteins (4 molecules)
Molecule annotation
Chemicals (12 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB