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4n3m

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

Structural highlights

4n3m is a 1 chain structure with sequence from Aspergillus flavus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Hybrid , Neutron Diffraction , X-ray diffraction, Resolution 1.919Å
Ligands:	, , , ,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

URIC_ASPFL Catalyzes the oxidation of uric acid to 5-hydroxyisourate, which is further processed to form (S)-allantoin.

Publication Abstract from PubMed

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.

The neutron structure of urate oxidase resolves a long-standing mechanistic conundrum and reveals unexpected changes in protonation.,Oksanen E, Blakeley MP, El-Hajji M, Ryde U, Budayova-Spano M PLoS One. 2014 Jan 23;9(1):e86651. doi: 10.1371/journal.pone.0086651. eCollection, 2014 Jan 23. PMID:24466188^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Oksanen E, Blakeley MP, El-Hajji M, Ryde U, Budayova-Spano M. The neutron structure of urate oxidase resolves a long-standing mechanistic conundrum and reveals unexpected changes in protonation. PLoS One. 2014 Jan 23;9(1):e86651. doi: 10.1371/journal.pone.0086651. eCollection, 2014 Jan 23. PMID:24466188 doi:http://dx.doi.org/10.1371/journal.pone.0086651