PDBsum entry 4oqc

Oxygen binding

PDB id: 4oqc

Contents

Protein chain

296 a.a.

Ligands

AZI ×2

Metals

_NA

Waters ×242

PDB id:

4oqc

Name:

Oxygen binding

Title:

Urate oxidase co-crystallized with azide

Structure:

Uricase. Chain: a. Fragment: unp residues 2-302. Synonym: urate oxidase. Engineered: yes

Source:

Aspergillus flavus. Organism_taxid: 5059. Gene: uaz, uox. Expressed in: saccharomyces cerevisiae. Expression_system_taxid: 4932

Resolution:

1.30Å R-factor: 0.188

Authors:

N.Colloc'H,T.Prange

Key ref:

L.Gabison et al. (2014). Azide inhibition of urate oxidase. Acta Crystallogr F Struct Biol Commun, 70, 896-902. PubMed id: 25005084 DOI: 10.1107/S2053230X14011753

Date:

08-Feb-14 Release date: 24-Dec-14

Protein chain

Q00511  (URIC_ASPFL) -  Uricase from Aspergillus flavus

Seq: 302 a.a.

Struc: 295 a.a.

Enzyme reactions

• Enzyme class: E.C.1.7.3.3 - factor independent urate hydroxylase.
• Pathway: AMP Catabolism
• Reaction: urate + O2 + H2O = 5-hydroxyisourate + H2O2
• Cofactor: Copper

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1107/S2053230X14011753

Acta Crystallogr F Struct Biol Commun 70:896-902 (2014)

PubMed id: 25005084

Azide inhibition of urate oxidase.

L.Gabison, N.Colloc'h, T.Prangé.

ABSTRACT

The inhibition of urate oxidase (UOX) by azide was investigated by X-ray diffraction techniques and compared with cyanide inhibition. Two well characterized sites for reagents are present in the enzyme: the dioxygen site and the substrate-binding site. To examine the selectivity of these sites towards azide inhibition, several crystallization conditions were developed. UOX was co-crystallized with azide (N3) in the presence or absence of either uric acid (UA, the natural substrate) or 8-azaxanthine (8AZA, a competitive inhibitor). In a second set of experiments, previously grown orthorhombic crystals of the UOX-UA or UOX-8AZA complexes were soaked in sodium azide solutions. In a third set of experiments, orthorhombic crystals of UOX with the exchangeable ligand 8-nitroxanthine (8NXN) were soaked in a solution containing uric acid and azide simultaneously (competitive soaking). In all assays, the soaking periods were either short (a few hours) or long (one or two months). These different experimental conditions showed that one or other of the sites, or the two sites together, could be inhibited. This also demonstrated that azide not only competes with dioxygen as cyanide does but also competes with the substrate for its enzymatic site. A model in agreement with experimental data would be an azide in equilibrium between two sites, kinetically in favour of the dioxygen site and thermodynamically in favour of the substrate-binding site.