3BK8: Urate Oxidase Aza-xanthine Complex In Cyanide

Citation:
Abstract
BACKGROUND: Urate oxidase (EC 1.7.3.3 or UOX) catalyzes the conversion of uric acid and gaseous molecular oxygen to 5-hydroxyisourate and hydrogen peroxide, in the absence of cofactor or particular metal cation. The functional enzyme is a homo-tetramer with four active sites located at dimeric interfaces. RESULTS: The catalytic mechanism was investigated through a ternary complex formed between the enzyme, uric acid, and cyanide that stabilizes an intermediate state of the reaction. When uric acid is replaced by a competitive inhibitor, no complex with cyanide is formed. CONCLUSION: The X-ray structure of this compulsory ternary complex led to a number of mechanistic evidences that support a sequential mechanism in which the two reagents, dioxygen and a water molecule, process through a common site located 3.3 A above the mean plane of the ligand. This site is built by the side chains of Asn 254, and Thr 57, two conserved residues belonging to two different subunits of the homo-tetramer. The absence of a ternary complex between the enzyme, a competitive inhibitor, and cyanide suggests that cyanide inhibits the hydroxylation step of the reaction, after the initial formation of a hydroperoxyde type intermediate.
PDB ID: 3BK8Download
MMDB ID: 66007
PDB Deposition Date: 2007/12/6
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.6  Å
Source Organism:
Similar Structures:
Biological Unit for 3BK8: tetrameric; determined by author and by software (PISA)
Molecular Components in 3BK8
Label Count Molecule
Proteins (4 molecules)
4
Uricase
Molecule annotation
Chemicals (8 molecules)
1
4
2
4
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.