3ETR: Crystal Structure Of Xanthine Oxidase In Complex With Lumazine

Citation:
Abstract
Xanthine oxidoreductase is a ubiquitous cytoplasmic protein that catalyzes the final two steps in purine catabolism. We have previously investigated the catalytic mechanism of the enzyme by rapid reaction kinetics and x-ray crystallography using the poor substrate 2-hydroxy-6-methylpurine, focusing our attention on the orientation of substrate in the active site and the role of Arg-880 in catalysis. Here we report additional crystal structures of as-isolated, functional xanthine oxidase in the course of reaction with the pterin substrate lumazine at 2.2 A resolution and of the nonfunctional desulfo form of the enzyme in complex with xanthine at 2.6 A resolution. In both cases the orientation of substrate is such that the pyrimidine subnucleus is oriented opposite to that seen with the slow substrate 2-hydroxy-6-methylpurine. The mechanistic implications as to how the ensemble of active site functional groups in the active site work to accelerate reaction rate are discussed.
PDB ID: 3ETRDownload
MMDB ID: 69312
PDB Deposition Date: 2008/10/8
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 2.2  Å
Source Organism:
Similar Structures:
Biological Unit for 3ETR: hexameric; determined by author and by software (PISA)
Molecular Components in 3ETR
Label Count Molecule
Proteins (6 molecules)
2
Xanthine Dehydrogenase/oxidase(Gene symbol: XDH)
Molecule annotation
2
Xanthine Dehydrogenase/oxidase(Gene symbol: XDH)
Molecule annotation
2
Xanthine Dehydrogenase/oxidase(Gene symbol: XDH)
Molecule annotation
Chemicals (13 molecules)
1
4
2
2
3
2
4
2
5
2
6
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.