|1fo4, resolution 2.10Å ()|
|Ligands:||, , , , , ,|
CRYSTAL STRUCTURE OF XANTHINE DEHYDROGENASE ISOLATED FROM BOVINE MILK
Mammalian xanthine oxidoreductases, which catalyze the last two steps in the formation of urate, are synthesized as the dehydrogenase form xanthine dehydrogenase (XDH) but can be readily converted to the oxidase form xanthine oxidase (XO) by oxidation of sulfhydryl residues or by proteolysis. Here, we present the crystal structure of the dimeric (M(r), 290,000) bovine milk XDH at 2.1-A resolution and XO at 2.5-A resolution and describe the major changes that occur on the proteolytic transformation of XDH to the XO form. Each molecule is composed of an N-terminal 20-kDa domain containing two iron sulfur centers, a central 40-kDa flavin adenine dinucleotide domain, and a C-terminal 85-kDa molybdopterin-binding domain with the four redox centers aligned in an almost linear fashion. Cleavage of surface-exposed loops of XDH causes major structural rearrangement of another loop close to the flavin ring (Gln 423Lys 433). This movement partially blocks access of the NAD substrate to the flavin adenine dinucleotide cofactor and changes the electrostatic environment of the active site, reflecting the switch of substrate specificity observed for the two forms of this enzyme.
Crystal structures of bovine milk xanthine dehydrogenase and xanthine oxidase: structure-based mechanism of conversion., Enroth C, Eger BT, Okamoto K, Nishino T, Nishino T, Pai EF, Proc Natl Acad Sci U S A. 2000 Sep 26;97(20):10723-8. PMID:11005854
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
About this Structure
1fo4 is a 2 chain structure with sequence from Bos taurus. The September 2009 RCSB PDB Molecule of the Month feature on Xanthine Oxidoreductase by David Goodsell is 10.2210/rcsb_pdb/mom_2009_9. Full crystallographic information is available from OCA.
- Enroth C, Eger BT, Okamoto K, Nishino T, Nishino T, Pai EF. Crystal structures of bovine milk xanthine dehydrogenase and xanthine oxidase: structure-based mechanism of conversion. Proc Natl Acad Sci U S A. 2000 Sep 26;97(20):10723-8. PMID:11005854