3sr6

Crystal Structure of Reduced Bovine Xanthine Oxidase in Complex with Arsenite

spinqualitylabelsall models 3sr6, resolution 2.10Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3sr6 is a 6 chain structure with sequence from Bos taurus. This structure supersedes the now removed PDB entry 3rca. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: FAD, FES, MTE, RMO Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [XDH_BOVIN] Key enzyme in purine degradation. Catalyzes the oxidation of hypoxanthine to xanthine. Catalyzes the oxidation of xanthine to uric acid. Contributes to the generation of reactive oxygen species. Publication Abstract from PubMed Xanthine oxidoreductase is a molybdenum-containing enzyme that catalyzes the hydroxylation reaction of sp(2)-hybridized carbon centers of a variety of substrates, including purines, aldehydes, and other heterocyclic compounds. The complex of arsenite-inhibited xanthine oxidase has been characterized previously by UV-vis, electron paramagnetic resonance, and X-ray absorption spectroscopy (XAS), and the catalytically essential sulfido ligand of the square-pyrimidal molybdenum center has been suggested to be involved in arsenite binding through either a mu-sulfido,mu-oxo double bridge or a single mu-sulfido bridge. However, this is contrary to the crystallographically observed single mu-oxo bridge between molybdenum and arsenic in the desulfo form of aldehyde oxidoreductase from Desulfovibrio gigas (an enzyme closely related to xanthine oxidase), whose molybdenum center has an oxo ligand replacing the catalytically essential sulfur, as seen in the functional form of xanthine oxidase. Here we use X-ray crystallography to characterize the molybdenum center of arsenite-inhibited xanthine oxidase and solve the structures of the oxidized and reduced inhibition complexes at 1.82 and 2.11 A resolution, respectively. We observe mu-sulfido,mu-oxo double bridges between molybdenum and arsenic in the active sites of both complexes. Arsenic is four-coordinate with a distorted trigonal-pyramidal geometry in the oxidized complex and three-coordinate with a distorted trigonal-planar geometry in the reduced complex. The doubly bridged binding mode is in agreement with previous XAS data indicating that the catalytically essential sulfur is also essential for the high affinity of reduced xanthine oxidoreductase for arsenite. X-ray crystal structure of arsenite-inhibited xanthine oxidase: mu-sulfido,mu-oxo double bridge between molybdenum and arsenic in the active site.,Cao H, Hall J, Hille R J Am Chem Soc. 2011 Aug 17;133(32):12414-7. Epub 2011 Jul 21. PMID:21761899 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Xanthine dehydrogenase

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