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Crystal Structure of Bovine Milk Xanthine Dehydrogenase FYX-051 bound form
Structural highlights
FunctionXDH_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. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMolybdenum is widely distributed in biology and is usually found as a mononuclear metal center in the active sites of many enzymes catalyzing oxygen atom transfer. The molybdenum hydroxylases are distinct from other biological systems catalyzing hydroxylation reactions in that the oxygen atom incorporated into the product is derived from water rather than molecular oxygen. Here, we present the crystal structure of the key intermediate in the hydroxylation reaction of xanthine oxidoreductase with a slow substrate, in which the carbon-oxygen bond of the product is formed, yet the product remains complexed to the molybdenum. This intermediate displays a stable broad charge-transfer band at approximately 640 nm. The crystal structure of the complex indicates that the catalytically labile Mo-OH oxygen has formed a bond with a carbon atom of the substrate. In addition, the MoS group of the oxidized enzyme has become protonated to afford Mo-SH on reduction of the molybdenum center. In contrast to previous assignments, we find this last ligand at an equatorial position in the square-pyramidal metal coordination sphere, not the apical position. A water molecule usually seen in the active site of the enzyme is absent in the present structure, which probably accounts for the stability of this intermediate toward ligand displacement by hydroxide. The crystal structure of xanthine oxidoreductase during catalysis: implications for reaction mechanism and enzyme inhibition.,Okamoto K, Matsumoto K, Hille R, Eger BT, Pai EF, Nishino T Proc Natl Acad Sci U S A. 2004 May 25;101(21):7931-6. Epub 2004 May 17. PMID:15148401[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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