Enzymes
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- Name help_outline 6,8-dihydroxypurine Identifier CHEBI:165832 (CAS: 13231-00-0) help_outline Charge 0 Formula C5H4N4O2 InChIKeyhelp_outline BYUOBSUZYQAFJM-UHFFFAOYSA-N SMILEShelp_outline O=C1NC=NC=2NC(=O)NC21 2D coordinates Mol file for the small molecule Search links Involved in 1 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline O2 Identifier CHEBI:15379 (CAS: 7782-44-7) help_outline Charge 0 Formula O2 InChIKeyhelp_outline MYMOFIZGZYHOMD-UHFFFAOYSA-N SMILEShelp_outline O=O 2D coordinates Mol file for the small molecule Search links Involved in 2,903 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O Identifier CHEBI:15377 (CAS: 7732-18-5) help_outline Charge 0 Formula H2O InChIKeyhelp_outline XLYOFNOQVPJJNP-UHFFFAOYSA-N SMILEShelp_outline [H]O[H] 2D coordinates Mol file for the small molecule Search links Involved in 6,648 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline urate Identifier CHEBI:17775 (CAS: 69-93-2) help_outline Charge 0 Formula C5H4N4O3 InChIKeyhelp_outline LEHOTFFKMJEONL-UHFFFAOYSA-N SMILEShelp_outline O=c1[nH]c2[nH]c(=O)[nH]c(=O)c2[nH]1 2D coordinates Mol file for the small molecule Search links Involved in 21 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H2O2 Identifier CHEBI:16240 (CAS: 7722-84-1) help_outline Charge 0 Formula H2O2 InChIKeyhelp_outline MHAJPDPJQMAIIY-UHFFFAOYSA-N SMILEShelp_outline [H]OO[H] 2D coordinates Mol file for the small molecule Search links Involved in 468 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:68028 | RHEA:68029 | RHEA:68030 | RHEA:68031 | |
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| Reaction direction help_outline | undefined | left-to-right | right-to-left | bidirectional |
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Publications
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Substrate orientation and catalytic specificity in the action of xanthine oxidase: the sequential hydroxylation of hypoxanthine to uric acid.
Cao H., Pauff J.M., Hille R.
Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp(2)-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 A resolution and the chemoth ... >> More
Xanthine oxidase is a molybdenum-containing enzyme catalyzing the hydroxylation of a sp(2)-hybridized carbon in a broad range of aromatic heterocycles and aldehydes. Crystal structures of the bovine enzyme in complex with the physiological substrate hypoxanthine at 1.8 A resolution and the chemotherapeutic agent 6-mercaptopurine at 2.6 A resolution have been determined, showing in each case two alternate orientations of substrate in the two active sites of the crystallographic asymmetric unit. One orientation is such that it is expected to yield hydroxylation at C-2 of substrate, yielding xanthine. The other suggests hydroxylation at C-8 to give 6,8-dihydroxypurine, a putative product not previously thought to be generated by the enzyme. Kinetic experiments demonstrate that >98% of hypoxanthine is hydroxylated at C-2 rather than C-8, indicating that the second crystallographically observed orientation is significantly less catalytically effective than the former. Theoretical calculations suggest that enzyme selectivity for the C-2 over C-8 of hypoxanthine is largely due to differences in the intrinsic reactivity of the two sites. For the orientation of hypoxanthine with C-2 proximal to the molybdenum center, the disposition of substrate in the active site is such that Arg(880) and Glu(802), previous shown to be catalytically important for the conversion of xanthine to uric acid, play similar roles in hydroxylation at C-2 as at C-8. Contrary to the literature, we find that 6,8-dihydroxypurine is effectively converted to uric acid by xanthine oxidase. << Less
J Biol Chem 285:28044-28053(2010) [PubMed] [EuropePMC]
This publication is cited by 2 other entries.