Reaction participants Show >> << Hide
- Name help_outline UDP-α-D-glucuronate Identifier CHEBI:58052 Charge -3 Formula C15H19N2O18P2 InChIKeyhelp_outline HDYANYHVCAPMJV-LXQIFKJMSA-K SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])(=O)OP([O-])(=O)O[C@H]2O[C@@H]([C@@H](O)[C@H](O)[C@H]2O)C([O-])=O)O[C@H]([C@@H]1O)n1ccc(=O)[nH]c1=O 2D coordinates Mol file for the small molecule Search links Involved in 107 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 6,418 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline D-glucuronate Identifier CHEBI:58720 (Beilstein: 4189951) help_outline Charge -1 Formula C6H9O7 InChIKeyhelp_outline AEMOLEFTQBMNLQ-AQKNRBDQSA-M SMILEShelp_outline OC1O[C@@H]([C@@H](O)[C@H](O)[C@H]1O)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 22 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline UDP Identifier CHEBI:58223 Charge -3 Formula C9H11N2O12P2 InChIKeyhelp_outline XCCTYIAWTASOJW-XVFCMESISA-K SMILEShelp_outline O[C@@H]1[C@@H](COP([O-])(=O)OP([O-])([O-])=O)O[C@H]([C@@H]1O)n1ccc(=O)[nH]c1=O 2D coordinates Mol file for the small molecule Search links Involved in 629 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline H+ Identifier CHEBI:15378 Charge 1 Formula H InChIKeyhelp_outline GPRLSGONYQIRFK-UHFFFAOYSA-N SMILEShelp_outline [H+] 2D coordinates Mol file for the small molecule Search links Involved in 9,836 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
| RHEA:26073 | RHEA:26074 | RHEA:26075 | RHEA:26076 | |
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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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Glucuronate, the precursor of vitamin C, is directly formed from UDP-glucuronate in liver.
Linster C.L., Van Schaftingen E.
The conversion of UDP-glucuronate to glucuronate, usually thought to proceed by way of glucuronate 1-phosphate, is a site for short-term regulation of vitamin C synthesis by metyrapone and other xenobiotics in isolated rat hepatocytes. Our purpose was to explore the mechanism of this effect in cel ... >> More
The conversion of UDP-glucuronate to glucuronate, usually thought to proceed by way of glucuronate 1-phosphate, is a site for short-term regulation of vitamin C synthesis by metyrapone and other xenobiotics in isolated rat hepatocytes. Our purpose was to explore the mechanism of this effect in cell-free systems. Metyrapone and other xenobiotics stimulated, by approximately threefold, the formation of glucuronate from UDP-glucuronate in liver extracts enriched with ATP-Mg, but did not affect the formation of glucuronate 1-phosphate from UDP-glucuronate or the conversion of glucuronate 1-phosphate to glucuronate. This and other data indicated that glucuronate 1-phosphate is not an intermediate in glucuronate formation from UDP-glucuronate, suggesting that this reaction is catalysed by a 'UDP-glucuronidase'. UDP-glucuronidase was present mainly in the microsomal fraction, where its activity was stimulated by UDP-N-acetylglucosamine, known to stimulate UDP-glucuronosyltransferases by enhancing the transport of UDP-glucuronate across the endoplasmic reticulum membrane. UDP-glucuronidase and UDP-glucuronosyltransferases displayed similar sensitivities to various detergents, which stimulated at low concentrations and generally inhibited at higher concentrations. Substrates of glucuronidation inhibited UDP-glucuronidase activity, suggesting that the latter is contributed by UDP-glucuronosyltransferase(s). Inhibitors of beta-glucuronidase and esterases did not affect the formation of glucuronate, arguing against the involvement of a glucuronidation-deglucuronidation cycle. The sensitivity of UDP-glucuronidase to metyrapone and other stimulatory xenobiotics was lost in washed microsomes, even in the presence of ATP-Mg, but it could be restored by adding a heated liver high-speed supernatant or CoASH. In conclusion, glucuronate formation in liver is catalysed by a UDP-glucuronidase which is closely related to UDP-glucuronosyltransferases. Metyrapone and other xenobiotics stimulate UDP-glucuronidase by antagonizing the inhibition exerted, presumably indirectly, by a combination of ATP-Mg and CoASH. << Less
Comments
Reaction catalyzed by UDP-glucuronidase.