Enzymes
UniProtKB help_outline | 5,124 proteins |
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- Name help_outline 6-(2-amino-2-carboxyethyl)-7,8-dioxo-1,2,3,4,7,8-hexahydroquinoline-2,4-dicarboxylate Identifier CHEBI:58778 Charge -2 Formula C14H12N2O8 InChIKeyhelp_outline UMYDVEVERVKIFT-UHFFFAOYSA-L SMILEShelp_outline [NH3+]C(CC1=CC2=C(NC(CC2C([O-])=O)C([O-])=O)C(=O)C1=O)C([O-])=O 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 2,779 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
- Name help_outline pyrroloquinoline quinone Identifier CHEBI:58442 Charge -3 Formula C14H3N2O8 InChIKeyhelp_outline MMXZSJMASHPLLR-UHFFFAOYSA-K SMILEShelp_outline [O-]C(=O)c1cc(C([O-])=O)c-2c(n1)C(=O)C(=O)c1cc([nH]c-21)C([O-])=O 2D coordinates Mol file for the small molecule Search links Involved in 4 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 452 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 6,337 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 9,717 reaction(s) Find molecules that contain or resemble this structure Find proteins in UniProtKB for this molecule
Cross-references
RHEA:10692 | RHEA:10693 | RHEA:10694 | RHEA:10695 | |
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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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The structure of a biosynthetic intermediate of pyrroloquinoline quinone (PQQ) and elucidation of the final step of PQQ biosynthesis.
Magnusson O.T., Toyama H., Saeki M., Schwarzenbacher R., Klinman J.P.
Pyrroloquinoline quinone (PQQ) is a tricyclic o-quinone, which serves as a cofactor in several enzyme-catalyzed redox reactions in certain bacteria. PQQ is also important for human health, and its role as a vitamin in mammals has recently been suggested. Although much is known about the function o ... >> More
Pyrroloquinoline quinone (PQQ) is a tricyclic o-quinone, which serves as a cofactor in several enzyme-catalyzed redox reactions in certain bacteria. PQQ is also important for human health, and its role as a vitamin in mammals has recently been suggested. Although much is known about the function of enzymes that use PQQ as cofactor, relatively little is known about the biosynthesis of this coenzyme. Six gene products in Klebsiella pneumoniae (PqqA-F) are involved in PQQ biosynthesis, and PqqC has been shown to catalyze the last step in the pathway. The chemical structure of the substrate for PqqC has remained elusive and has hampered our understanding of the nature of this reaction. In this report we describe the purification and structure of the substrate as deduced by a number of spectroscopic and chemical methods. The substrate is 3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic acid-a fully reduced derivative of PQQ, which has not undergone ring cyclization. These results show that PqqC catalyzes a novel reaction, which involves ring closure and an amazing eight-electron oxidation of the substrate. << Less
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Quinone biogenesis: structure and mechanism of PqqC, the final catalyst in the production of pyrroloquinoline quinone.
Magnusson O.T., Toyama H., Saeki M., Rojas A., Reed J.C., Liddington R.C., Klinman J.P., Schwarzenbacher R.
The biosynthesis of pyrroloquinoline quinone (PQQ), a vitamin and redox cofactor of quinoprotein dehydrogenases, is facilitated by an unknown pathway that requires the expression of six genes, pqqA to -F. PqqC, the protein encoded by pqqC, catalyzes the final step in the pathway in a reaction that ... >> More
The biosynthesis of pyrroloquinoline quinone (PQQ), a vitamin and redox cofactor of quinoprotein dehydrogenases, is facilitated by an unknown pathway that requires the expression of six genes, pqqA to -F. PqqC, the protein encoded by pqqC, catalyzes the final step in the pathway in a reaction that involves ring cyclization and eight-electron oxidation of 3a-(2-amino-2-carboxyethyl)-4,5-dioxo-4,5,6,7,8,9-hexahydroquinoline-7,9-dicarboxylic-acid to PQQ. Herein, we describe the crystal structures of PqqC and its complex with PQQ and determine the stoichiometry of H2O2 formation and O2 uptake during the reaction. The PqqC structure(s) reveals a compact seven-helix bundle that provides the scaffold for a positively charged active site cavity. Product binding induces a large conformational change, which results in the active site recruitment of amino acid side chains proposed to play key roles in the catalytic mechanism. PqqC is unusual in that it transfers redox equivalents to molecular oxygen without the assistance of a redox active metal or cofactor. The structure of the enzyme-product complex shows additional electron density next to R179 and C5 of PQQ, which can be modeled as O2 or H2O2, indicating a site for oxygen binding. We propose a reaction sequence that involves base-catalyzed cyclization and a series of quinone-quinol tautomerizations that are followed by cycles of O2/H2O2-mediated oxidations. << Less
Proc. Natl. Acad. Sci. U.S.A. 101:7913-7918(2004) [PubMed] [EuropePMC]