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2qx8: Difference between revisions

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== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[2qx8]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QX8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2QX8 FirstGlance]. <br>
<table><tr><td colspan='2'>[[2qx8]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2QX8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2QX8 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=FAD:FLAVIN-ADENINE+DINUCLEOTIDE'>FAD</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=ML2:N-[2-(2-IODO-5-METHOXY-1H-INDOL-3-YL)ETHYL]ACETAMIDE'>ML2</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.6&#8491;</td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1sg0|1sg0]], [[2qx4|2qx4]], [[2qx6|2qx6]], [[2qx9|2qx9]]</div></td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=FAD:FLAVIN-ADENINE+DINUCLEOTIDE'>FAD</scene>, <scene name='pdbligand=GOL:GLYCEROL'>GOL</scene>, <scene name='pdbligand=ML2:N-[2-(2-IODO-5-METHOXY-1H-INDOL-3-YL)ETHYL]ACETAMIDE'>ML2</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">NQO2, NMOR2 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=9606 Homo sapiens])</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Ribosyldihydronicotinamide_dehydrogenase_(quinone) Ribosyldihydronicotinamide dehydrogenase (quinone)], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.10.99.2 1.10.99.2] </span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2qx8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qx8 OCA], [https://pdbe.org/2qx8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2qx8 RCSB], [https://www.ebi.ac.uk/pdbsum/2qx8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2qx8 ProSAT]</span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2qx8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2qx8 OCA], [https://pdbe.org/2qx8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2qx8 RCSB], [https://www.ebi.ac.uk/pdbsum/2qx8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2qx8 ProSAT]</span></td></tr>
</table>
</table>
== Function ==
== Function ==
[[https://www.uniprot.org/uniprot/NQO2_HUMAN NQO2_HUMAN]] The enzyme apparently serves as a quinone reductase in connection with conjugation reactions of hydroquinones involved in detoxification pathways as well as in biosynthetic processes such as the vitamin K-dependent gamma-carboxylation of glutamate residues in prothrombin synthesis.<ref>PMID:18254726</ref>
[https://www.uniprot.org/uniprot/NQO2_HUMAN NQO2_HUMAN] The enzyme apparently serves as a quinone reductase in connection with conjugation reactions of hydroquinones involved in detoxification pathways as well as in biosynthetic processes such as the vitamin K-dependent gamma-carboxylation of glutamate residues in prothrombin synthesis.<ref>PMID:18254726</ref>  
== Evolutionary Conservation ==
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
[[Image:Consurf_key_small.gif|200px|right]]
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2qx8 ConSurf].
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=2qx8 ConSurf].
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== Publication Abstract from PubMed ==
Melatonin exerts its biological effects through at least two transmembrane G-protein-coupled receptors, MT1 and MT2, and a lower-affinity cytosolic binding site, designated MT3. MT3 has recently been identified as QR2 (quinone reductase 2) (EC 1.10.99.2) which is of significance since it links the antioxidant effects of melatonin to a mechanism of action. Initially, QR2 was believed to function analogously to QR1 in protecting cells from highly reactive quinones. However, recent studies indicate that QR2 may actually transform certain quinone substrates into more highly reactive compounds capable of causing cellular damage. Therefore it is hypothesized that inhibition of QR2 in certain cases may lead to protection of cells against these highly reactive species. Since melatonin is known to inhibit QR2 activity, but its binding site and mode of inhibition are not known, we determined the mechanism of inhibition of QR2 by melatonin and a series of melatonin and 5-hydroxytryptamine (serotonin) analogues, and we determined the X-ray structures of melatonin and 2-iodomelatonin in complex with QR2 to between 1.5 and 1.8 A (1 A=0.1 nm) resolution. Finally, the thermodynamic binding constants for melatonin and 2-iodomelatonin were determined by ITC (isothermal titration calorimetry). The kinetic results indicate that melatonin is a competitive inhibitor against N-methyldihydronicotinamide (K(i)=7.2 microM) and uncompetitive against menadione (K(i)=92 microM), and the X-ray structures shows that melatonin binds in multiple orientations within the active sites of the QR2 dimer as opposed to an allosteric site. These results provide new insights into the binding mechanisms of melatonin and analogues to QR2.
Kinetic, thermodynamic and X-ray structural insights into the interaction of melatonin and analogues with quinone reductase 2.,Calamini B, Santarsiero BD, Boutin JA, Mesecar AD Biochem J. 2008 Jul 1;413(1):81-91. PMID:18254726<ref>PMID:18254726</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 2qx8" style="background-color:#fffaf0;"></div>


==See Also==
==See Also==
*[[Quinone reductase|Quinone reductase]]
*[[Quinone reductase 3D structures|Quinone reductase 3D structures]]
== References ==
== References ==
<references/>
<references/>
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[[Category: Homo sapiens]]
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Large Structures]]
[[Category: Boutin, J A]]
[[Category: Boutin JA]]
[[Category: Calamini, B]]
[[Category: Calamini B]]
[[Category: Mesecar, A D]]
[[Category: Mesecar AD]]
[[Category: Santarsiero, B D]]
[[Category: Santarsiero BD]]
[[Category: Fad]]
[[Category: Flavoprotein]]
[[Category: Metal-binding]]
[[Category: Oxidoreductase]]

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