4aoy: Difference between revisions

<table><tr><td colspan='2'>[[4aoy]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Acetivibrio_thermocellus Acetivibrio thermocellus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4AOY OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4AOY FirstGlance]. <br>

</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.35&#8491;</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=4aoy FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4aoy OCA], [https://pdbe.org/4aoy PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4aoy RCSB], [https://www.ebi.ac.uk/pdbsum/4aoy PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4aoy ProSAT]</span></td></tr>

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Isocitrate dehydrogenase (IDH) catalyzes the oxidative NAD(P)(+)-dependent decarboxylation of isocitrate into alpha-ketoglutarate and CO2 and is present in organisms spanning the biological range of temperature. We have solved two crystal structures of the thermophilic Clostridium thermocellum IDH (CtIDH), a native open apo CtIDH to 2.35 A and a quaternary complex of CtIDH with NADP(+), isocitrate and Mg(2+) to 2.5 A. To compare to these a quaternary complex structure of the psychrophilic Desulfotalea psychrophila IDH (DpIDH) was also resolved to 1.93 A. CtIDH and DpIDH showed similar global thermal stabilities with melting temperatures of 67.9 and 66.9 degrees C, respectively. CtIDH represents a typical thermophilic enzyme, with a large number of ionic interactions and hydrogen bonds per residue combined with stabilization of the N and C termini. CtIDH had a higher activity temperature optimum, and showed greater affinity for the substrates with an active site that was less thermolabile compared to DpIDH. The uncompensated negative surface charge and the enlarged methionine cluster in the hinge region both of which are important for cold activity in DpIDH, were absent in CtIDH. These structural comparisons revealed that prokaryotic IDHs in subfamily II have a unique locking mechanism involving Arg310, Asp251' and Arg255 (CtIDH). These interactions lock the large domain to the small domain and direct NADP(+) into the correct orientation, which together are important for NADP(+) selectivity.

The complex structures of isocitrate dehydrogenase from Clostridium thermocellum and Desulfotalea psychrophila suggest a new active site locking mechanism.,Leiros HK, Fedoy AE, Leiros I, Steen IH FEBS Open Bio. 2012 Jul 7;2:159-72. doi: 10.1016/j.fob.2012.06.003. Print 2012. PMID:23650595<ref>PMID:23650595</ref>

==See Also==

*[[Isocitrate dehydrogenase 3D structures|Isocitrate dehydrogenase 3D structures]]

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</StructureSection>

[[Category: Acetivibrio thermocellus]]

[[Category: Large Structures]]

[[Category: Fedoy A-E]]

[[Category: Leiros H-KS]]

[[Category: Leiros I]]

[[Category: Steen IH]]