View source for 2ca4


==Sulfite dehydrogenase from Starkeya Novella mutant==
<StructureSection load='2ca4' size='340' side='right'caption='[[2ca4]], [[Resolution|resolution]] 2.10&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2ca4]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Starkeya_novella Starkeya novella]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2CA4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2CA4 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]] 2.1&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HEC:HEME+C'>HEC</scene>, <scene name='pdbligand=MSS:(MOLYBDOPTERIN-S,S)-OXO-MOLYBDENUM'>MSS</scene></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=2ca4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ca4 OCA], [https://pdbe.org/2ca4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ca4 RCSB], [https://www.ebi.ac.uk/pdbsum/2ca4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ca4 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q9LA16_ANCNO Q9LA16_ANCNO] 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/ca/2ca4_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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=2ca4 ConSurf].
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== Publication Abstract from PubMed ==
Sulfite dehydrogenases (SDHs) catalyze the oxidation and detoxification of sulfite to sulfate, a reaction critical to all forms of life. Sulfite-oxidizing enzymes contain three conserved active site amino acids (Arg-55, His-57, and Tyr-236) that are crucial for catalytic competency. Here we have studied the kinetic and structural effects of two novel and one previously reported substitution (R55M, H57A, Y236F) in these residues on SDH catalysis. Both Arg-55 and His-57 were found to have key roles in substrate binding. An R55M substitution increased Km(sulfite)(app) by 2-3 orders of magnitude, whereas His-57 was required for maintaining a high substrate affinity at low pH when the imidazole ring is fully protonated. This effect may be mediated by interactions of His-57 with Arg-55 that stabilize the position of the Arg-55 side chain or, alternatively, may reflect changes in the protonation state of sulfite. Unlike what is seen for SDHWT and SDHY236F, the catalytic turnover rates of SDH R55M and SDHH57A are relatively insensitive to pH (approximately 60 and 200 s(-1), respectively). On the structural level, striking kinetic effects appeared to correlate with disorder (in SDHH57A and SDHY236F) or absence of Arg-55 (SDHR55M), suggesting that Arg-55 and the hydrogen bonding interactions it engages in are crucial for substrate binding and catalysis. The structure of SDHR55M has sulfate bound at the active site, a fact that coincides with a significant increase in the inhibitory effect of sulfate in SDHR55M. Thus, Arg-55 also appears to be involved in enabling discrimination between the substrate and product in SDH.

Molecular basis for enzymatic sulfite oxidation: how three conserved active site residues shape enzyme activity.,Bailey S, Rapson T, Johnson-Winters K, Astashkin AV, Enemark JH, Kappler U J Biol Chem. 2009 Jan 23;284(4):2053-63. Epub 2008 Nov 12. PMID:19004819<ref>PMID:19004819</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 2ca4" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Starkeya novella]]
[[Category: Bailey S]]
[[Category: Kappler U]]