View source for 2ofa


==Crystal structure of apo AVR4 (R112L,C122S)==
<StructureSection load='2ofa' size='340' side='right'caption='[[2ofa]], [[Resolution|resolution]] 1.50&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2ofa]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2OFA OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2OFA 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]] 1.5&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=FMT:FORMIC+ACID'>FMT</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=2ofa FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2ofa OCA], [https://pdbe.org/2ofa PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2ofa RCSB], [https://www.ebi.ac.uk/pdbsum/2ofa PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2ofa ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/AVR4_CHICK AVR4_CHICK] 
== 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/of/2ofa_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=2ofa ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The homotetrameric and biotin-binding properties of avidin and streptavidin have been exploited for a myriad of biotechnological applications and theoretical studies. Among the few differences between the two proteins is the capacity of avidin to hydrolyze biotinyl p-nitrophenyl ester (BNP), as opposed to streptavidin, which fully protects the same pseudosubstrate from hydrolysis. Combined mutagenesis and X-ray analysis have been used to attempt to understand this diametric difference in activities. It was found that a charged residue and one of the loops (L3,4) are together responsible for this difference. Recently, the avidin-related analogue AVR4 was found to have an even more pronounced BNP-hydrolysis activity than avidin. Again, the combination of charged residue(s) (Asp39 and/or Arg112) and the rigid conformation of the L3,4 loop was suggested to be responsible for the observed hydrolysis reaction. However, replacement of the latter charged residues in AVR4 resulted in only a modest reduction in hydrolytic activity at most, whereas replacement of the L3,4 loop of avidin with the rigid loop of AVR4 caused a dramatic increase in the activity of avidin. These results clearly demonstrate that the main feature responsible for the observed differences in rates of hydrolysis among the avidins is the conformational status of the L3,4 loop, which imposes conformational constraints on the pseudosubstrate, thereby rendering it susceptible to nucleophilic attack by solvent. In this context, the hydrolytic properties of the avidins reflect enzyme catalysis, in that subtleties in substrate binding are the determining features of catalytic efficiency.

Critical importance of loop conformation to avidin-enhanced hydrolysis of an active biotin ester.,Hayouka R, Eisenberg-Domovich Y, Hytonen VP, Maatta JA, Nordlund HR, Kulomaa MS, Wilchek M, Bayer EA, Livnah O Acta Crystallogr D Biol Crystallogr. 2008 Mar;64(Pt 3):302-8. Epub 2008, Feb 20. PMID:18323625<ref>PMID:18323625</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 2ofa" style="background-color:#fffaf0;"></div>

==See Also==
*[[Avidin 3D structures|Avidin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Gallus gallus]]
[[Category: Large Structures]]
[[Category: Eisenberg-Domovich Y]]
[[Category: Hayouka R]]
[[Category: Livnah O]]