View source for 3zhc


==Structure of the phytase from Citrobacter braakii at 2.3 angstrom resolution.==
<StructureSection load='3zhc' size='340' side='right'caption='[[3zhc]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3zhc]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Citrobacter_braakii Citrobacter braakii]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3ZHC OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3ZHC 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]] 2.3&#8491;</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=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=3zhc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3zhc OCA], [https://pdbe.org/3zhc PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3zhc RCSB], [https://www.ebi.ac.uk/pdbsum/3zhc PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3zhc ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/Q2VY22_CITBR Q2VY22_CITBR] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The impact of disulfide bonds on protein stability goes beyond simple equilibrium thermodynamics effects associated with the conformational entropy of the unfolded state. Indeed, disulfide crosslinks may play a role in the prevention of dysfunctional association and strongly affect the rates of irreversible enzyme inactivation, highly relevant in biotechnological applications. While these kinetic-stability effects remain poorly understood, by analogy with proposed mechanisms for processes of protein aggregation and fibrillogenesis, we propose that they may be determined by the properties of sparsely-populated, partially-unfolded intermediates. Here we report the successful design, on the basis of high temperature molecular-dynamics simulations, of six thermodynamically and kinetically stabilized variants of phytase from Citrobacter braakii (a biotechnologically important enzyme) with one, two or three engineered disulfides. Activity measurements and 3D crystal structure determination demonstrate that the engineered crosslinks do not cause dramatic alterations in the native structure. The inactivation kinetics for all the variants displays a strongly non-Arrhenius temperature dependence, with the time-scale for the irreversible denaturation process reaching a minimum at a given temperature within the range of the denaturation transition. We show this striking feature to be a signature of a key role played by a partially unfolded, intermediate state/ensemble. Energetic and mutational analyses confirm that the intermediate is highly unfolded (akin to a proposed critical intermediate in the misfolding of the prion protein), a result that explains the observed kinetic stabilization. Our results provide a rationale for the kinetic-stability consequences of disulfide-crosslink engineering and an experimental methodology to arrive at energetic/structural descriptions of the sparsely populated and elusive intermediates that play key roles in irreversible protein denaturation.

Mechanism of protein kinetic stabilization by engineered disulfide crosslinks.,Sanchez-Romero I, Ariza A, Wilson KS, Skjot M, Vind J, De Maria L, Skov LK, Sanchez-Ruiz JM PLoS One. 2013 Jul 30;8(7):e70013. doi: 10.1371/journal.pone.0070013. Print 2013. PMID:23936134<ref>PMID:23936134</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 3zhc" style="background-color:#fffaf0;"></div>

==See Also==
*[[Phytase 3D structures|Phytase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Citrobacter braakii]]
[[Category: Large Structures]]
[[Category: Ariza A]]
[[Category: DeMaria L]]
[[Category: Sanchez-Romero I]]
[[Category: Sanchez-Ruiz JM]]
[[Category: Skjot M]]
[[Category: Skov LK]]
[[Category: Vind J]]
[[Category: Wilson KS]]