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[[Image:1fev.gif|left|200px]]<br /><applet load="1fev" size="350" color="white" frame="true" align="right" spinBox="true"
caption="1fev, resolution 2.25&Aring;" />
'''CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S'''<br />


==Overview==
==CRYSTAL STRUCTURE OF THE ALA4AIB MUTATION IN RNASE S==
The S protein-S peptide interaction is a model system to study binding thermodynamics in proteins. We substituted alanine at position 4 in S peptide by alpha-aminoisobutyric acid (Aib) to investigate the effect of this substitution on the conformation of free S peptide and on its binding to S protein. The thermodynamic consequences of this replacement were studied using isothermal titration calorimetry. The structures of the free and complexed peptides were studied using circular dichroic spectroscopy and X-ray crystallography, respectively. The alanine4Aib replacement stabilizes the free S peptide helix and does not perturb the tertiary structure of RNase S. Surprisingly, and in contrast to the wild-type S peptide, the DeltaG degrees of binding of peptide to S pro, over the temperature range 5-30 degrees C, is virtually independent of temperature. At 25 degrees C, the DeltaDeltaG degrees, DeltaDeltaH degrees, DeltaDeltaS and DeltaDeltaCp of binding are 0.7 kcal/mol, 2.8 kcal/mol, 6 kcal/mol x K and -60 kcal/mol x K, respectively. The positive value of DeltaDeltaS is probably due to a decrease in the entropy of uncomplexed alanine4Aib relative to the wild-type peptide. The positive value of DeltaDeltaH: degrees is unexpected and is probably due to favorable interactions formed in uncomplexed alanine4Aib. This study addresses the thermodynamic and structural consequences of a replacement of alanine by Aib both in the unfolded and complexed states in proteins.
<StructureSection load='1fev' size='340' side='right'caption='[[1fev]], [[Resolution|resolution]] 2.25&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1fev]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Bos_taurus Bos taurus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FEV OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1FEV 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]] 2.25&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=AIB:ALPHA-AMINOISOBUTYRIC+ACID'>AIB</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=1fev FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1fev OCA], [https://pdbe.org/1fev PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1fev RCSB], [https://www.ebi.ac.uk/pdbsum/1fev PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1fev ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RNAS1_BOVIN RNAS1_BOVIN] Endonuclease that catalyzes the cleavage of RNA on the 3' side of pyrimidine nucleotides. Acts on single stranded and double stranded RNA.<ref>PMID:7479688</ref>
== 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/fe/1fev_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=1fev ConSurf].
<div style="clear:both"></div>


==About this Structure==
==See Also==
1FEV is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=SO4:'>SO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Pancreatic_ribonuclease Pancreatic ribonuclease], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.1.27.5 3.1.27.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1FEV OCA].
*[[Ribonuclease 3D structures|Ribonuclease 3D structures]]
 
== References ==
==Reference==
<references/>
Structural and thermodynamic consequences of introducing alpha-aminoisobutyric acid in the S peptide of ribonuclease S., Ratnaparkhi GS, Awasthi SK, Rani P, Balaram P, Varadarajan R, Protein Eng. 2000 Oct;13(10):697-702. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=11112508 11112508]
__TOC__
</StructureSection>
[[Category: Bos taurus]]
[[Category: Bos taurus]]
[[Category: Pancreatic ribonuclease]]
[[Category: Large Structures]]
[[Category: Protein complex]]
[[Category: Ratnaparkhi GS]]
[[Category: Ratnaparkhi, G S.]]
[[Category: Varadarajan R]]
[[Category: Varadarajan, R.]]
[[Category: SO4]]
[[Category: aib]]
[[Category: alpha aminoisobutyric acid]]
 
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