View source for 3gct


==STRUCTURE OF GAMMA-*CHYMOTRYPSIN IN THE RANGE $P*H 2.0 TO $P*H 10.5 SUGGESTS THAT GAMMA-CHYMOTRYPSIN IS A COVALENT ACYL-ENZYME ADDUCT AT LOW $P*H==
<StructureSection load='3gct' size='340' side='right'caption='[[3gct]], [[Resolution|resolution]] 1.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[3gct]] is a 4 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=3GCT OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3GCT 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]] 1.6&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><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=3gct FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3gct OCA], [https://pdbe.org/3gct PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3gct RCSB], [https://www.ebi.ac.uk/pdbsum/3gct PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3gct ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/CTRA_BOVIN CTRA_BOVIN] 
== 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/gc/3gct_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=3gct ConSurf].
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== Publication Abstract from PubMed ==
Crystals of gamma-chymotrypsin (gamma-CHT) grown at pH 7.0 are stable from pH 2.0 to 11.0. Crystalline gamma-CHT therefore provides an unusually favourable system to observe the structure of a protein and its bound solvent over a broad range of pH. In this report we describe the high-resolution refined structure of gamma-CHT at pH values of 2.0, 7.0 and 10.5. The apparent tetrapeptide seen bound in the active site of gamma-CHT at pH 7.0 is also present at pH 2.0 and 10.5 although it is better defined at low pH. A comparison of the respective structures shows that there is additional electron density in the low pH structure at the point where the side-chain of Ser 195 approaches most closely to the presumptive inhibitor. This suggests that the adduct is most likely to be covalently linked to the enzyme at low pH and to be non-covalent at higher pH. As the pH is lowered from 7.0 to 2.0, the side-chain of His 40 rotates approximately 120 degrees about its C alpha-C beta bond and, in concert, the side-chain of Gln 34 also rotates approximately 140 degrees about its C alpha-C beta bond. Apart from these localized rearrangements in the vicinity of His 40, the structure of gamma-CHT at pH 2.0 is very similar to that at neutral pH. The structure of gamma-CHT at pH 10.5 is also seen to be almost identical with that at neutral pH. There is no indication that the internal salt bridge between Asp 194 and the alpha-amino group of lle 16 begins to dissociate at pH 10.5. With the exception of the vicinity of His 40, the structure of the bound solvent in the crystal structures at low, neutral and high pH is very similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of gamma-chymotrypsin in the range pH 2.0 to pH 10.5 suggests that gamma-chymotrypsin is a covalent acyl-enzyme adduct at low pH.,Dixon MM, Brennan RG, Matthews BW Int J Biol Macromol. 1991 Apr;13(2):89-96. PMID:1888717<ref>PMID:1888717</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 3gct" style="background-color:#fffaf0;"></div>

==See Also==
*[[Chymotrypsin 3D structures|Chymotrypsin 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Bos taurus]]
[[Category: Large Structures]]
[[Category: Dixon MM]]
[[Category: Matthews BW]]