View source for 4yas


==HYDROXYNITRILE LYASE COMPLEXED WITH CHLORALHYDRATE==
<StructureSection load='4yas' size='340' side='right'caption='[[4yas]], [[Resolution|resolution]] 2.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4yas]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Hevea_brasiliensis Hevea brasiliensis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4YAS OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4YAS 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&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CLX:TRI-CHLORO-ACETALDEHYDE'>CLX</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=4yas FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4yas OCA], [https://pdbe.org/4yas PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4yas RCSB], [https://www.ebi.ac.uk/pdbsum/4yas PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4yas ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/HNL_HEVBR HNL_HEVBR] Involved in cyanogenesis, the release of HCN from injured tissues. Decomposes a varieties of (R) or (S) cyanohydrins into HCN and the corresponding aldehydes and ketones. The natural substrate of this enzyme is (S)-acetone cyanohydrin.
== 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/ya/4yas_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=4yas ConSurf].
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== Publication Abstract from PubMed ==
The 3D structures of complexes between the hydroxynitrile lyase from Hevea brasiliensis (Hb-HNL) and several substrate and/or inhibitor molecules, including trichloracetaldehyde, hexafluoracetone, acetone, and rhodanide, were determined by X-ray crystallography. The complex with trichloracetaldehyde showed a covalent linkage between the protein and the inhibitor, which had apparently resulted from nucleophilic attack of the catalytic Ser80-Ogamma. All other complexes showed the substrate or inhibitor molecule merely hydrogen bonded to the protein. In addition, the native crystal structure of Hb-HNL was redetermined at cryo-temperature and at room temperature, eliminating previous uncertainties concerning residual electron density within the active site, and leading to the observation of two conserved water molecules. One of them was found to be conserved in all complex structures and appears to have mainly structural significance. The other water molecule is conserved in all structures except for the complex with rhodanide; it is hydrogen bonded to the imidazole of the catalytic His235 and appears to affect the Hb-HNL catalyzed reaction. The observed 3D structural data suggest implications for the enzyme mechanism. It appears that the enzyme-catalyzed cyanohydrin formation is unlikely to proceed via a hemiacetal or hemiketal intermediate covalently attached to the enzyme, despite the observation of such an intermediate for the complex with trichloracetaldehyde. Instead, the data are consistent with a mechanism where the incoming substrate is activated by hydrogen bonding with its carbonyl oxygen to the Ser80 and Thr11 hydroxy groups. A hydrogen cyanide molecule subsequently replaces a water molecule and is deprotonated presumably by the His235 base. Deprotonation is facilitated by the proximity of the positive charge of the Lys236 side chain.

Three-dimensional structures of enzyme-substrate complexes of the hydroxynitrile lyase from Hevea brasiliensis.,Zuegg J, Gruber K, Gugganig M, Wagner UG, Kratky C Protein Sci. 1999 Oct;8(10):1990-2000. PMID:10548044<ref>PMID:10548044</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 4yas" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Hevea brasiliensis]]
[[Category: Large Structures]]
[[Category: Gugganig M]]
[[Category: Kratky C]]
[[Category: Wagner UG]]
[[Category: Zuegg J]]