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| ==HALOALKANE DEHALOGENASE MUTANT WITH PHE 172 REPLACED WITH TRP== | | ==HALOALKANE DEHALOGENASE MUTANT WITH PHE 172 REPLACED WITH TRP== |
| <StructureSection load='1hde' size='340' side='right' caption='[[1hde]], [[Resolution|resolution]] 2.70Å' scene=''> | | <StructureSection load='1hde' size='340' side='right'caption='[[1hde]], [[Resolution|resolution]] 2.70Å' scene=''> |
| == Structural highlights == | | == Structural highlights == |
| <table><tr><td colspan='2'>[[1hde]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"corynebacterium_autotrophicum"_baumgarten_et_al._1974 "corynebacterium autotrophicum" baumgarten et al. 1974]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HDE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1HDE FirstGlance]. <br> | | <table><tr><td colspan='2'>[[1hde]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Xanthobacter_autotrophicus Xanthobacter autotrophicus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1HDE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1HDE FirstGlance]. <br> |
| </td></tr><tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/Haloalkane_dehalogenase Haloalkane dehalogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.8.1.5 3.8.1.5] </span></td></tr> | | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.7Å</td></tr> |
| <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1hde FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1hde OCA], [http://pdbe.org/1hde PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1hde RCSB], [http://www.ebi.ac.uk/pdbsum/1hde PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1hde ProSAT]</span></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=1hde FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1hde OCA], [https://pdbe.org/1hde PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1hde RCSB], [https://www.ebi.ac.uk/pdbsum/1hde PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1hde ProSAT]</span></td></tr> |
| </table> | | </table> |
| == Function == | | == Function == |
| [[http://www.uniprot.org/uniprot/DHLA_XANAU DHLA_XANAU]] Catalyzes hydrolytic cleavage of carbon-halogen bonds in halogenated aliphatic compounds, leading to the formation of the corresponding primary alcohols, halide ions and protons. Has a broad substrate specificity, which includes terminally mono- and di- chlorinated and brominated alkanes (up to C4 only). The highest activity was found with 1,2-dichloroethane, 1,3-dichloropropane, and 1,2-dibromoethane. | | [https://www.uniprot.org/uniprot/DHLA_XANAU DHLA_XANAU] Catalyzes hydrolytic cleavage of carbon-halogen bonds in halogenated aliphatic compounds, leading to the formation of the corresponding primary alcohols, halide ions and protons. Has a broad substrate specificity, which includes terminally mono- and di- chlorinated and brominated alkanes (up to C4 only). The highest activity was found with 1,2-dichloroethane, 1,3-dichloropropane, and 1,2-dibromoethane. |
| == Evolutionary Conservation == | | == Evolutionary Conservation == |
| [[Image:Consurf_key_small.gif|200px|right]] | | [[Image:Consurf_key_small.gif|200px|right]] |
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| </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=1hde ConSurf]. | | </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=1hde ConSurf]. |
| <div style="clear:both"></div> | | <div style="clear:both"></div> |
| <div style="background-color:#fffaf0;">
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| == Publication Abstract from PubMed ==
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| Conversion of halogenated aliphatics by haloalkane dehalogenase proceeds via the formation of a covalent alkyl-enzyme intermediate which is subsequently hydrolyzed by water. In the wild type enzyme, the slowest step for both 1,2-dichloroethane and 1,2-dibromoethane conversion is a unimolecular enzyme isomerization preceding rapid halide dissociation. Phenylalanine 172 is located in a helix-loop-helix structure that covers the active site cavity of the enzyme, interacts with the C1 beta of 1,2-dichloroethane during catalysis, and could be involved in stabilization of this helix-loop-helix region of the cap domain of the enzyme. To obtain more information about the role of this residue in dehalogenase function, we performed a mutational analysis of position 172 and studied the kinetics and X-ray structure of the Phe172Trp enzyme. The Phe172Trp mutant had a 10-fold higher Kcat/Km for 1-chlorohexane and a 2-fold higher Kcat for 1,2-dibromoethane than the wild-type enzyme. The X-ray structure of the Phe172Trp enzyme showed a local conformational change in the helix-loop-helix region that covers the active site. This could explain the elevated activity for 1-chlorohexane of the Phe172Trp enzyme, since it allows this large substrate to bind more easily in the active site cavity. Pre-steady-state kinetic analysis showed that the increase in Kcat found for 1,2-dibromoethane conversion could be attributed to an increase in the rate of an enzyme isomerization step that preceeds halide release. The observed conformational difference between the helix-loop-helix structures of the wild-type enzyme and the faster mutant suggests that the isomerization required for halide release could be a conformational change that takes place in this region of the cap domain of the dehalogenase. It is proposed that Phe172 is involved in stabilization of the helix-loop-helix structure that covers the active site of the enzyme and creates a rigid hydrophobic cavity for small apolar halogenated alkanes.
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| Kinetic characterization and X-ray structure of a mutant of haloalkane dehalogenase with higher catalytic activity and modified substrate range.,Schanstra JP, Ridder IS, Heimeriks GJ, Rink R, Poelarends GJ, Kalk KH, Dijkstra BW, Janssen DB Biochemistry. 1996 Oct 8;35(40):13186-95. PMID:8855957<ref>PMID:8855957</ref>
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| From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
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| </div>
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| <div class="pdbe-citations 1hde" style="background-color:#fffaf0;"></div>
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| ==See Also== | | ==See Also== |
| *[[Dehalogenase|Dehalogenase]] | | *[[Dehalogenase 3D structures|Dehalogenase 3D structures]] |
| == References ==
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| <references/>
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| __TOC__ | | __TOC__ |
| </StructureSection> | | </StructureSection> |
| [[Category: Corynebacterium autotrophicum baumgarten et al. 1974]] | | [[Category: Large Structures]] |
| [[Category: Haloalkane dehalogenase]] | | [[Category: Xanthobacter autotrophicus]] |
| [[Category: Dijkstra, B W]] | | [[Category: Dijkstra BW]] |
| [[Category: Kalk, K H]] | | [[Category: Kalk KH]] |
| [[Category: Ridder, I S]] | | [[Category: Ridder IS]] |
| [[Category: Dehalogenase]]
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| [[Category: Detoxification]]
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| [[Category: Hydrolase]]
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