4lxi

<StructureSection load='4lxi' size='340' side='right' caption='[[4lxi]], [[Resolution|resolution]] 2.17&Aring;' scene=''>

<table><tr><td colspan='2'>[[4lxi]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Sphww Sphww]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4LXI OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=4LXI FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=22J:(3E,5R)-5-FLUORO-6-(2-FLUOROPHENYL)-2,6-DIOXOHEX-3-ENOIC+ACID'>22J</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[4lxg|4lxg]], [[4lxh|4lxh]]</td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">dxnB2, Swit_3055 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=392499 SPHWW])</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/2,6-dioxo-6-phenylhexa-3-enoate_hydrolase 2,6-dioxo-6-phenylhexa-3-enoate hydrolase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.7.1.8 3.7.1.8] </span></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=4lxi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4lxi OCA], [http://pdbe.org/4lxi PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=4lxi RCSB], [http://www.ebi.ac.uk/pdbsum/4lxi PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=4lxi ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

The meta-cleavage product (MCP) hydrolases utilize a Ser-His-Asp triad to hydrolyze a carbon-carbon bond. Hydrolysis of the MCP substrate has been proposed to proceed via an enol-to-keto tautomerization followed by a nucleophilic mechanism of catalysis. Ketonization involves an intermediate, ESred, possessing a remarkable bathochromically-shifted absorption spectrum. We investigated the catalytic mechanism of the MCP hydrolases using DxnB2 from Sphingomonas wittichii RW1. Pre-steady-state kinetic and LC ESI/MS evaluation of the DxnB2-mediated hydrolysis of 2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoic acid (HOPDA) to 2-hydroxy-2,4-pentadienoic acid (HPD) and benzoate support a nucleophilic mechanism catalysis. In DxnB2, the rate of ESred decay and product formation showed a solvent kinetic isotope effect of 2.5 indicating that a proton transfer reaction, assigned here to substrate ketonization, limits the rate of acylation. For a series of substituted MCPs, this rate was linearly dependent on MCP pKa2 (betanuc ~1). Structural characterization of DxnB2 S105A:MCP complexes revealed that the catalytic histidine is displaced upon substrate-binding. The results provide evidence for enzyme-catalyzed ketonization in which the catalytic His-Asp pair does not play an essential role. The data further suggest that ESred represents a dianionic intermediate that acts as a general base to activate the serine nucleophile. This substrate-assisted mechanism of nucleophilic catalysis distinguishes MCP hydrolases from other serine hydrolases.

A substrate-assisted mechanism of nucleophile activation in a Ser-His-Asp containing C-C bond hydrolase.,Ruzzini AC, Bhowmik S, Ghosh S, Yam KC, Bolin JT, Eltis LD Biochemistry. 2013 Sep 25. PMID:24067021<ref>PMID:24067021</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 4lxi" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: 2,6-dioxo-6-phenylhexa-3-enoate hydrolase]]

[[Category: Sphww]]

[[Category: Bhowmik, S]]

[[Category: Bolin, J T]]

[[Category: Rossmann fold]]