1ek4

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=DAO:LAURIC+ACID'>DAO</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1dd8|1dd8]]</div></td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[https://en.wikipedia.org/wiki/Beta-ketoacyl-[acyl-carrier-protein]_synthase_I Beta-ketoacyl-[acyl-carrier-protein] synthase I], with EC number [https://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.3.1.41 2.3.1.41] </span></td></tr>

[[https://www.uniprot.org/uniprot/FABB_ECOLI FABB_ECOLI]] Catalyzes the condensation reaction of fatty acid synthesis by the addition to an acyl acceptor of two carbons from malonyl-ACP. Specific for elongation from C-10 to unsaturated C-16 and C-18 fatty acids.

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== Publication Abstract from PubMed ==

BACKGROUND: beta-ketoacyl-acyl carrier protein synthase (KAS) I is vital for the construction of the unsaturated fatty acid carbon skeletons characterizing E. coli membrane lipids. The new carbon-carbon bonds are created by KAS I in a Claisen condensation performed in a three-step enzymatic reaction. KAS I belongs to the thiolase fold enzymes, of which structures are known for five other enzymes. RESULTS: Structures of the catalytic Cys-Ser KAS I mutant with covalently bound C10 and C12 acyl substrates have been determined to 2.40 and 1.85 A resolution, respectively. The KAS I dimer is not changed by the formation of the complexes but reveals an asymmetric binding of the two substrates bound to the dimer. A detailed model is proposed for the catalysis of KAS I. Of the two histidines required for decarboxylation, one donates a hydrogen bond to the malonyl thioester oxo group, and the other abstracts a proton from the leaving group. CONCLUSIONS: The same mechanism is proposed for KAS II, which also has a Cys-His-His active site triad. Comparison to the active site architectures of other thiolase fold enzymes carrying out a decarboxylation step suggests that chalcone synthase and KAS III with Cys-His-Asn triads use another mechanism in which both the histidine and the asparagine interact with the thioester oxo group. The acyl binding pockets of KAS I and KAS II are so similar that they alone cannot provide the basis for their differences in substrate specificity.

Structures of beta-ketoacyl-acyl carrier protein synthase I complexed with fatty acids elucidate its catalytic machinery.,Olsen JG, Kadziola A, von Wettstein-Knowles P, Siggaard-Andersen M, Larsen S Structure. 2001 Mar 7;9(3):233-43. PMID:11286890<ref>PMID:11286890</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 1ek4" style="background-color:#fffaf0;"></div>

== References ==

<references/>

[[Category: Kadziola, A]]

[[Category: Larsen, S]]

[[Category: Olsen, J G]]

[[Category: Siggaard-Andersen, M]]

[[Category: Wettstein-Knowles, P von]]

[[Category: Transferase]]