5acn: Difference between revisions

[[Image:5acn.gif|left|200px]]<br /><applet load="5acn" size="350" color="white" frame="true" align="right" spinBox="true"  

The structure of activated pig heart aconitase [citrate(isocitrate) hydro-lyase, EC 4.2.1.3] containing a [4Fe-4S] cluster has been refined at 2.5-A resolution to a crystallographic residual of 18.2%. Comparison of this structure to the recently determined 2.1-A resolution structure of the inactive enzyme containing a [3Fe-4S] cluster, by difference Fourier analysis, shows that upon activation iron is inserted into the structure isomorphously. The common atoms of the [3Fe-4S] and [4Fe-4S] cores agree within 0.1 A; the three common cysteinyl S gamma ligand atoms agree within 0.25 A. The fourth ligand of the Fe inserted into the [3Fe-4S] cluster is a water or hydroxyl from solvent, consistent with the absence of a free cysteine ligand in the enzyme active site cleft and the isomorphism of the two structures. A water molecule occupies a similar site in the crystal structure of the inactive enzyme.

5ACN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sus_scrofa Sus scrofa] with <scene name='pdbligand=SO4:'>SO4</scene>, <scene name='pdbligand=F3S:'>F3S</scene> and <scene name='pdbligand=TRC:'>TRC</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Aconitate_hydratase Aconitate hydratase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.2.1.3 4.2.1.3] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5ACN OCA].  

[[Category: Robbins, A H.]]

[[Category: Stout, C D.]]

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