1clk: Difference between revisions

[[Image:1clk.gif|left|200px]]<br /><applet load="1clk" size="350" color="white" frame="true" align="right" spinBox="true"  

The structure of xylose isomerase (XyI) from Streptomyces diastaticus No. 7 strain M1033 (SDXyI) has been refined at 1.85 A resolution to conventional and free R factors of 0.166 and 0.219, respectively. SDXyI was crystallized in space group P2(1)2(1)2, with unit-cell parameters a = 87.976, b = 98.836, c = 93.927 A. One dimer of the tetrametric molecule is found in each asymmetric unit. Each monomer consists of two domains: a large N-terminal domain (residues 1-320), containing a parallel eight-stranded alpha/beta barrel, and a small C-terminal loop (residues 321-387), containing five helices linked by random coil. The four monomers are essentially identical in the tetramer, possessing non-crystallographic 222 symmetry with one twofold axis essentially coincident with the crystallographic twofold axis in the space group P2(1)2(1)2, which may explain why the diffraction pattern has strong pseudo-I222 symmetry even at medium resolution. The crystal structures of XyIs from different bacterial strains, especially from Streptomyces, are similar. The alpha2 helix of the alpha/beta barrel has a different position in the structures of different XyIs. The conformation of C-terminal fragment 357-364 in the SDXyI structure has a small number of differences to that of other XyIs. Two Co(2+) ions rather than Mg(2+) ions exist in the active site of the SDXyI structure; SDXyI seems to prefer to bind Co(2+) ions rather than Mg(2+) ions.

1CLK is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Streptomyces_diastaticus Streptomyces diastaticus] with <scene name='pdbligand=MG:'>MG</scene> and <scene name='pdbligand=CO:'>CO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Xylose_isomerase Xylose isomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.3.1.5 5.3.1.5] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1CLK OCA].  

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