2d91: Difference between revisions

[[Image:2d91.gif|left|200px]]<br /><applet load="2d91" size="350" color="white" frame="true" align="right" spinBox="true"  

New techniques are presented for the preparation of iodine derivatives, involving vapour diffusion of iodine. Firstly, in the vaporizing iodine labelling (VIL) technique, a small amount of KI/I(2) solution is enclosed in a crystallization well, with the result that gaseous I(2) molecules diffuse into the crystallization droplets without exerting substantial changes in ionic strength in the target crystals. Once they have diffused into the droplet, the I(2) molecules sometimes iodinate accessible tyrosines at ortho positions. Secondly, when iodination is insufficient, the hydrogen peroxide VIL (HYPER-VIL) technique can be further applied to increase the iodination ratio by the addition of a small droplet of hydrogen peroxide (H(2)O(2)) to the crystallization well; the gaseous H(2)O(2) also diffuses into the crystallization droplet to emphasize the iodination. These techniques are most effective for phase determination when coupled with softer X-rays, such as those from Cu Kalpha or Cr Kalpha radiation. The effectiveness of these techniques was assessed using five different crystals. Four of the crystals were successfully iodinated, providing sufficient phasing power for structure determination.

2D91 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Gallus_gallus Gallus gallus] with <scene name='pdbligand=IOD:'>IOD</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Active as [http://en.wikipedia.org/wiki/Lysozyme Lysozyme], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.17 3.2.1.17] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2D91 OCA].  

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