Hi Rajesh, it can be a bit all over the place: For quick soaks, we typically use 500mM-1000mM. A good starting point might be to simply replace the NaCl concentration in your protein buffer. By some serendipity we also managed to solve a structure by I/S SAD after a 1mM NaI soak. One iodide had found its way into a nice binding pocket. For co-crystallization, mostly 200mM should be fine. Another approach could be to supplement your cryo buffer with iodide, replacing NaCl. NaI is highly soluble in ethylene glycol.
Also see here: http://www.ncbi.nlm.nih.gov/pubmed/21359836 Good luck! Cheers, Jan -- Jan Abendroth Emerald Bio Seattle / Bainbridge Island WA, USA home: Jan.Abendroth_at_gmail.com work: JAbendroth_at_embios.com http://www.emeraldbiostructures.com On May 3, 2012, at 6:51 AM, Rajesh Kumar wrote: > Dear All, > > I have very thin crystals but diffracting. I was not able to handle them > easily for iodide soak. I always lost the crystals during manipulation and > other big crystals obtained after seeding doesn't even give any diffraction. > I tried for co-crystallizing with NaI. The crystals appear only up to 20 mM > in 1:2 (3ul drop of 1 ul protein and 2ul reservoir). > Is this concentration of iodide is enough for SAD data ( if it had good > incorporation) ? > I appreciate your help. > > Thanks > Rajesh
