Hi Chandan, The answer to your question about buffers is to use any buffer that does not bind to metal ions like zinc for example. I have used TRIS and MES myself successfully for crystallization of zinc finger proteins. What kind of zinc fingers do you have? If there is histidine then you cannot go below pH 5.0 or you will lose the zinc. High pH is not a problem up to pH 10.0 as long as you keep the reducing agent concentration low at say 1 mM. Obviously do not use EDTA or any other metal ion chelators in the prep, or in the crystallization mix.
Have you checked the protein for activity or binding or proteolysis? Cheers. Ray Ray Brown PhD 3DBioScience LLC Url: www.3dbioscience.com
