Have you tried microseeding or macroseeding? The original crystals for my Ph D project only diffracted to ~8 angstroms. Microseeding gave crystals that eventually diffracted to ~2.0.
Here are two refs that might be useful: Bergfors, T. (2003). "Seeds to crystals." J Struct Biol 142(1): 66-76. Luft, J. R. and G. T. DeTitta (1999). "A method to produce microseed stock for use in the crystallization of biological macromolecules." Acta Crystallogr D Biol Crystallogr 55(Pt 5): 988-93. On Wed, Sep 9, 2009 at 11:36 AM, Narayanan Ramasubbu<ramas...@umdnj.edu> wrote: > Dear All: > We have been struggling to improve the crystals shown in the attachment. > These crystals form from a protein solution 8 mg/mL (before drop), drop > sizes are 2 microL of protein + 2 microL of well solution (0.1 MES buffer, > pH 6.5, 1.8 M Ammonium sulfate with 12 mM CoCl2). > > The protein was dissolved initially in 20 mM Tris.HCl, pH 8.0 containing 1 > mM EDTA. > > Low cobalt also gives smaller crystals. These diffract up to 8 A. > > Any suggestions to improve these crystals would be most welcome. > > Subbu > > PS: We have used many additives (Hampton Research - including detergent > additives) to alter the morphology but with little success. > -- Jim Fairman Postdoctoral Research Assistant Case Western Reserve University 216-368-3337 jxf...@case.edu
