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[ccp4bb]: RE: Crystal packing



Title:
Thank you all for your thoughtful suggestion.  I think I should have stated the crystal conditions and the experiment we have already done more clearly.  

The protein is shown to be a monomer in solution by rate zonal centrifugation, gel filtration, cross-linking, sedimentation equilibrium and low angle X-ray scattering.  Dynamic light scattering measurements indicated a monodisperse solution with an apparent molecular weight of 79 kDa, which is in reasonable agreement with that for the monomer (63.9 kDa).  The protein is rather long and thin, 146 x 46 x 34 Å.  

Native protein is in 20 mM Tris-HCL, pH 8.5, and 50 mM sodium chloride.  The crystal conditions for these three crystal forms are somewhat similiar.   Form I crystals were crystallized in  30% MPD, 0.1 M sodium acetate at pH 4.6, 20 mM CaCl2.  Form II was in 50% MPD, 0.1 M sodium acetate at pH 5.0, 10 mM CaCl2.  Form III:  63% MPD, 0.19 M sodium acetate at pH 4.53, 10 mM CaCl2, with 0.1-0.2% final concentration of glutaraldehyde.  

I will summarize all the answers as soon as possible.

Lan