Hi Subbu,
You got crystals at 1mg/ml so you probably don't need to concentrate your protein any higher, especially since you suggest that concentrating beyond that is problematic. Instead, you may want to try to optimize the crystallization condition you have already identified. Some possible things to try: additive screen, include specific ligands, different temperature, different ratios of protein solution to crystallization solution, seeding, different crystallization methods (hanging vs. sitting drop, batch, diffusion,...), ...
good luck,
Eric
================================
Eric T. Larson, PhD
Biomolecular Structure Center
Department of Biochemistry
Box 357742
University of Washington
Seattle, WA 98195
email: [log in to unmask]
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On Thu, 21 Jul 2011, Narayanan Ramasubbu wrote:
> Dear All:
> We have been trying to crystallize a protein which is large - > 100 kDa. This
> is soluble but the best we can get is about 1 mg/mL.
> It did crystallize but did not diffract well. Efforts to increase the
> concentration has been unsuccessful. I am wondering whether there are methods
> that others use to increase the concentration other that using amicon columns.
> Any help will be appreciated.
> Thanks
> Subbu
>
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