Wolfram,
Did you solve these structures independently by molecular replacement ?
It sounds like your two solutions might be related by alternative
origins (0,1/2 along a,c). If you translate the second example along
the a axis by -a/2 does it refine with similar R-factors ?
Phil Jeffrey
Princeton
On 4/19/12 1:35 PM, wtempel wrote:
> Hello all,
> I am puzzled by this situation:
> I have two different crystal of the same protein, in the presence, one
> in the absence of a ligand.
> Both structures refine nicely in space group P21.
> Cell constants (a,b,c,beta) are (i) 61,124,61,119 (a<c by a hair) and
> (ii) 59,125,61,118. There is a SINGLE protein molecule in the ASU. To
> facilitate future analysis and comparison between both structures, I
> have tried (incl. reindexing) to refine both structures with as similar
> as possible translational/rotational states as possible. A failed to do
> any better than having them offset by approx. 32A exactly along the
> a-xis. Considering the pseudo-hexagonal cell and the extent of the
> offset being so close to a/2, c/2 or b/3, I have the feeling that I am
> missing something. What could it be?
> Thank you as always.
> Wolfram Tempel
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