You dont give the space group or cell or the number of molecules in the
unit cell.
However it is surprising that Arp/Warp didnt complete a solution at this
resolution.
First suspicion always is that there is something wrong with the data.
What do your TRUNCATE plots look like( generated when you Import Data to
mtz)?
Is the Wilson plot OK? Are the moments as expected? Is the data
anisotropic? Could the crystal be twinned?
Second, there may be some ambiguity in the MR solution. Is that
possible? Could the space group be wrong?
And so on..
Eleanor
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Hi, all:
I tried to solve a protein structure by molecular replacement. The apo
form is already solved, I crystallized it with Cu(II). The data diffracted
to 1.6A, the highest resolution shell has more than 80% completeness, R is
43%.
I used phaser to find the MR solutin ,then used Refmac to do rigid body
refinement, and restrained refinement. I adjusted weighing factor to keep
chi^2 exactly 0.01. After these steps, R is around 0.30, Rfree is about
0.37.
Then I fed all the data to arp/warp, it showed that while R decresed,
Rfree increased, and finally, Rfree is around 40%.
I tried to manual build the model, however, I found that most density
were unambigously assigned. I only need to do some small adjustments, these
minor adjustments did not improve R factors a lot.
All suggestions are highly appreciated.
Best regards
Yi
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