Dear CCP4BB:
We have a protein-DNA complex from a twinned crystal (space group
P31). I detwinned the data and refined the structure to 2.1 A with
Rfree=28.8% before adding water and nucleotides. We can only observe
density for two of the 25 nucleotides. I noticed that the B-factors
are very high (around 50-60 A^2). Not many water molecules can be
added using a 80 A^2 cutoff. We determined the structure of the
unbound protein, and the B-factors are almost as high. I tried
fixing the B-factors at 20, but Rfree increased to 30.9%. Is this
indicative of an error that can be fixed? Thank you.
Gregg
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Gregg Crichlow
Dept. of Pharmacology
Yale University
P.O. Box 208066
New Haven, CT 06520-8066
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