Rfree in molecular replacement
Anja.Rabijns at farm.kuleuven.ac.be
Wed Jul 23 02:26:38 EST 1997
At the moment I am trying to solve the structure of a protein by molecular
replacement. This protein is very similar to the search model I am using
(only the first ten amino acids are missing). Both proteins crystallize in
the C2 spacegroup, however, the cell parameters are slightly different.
The structure of the search model was solved to 1.8 A and for the unknown
structure I only have a 75 % complete data set to 2.6 A.
Now, the problem is that when I try to refine the new structure in X-PLOR
after having found an easy solution for the molecular replacement, I
immediately get a large difference between Rwork and Rfree. Rwork goes to
crazy values of about 14 % and Rfree is around 36 %.
My question is what can be the reason for this and how can I avoid this
Any suggestions are welcome,
Thanks in advance,
Laboratory for Analytical Chemistry and Medicinal Physicochemistry
E. Van Evenstraat 4,
Tel: (+32)-16-32 34 21
Fax: (+32)-16-32 34 14
anja.rabijns at farm.kuleuven.ac.be
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