Dear all,
I am refining a twinned (twinning fraction = 0.213 from Yeates' method)
data using CNS. I refined in two ways.
1. Firstly, I created the .cv file using make_cv_twin.inp from CNS and
then e.g. used minimize_twin.inp for minimization. The Rwork and Rfree
were 19.55% and 22.06% respectively.
2. In the second case, I detwinned the .cv file (.cv file created in the
first case) using detwin_partial.inp from CNS. And then e.g. used
minimize.inp for minimization (Here, I am refining as there is no
twinning). The Rwork and Rfree were 24.5% and 26.59% respectively.
In both cases, I used the same model and without any water. The
resolution of the data is 2.0 Angs, space group R3, twinning operator
(h,-h-k,-l)
By seeing the Rwork and Rfree, I can guess that first case is better. I
also superimposed two minimized pdb's and RMSD = 0.123 Angs.
Now My question is which of the above two ways is the right way to refine
the model. And why there is almost 5% difference in R-factor values.
Any suggestions or references will be highly appreciated.
Thanking you all in advance.
--
Yours Sincerely,
Shankar Prasad Kanaujia
IISc, Bangalore - 12
Mobile: 9845631581
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