Hi John,
if I understand the "make_cv_twin.inp" correctly, then this script
takes care about separating reflections related by the twin law to
avoid a potential bias of the Free-R set with twin-law-related
reflections from the working set. At least, in the source of this
script I read the comment: "{- make sure all twin related reflections
are in the same set -}". If this is true, then you simply don't have
to worry any further about your good R-factors, but enjoy a very well
refined structure!
Maybe, the authors of this CNS script could comment on this
separation of reflections?
Best regards,
Dirk.
Am 23.10.2007 um 15:32 schrieb john kryst:
Hi CCP4bb ,
Thanks for your suggestions... here is the summary of
the structure...
I am working in deletion and point mutants. I have a mutant (P61
resoln 3.1A) with partial twinning with twinning fraction 0.28.
Wilson b-factor is 50. The data collected in the home source with
normal exposure time. The rmsd's of the refined structure is
0.0081 (bonds) and 1.38672 (angles). Molprobity is score is 50
without any manual model building (just after the refinement).
Since the structure is twinned new free R-flag has been chosen
according to CNS make_cv_twin.inp. The b-factor has been flattened
to 30. Then rigid-body_twin refinement followed by simulated
annealing_twin is done (heating the structure up to 5000K with
different initial velocity trials). The R and R free after this
step is 18.35 and 27.22. Then i did bgroup_twin refinement which
gave me R and R free 17.06 25.63. Further model building and
refinement tend to reduce the R and Rfee upto 15 and 23.
I deleted some portion of the molecule and did refinement. But
proper density appeared after it.
Please help me out.
John
*******************************************************
Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: [EMAIL PROTECTED]
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