When this happens, I firstly suspect that the spacegroup may be
wrong. We had a case where the symmetry was pseudo I4212 but was really
I222 (or was it really I212121) Anyway most of the structure obeyed the
I41212 symmetry but there was a tail which did not..)
Feed the unmerged reflections into pointless and see what it suggests
Eleanor
Zhou, Tongqing (NIH/VRC) [E] wrote:
Hi Everyone,
I have some problem in refining a structure. The data goes to 2.4A (with some
30% completeness at 2.15A), the structure was solved by MR with Phaser,
refinement was done with Phenix, but the r and r-free are now staying at 26%
and 32%, even with all possible waters and missing fragments added. Data was
collected at APS at cryo condition. One thing I noticed during HKL2000 data
processing was that the chi^2 were way too high at lower resolutions shells, I
had to adjust the default error model in HKL2000 to get the chi^2 to around 1,
but this adjustment reduced the overall I/sigI ratio a lot (from around 20 to
5).
The quality of electron density maps looks fine to me for a 2.4 A data set and
I was able to build all the missing CDR loops for the antibody in the complex.
I am lost now, should I just re-collect a new data set?
Thanks,
Tongqing
Tongqing Zhou, Ph.D.
Staff Scientist
Structural Biology Section
Vaccine Research Center, NIAID/NIH
Building 40, Room 4607B
40 Convent Drive, MSC3027
Bethesda, MD 20892
(301) 594-8710 (Tel)
(301) 793-0794 (Cell)
(301) 480-2658 (Fax)
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