Hi Josiah,
The primitive cell is what is important. The primitive cells for C2
and R32:H are the same as the P1 cell you report:
(using phenix.explore_metric_symmetry)
R32:H Niggli cell: (81.728198520053866, 81.728198520053866,
81.728198520053866, 84.166443879693517, 84.166443879693517,
84.166443879693517)
C2 Niggli cell: (81.5370006, 81.567520633215281,
81.567520633215281, 84.147871626167259, 84.163573178668059,
84.163573178668059)
Twinning, pseudo symmetry etc etc can all be possible, even if
intensity statistics indicate that things are fine.
P
2008/10/2 Josiah Obiero [EMAIL PROTECTED]:
Dear all,
I have set of data (~2.7A). After indexing, HKL2000 suggests a
rhombohedral space group or C centered monoclinic space group. I tried
molecular replacement with R32 ( 109.55 109.55 155.28 90.00 90.00
120.00) and C2 (121.092 109.31581.53790.00097.874
90.000) (both have good merging statistics), but did not get any
solution. I also tried P1 ( 81.55381.52781.52384.202
84.13284.156) but did get any solution ( wt structure is known and
the only difference with the wt structure is that the new structure is
complexed with a smaller protein). I expect that there'll be some
domain movement so searched for individual domains in phaser.
The self rotation function in P1 showed both two fold and three fold
peaks but they were both off the centre. The data does not appear to be
twinned. I am curious to know if it is normal for cell dimensions to
drastically vary from one space group to another. I am running out of
ideas, could I be dealing with a wrong space group or pseudosymetry?
Any suggestions would be appreciated.
Thanks.
Josiah.
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P.H. Zwart
Beamline Scientist
Berkeley Center for Structural Biology
Lawrence Berkeley National Laboratories
1 Cyclotron Road, Berkeley, CA-94703, USA
Cell: 510 289 9246
BCSB: http://bcsb.als.lbl.gov
PHENIX: http://www.phenix-online.org
CCTBX: http://cctbx.sf.net
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