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: (81.537000000000006, 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 (121.092 109.315 81.537 90.000 97.874 > 90.000) (both have good merging statistics), but did not get any > solution. I also tried P1 ( 81.553 81.527 81.523 84.202 > 84.132 84.156) 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. > -- ----------------------------------------------------------------- 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 -----------------------------------------------------------------
