*** For details on how to be removed from this list visit the *** *** CCP4 home page http://www.ccp4.ac.uk ***
Hi there! I have a problem during refinement of apparently good data... the protein crystallised in space group P21 with following cell parameters: 44.5 86.5 44.6 90 112.5 90 the crystal diffracted up to 1.5 A and the diffraction pattern looked very good some statistics from the CORRECT.LP: Res. Range I/sigma(I) Chi² R obs R exp refl. accepted rej. 43.162 1.498 8.56 1.00 4.91 5.35 139902 138325 750 after Molrep, rigid body and restrained refinement with ccp4, the R factor is still around 40 % and won't go further down, and there are some regions where the density looks really bad... I read that twinning could be an explanation so i checked <I²>/<I>² which ranges from 1.75 to 2 depending on the resolution, which means that the crystal is twinned. As far as I understood is it possible to detwin the data if you know the symmetry between and the relative fractions of the twin domains, but I only found possible twin laws for higher symmetry crystals. Has anyone a clue or some reference how to proceed with this data (which looked so fine in the beginning...)? thanks in advance, David -- Echte DSL-Flatrate dauerhaft für 0,- Euro*! "Feel free" mit GMX DSL! http://www.gmx.net/de/go/dsl
