Hi, I am trying to recapitulate a published crystallisation system. The published crystal form is P212121 approx cell dimensions 80, 80, 120 // 90, 90, 90 with one trimer in the ASU
We did not get any crystals in the published conditions but have found a new condition giving data to a much higher resolution than the published one but there is a problem... New crystal form is F222 with approx cell dimensions 40, 40, 120 // 90, 90, 90 - this cell is too small to fit one monomer let alone one trimer. The prep is remarkably clean and there is a high volume of crystals in the drop so unlikely to be a contaminant. I have tried molrep with individual domains in case there has been degradation during crystallisation but this does not look at all promising. I am wondering, given the almost exact halving of the a/b cell dimensions and almost exact equivalence of the c cell dimension, whether this is a particularly egregious form of twinning where the twin is three 2-fold screw axes to cause an apparent reduction in the unit cell. Is there a way to expand the data from the current 40, 40, 120 // 90, 90, 90 unit cell to the larger 'super-cell' 80, 80, 120 // 90, 90, 90 with four copies of the data to then attempt either molep or just twin refinement with the original published model? Any comments / help appreciated - NB: I can't share the actual data or even the target as they are confidential client data... Thanks, take care, Charlie Nichols ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
