Dear Andrew, Just a few questions: -Do the processing/refinement programs suggest twinning? -Are you sure your space group is P21 and not P2? Did you try MR in P2? -How many protein molecules do you expect in the asymmetric unit?
P2(1) is a very low symmetry space group. In this case I would not try to be clever and just reprocess the data in P1 and run MR in P1. With Zanuda you can afterwards try to figure out what the real space group could be. Best, Herman Von: CCP4 bulletin board [mailto:CCP4BB@JISCMAIL.AC.UK] Im Auftrag von Andrew Lovering Gesendet: Montag, 19. Dezember 2016 09:43 An: CCP4BB@JISCMAIL.AC.UK Betreff: [ccp4bb] unusual monoclinic relation? Dear All, I have just collected data on a mutant of a protein that should be facile to solve by molrep (one residue/320 changed, approx 2Ang resolution) but is proving problematic. Data merging stats look good. The spacegroup is monoclinic, P21, the cell: a=39.47 b=157.36 c=74.9 beta=98.26 I spotted the relevant monoclinic twin laws on ccp4 twinning page and all relate multiples of axes a and c with one another (na +nc etc) but in the above case it would appear b~ = 4a There are other datasets, all index in this way, some hint at issues by indexing with the alternate a=74 b=157 c=79 (where a and c "swap" with a doubled, and thus our b=4a turns into b=2c) I would appreciate any advice on how to progress! Be nice to solve it pre-xmas..... Best & thanks in advance, Andy
