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
