your a and c axes are very similar; and your beta is near 120°: It sounds me a twinned crystal. Did you perform a twinning analysis in P21 space group? Can you post any refined parametrs (R, Rfree, Resolution, Wilson ADP)?
-----CCP4 bulletin board <[email protected]> ha scritto: -----
Per: [email protected]
Da: wtempel
Inviato da: CCP4 bulletin board
Data: 19/04/2012 07.45PM
Oggetto: [ccp4bb] indexing(?) question in P21
Hello all,
Da: wtempel
Inviato da: CCP4 bulletin board
Data: 19/04/2012 07.45PM
Oggetto: [ccp4bb] indexing(?) question in P21
Hello all,
I am puzzled by this situation:
I have two different crystal of the same protein, in the presence, one in the absence of a ligand.
Both structures refine nicely in space group P21.
Cell constants (a,b,c,beta) are (i) 61,124,61,119 (a<c by a hair) and (ii) 59,125,61,118. There is a SINGLE protein molecule in the ASU. To facilitate future analysis and comparison between both structures, I have tried (incl. reindexing) to refine both structures with as similar as possible translational/rotational states as possible. A failed to do any better than having them offset by approx. 32A exactly along the a-xis. Considering the pseudo-hexagonal cell and the extent of the offset being so close to a/2, c/2 or b/3, I have the feeling that I am missing something. What could it be?
Thank you as always.
Wolfram Tempel
