Re: [ccp4bb] MAD and twinning

2007-04-25 Thread George M. Sheldrick
XPREP may well be the only program that can read a .sca file, detwin it as you suggest, and write another .sca file directly. Since it is a MAD experiment and the true space group is probably P31 or P32, you must be careful to check that the different wavelengths have been indexed consistently.

[ccp4bb] R and Rfree

2007-04-25 Thread U Sam
Hi Everybody, I have small query. I am feeding ions and correcting few residues into my final structure. If R increases and Rfree decreases or vice versa in the subsequent refinement, which one I should accept and go forward. Thanks. Sam ___

[ccp4bb] Torsion of acetyl coenzyme a

2007-04-25 Thread Peng Zhang
Dear friends, Recently, I solved a structure with a ligand acetyl coenzyme a (ACO) at 2.5A, in which I need to modelled the ACO in O. I generated the torsion file with the PRODRG2 server, the torsion file is attached. I wonder why only the 1-12 angles can be torsioned in o(8.0)? Thanks in advance.

Re: [ccp4bb] R and Rfree

2007-04-25 Thread David Briggs
Hi Sam Dogma would state that you are trying to maximise the correlation between your model and the structure, *without over fitting* and Rfree should thus be minimised. However, you are likley using a maximum likelihood target, so you should maximise the likelihood so that the model accurately