Re: [ccp4bb] Twinning in C2 ?

2007-07-18 Thread Demetres D. Leonidas
Dear Eleanor, many thanks for all your help and suggestions. We finally have solved the mutant structure. The trick was to use the pseudo translation (there was not any 2 fold axis in the self rotation) with MOLREP which found two molecules and then applied the pseudo translation to provide

Re: [ccp4bb] Twinning in C2 ?

2007-07-13 Thread Demetres D. Leonidas
Dear Eleanor, Yes the native is a dimer and we did the search using the dimer as a model but we had similar results (i.e. all programs find one molecule). The graphs from TRUNCATE show rather normal and I am attaching a gif file with the plot for the cumulative intensity. As for

Re: [ccp4bb] Twinning in C2 ?

2007-07-13 Thread Eleanor Dodson
You dont say whether the molecules in the native cell form a dimer - if so I would search with that (you may need to turn off the packing search) Or whether there is a pseudo translation vector in the mutant form.. Or what the data analysis graphs from TRUNCATE show - are they normal? Eleanor

Re: [ccp4bb] Twinning in C2 ?

2007-07-13 Thread Peter Zwart
Hi Demetres, not sure if this is going to be usefull, but here I go. Your native has a twin law that and your cell is pseudo C222. The mutant is not. pseudo merohedral twinning is not handled well by the twin server you derscribe as it relies on lookup tables. There is no obvious 'perfect'

Re: [ccp4bb] Twinning in C2 ?

2007-07-13 Thread Eleanor Dodson
Oh dear - this is tricky! You could have a dimer in the asymmetric unit, or two monomers in the asymm unit which generate dimers using the crystallographic 2 folds. Things worth checking - What does the self rotation show? Is there a clear 2 fold axis which is different from the