Hi ccp4ers,
I am currently trying to process a crystallographic data set from a
20kDa dumbbell shaped protein which was collected on a Bruker Proteum
series detector. The crystal was badly twinned so the Bruker program
CELL_NOW was used to find twin domains within the data. While it
seperated the data into ~25 different domains it was found that ~ half
of the reflections belonged to one domain. Visual inspection of the
spot prediction for the unit cell in this major domain looked good;
most of the predicted spots were present with good alignment even
though there was quite a few additional spots from other domains. This
major domain was indexed and integrated on its own (without the other
domains) using the Proteum 2/Saint software that supports the
detector. Unscaled, unmerged reflections were then imported into ccp4
using combat and run through scala and ctruncate to scale. merge and
convert to SFs. However when I then fed this output into phaser the
program failed at the anisotropy correction module stating,
"FATAL RUNTIME ERROR: Reflections are not a unique set by symmetry"
Does this suggest I still have issues with twinning/scaling or is it
that Ive got the space group wrong (currently thought to be P212121)?
What specifically are the likely causes of this error message in Phaser?
Thanks in advance for your advice,
John Chipperfield
