unrefineable structure ?

Michael Glazer glazer at physics.oxford.ac.uk
Wed Apr 30 06:30:38 EST 1997


On 30 Apr 1997 schiweck at argon.biophys.mpg.de wrote:

> Dear all,
> 
> I am stuck with the problem of an "unrefineable" antibody (Fab fragment)
> structure. The situation is as follows.
> 
> I have collected data to 3 Angstroems from several crystals. All data can 
> easily processed with DENZO and give consistent results (primitive tetrago-
> nal spacegroup with dimensions of about 78, 78 and 143 Angstroems). In SCALE-
> PACK processing with Laue symmetry P41212 gives a Rmerge (about 6.9 %) which
> is only slightly higher than the one I get for Laue symmetry P41 (6.5 %).
> Pseudo-precession images from the data processed in P41 also indicate that the
> higher symmetric laue group is present. Assuming that either P41212 or the
> enantiomorphic spacegroup P43212 is correct, one gets a Matthews coefficent of 

I would suggest that you could make a quick check as tt whether the 
crystal system is correct by looking at the crystal between crossed 
polars in a microscope down the c-axis. If it is tetragonal the crystal 
will remain dark while it is rotated. If not, then it cannot be 
tetragonal. 

Mike Glazer
Oxford





More information about the Xtal-log mailing list