*** For details on how to be removed from this list visit the ***
*** CCP4 home page http://www.ccp4.ac.uk ***
If you have pseudosymmetry, how do you treat the data? Same as twinning?
I have a 2.3 A dataset that indexes as C2221 with one protein in the
asymmetric unit. I am also able to process the data as P21 (or it may
have been P212121, I don't have my notes with me at the moment), but
with a dimer in the asymmetric unit. The dimer symmetry axis is
crystallographic in C2221 but non-crystallographic in the P21 case.
Either way, the data seem to process equally well, but I can't get
the R_free much below 27%. The same protein with another ligand also
produced C2221 under different conditions. I collected a better
dataset (higher I/Sig, more redundancy) at a different source. In
spite of being better data, now I can't get the R_free below 30%. I
tried running the data through a twinning server on the net but <I^2>/
<I>^2 = 2.0 (no perfect merohedral twinning). The ligand density
looks great, so I can't be far off.
for reference the unit cell is approx [77, 96, 50] Angstroms with 90,
90, 90 degrees.
Am I being too picky about the R_free or is there something wrong
here? Any ideas?
Richard Gillilan
MacCHESS
Cornell
On Jun 1, 2006, at 7:49 PM, James Irving wrote:
*** For details on how to be removed from this list visit the ***
*** CCP4 home page http://www.ccp4.ac.uk ***
A (very) long shot might be pseudosymmetry - what were the Rmerge
statistics like? How did they compare with monoclinic? A dimer in a
monoclinic space group with non-crystallographic symmetry that
closely
approximates orthorhombic crystallographic symmetry might exhibit
this
behaviour.
On 01/06/06, Yi Xue <[EMAIL PROTECTED]> wrote:
