That translation is interesting - R3 indexed as hexagonal has a
crystallographic translation of 0.667 0.333 0.333, so this one
indicated by SFCHECK is related.
The twinning is not very severe so it should refine OK from the PHASER
solution.
Is that so?
Eleanor
On 04/08/2011 05:50 AM, ka...@ssl.serc.iisc.ernet.in wrote:
Respected Madam,
Yes - that is true.
Any crystal might be split, and give diffraction with overlapping
lattices- ie show non-merohedral twinning. If you are lucky/careful you
might only get a few spots which overlap after integration of one of
the>lattices- not enough to be detected as "twinning" from the
statistical>analysis...
but the SG R3 is a classic one for merohedral twinning with operator k,h,-l
Have you looked at the scala log file - you need to check the L test for
twinning, whether there is non-crystallographic translation etc.. as
well>as looking at the moment plots.
I have checked for twinning in L test and H-test both of which indicated
slight twinning. I am attached H-test and L-test graph herewith.
Sfcheck also indicated 21.2% of pseudotranslation along 0.667 0.333 0.000.
But MR using phaser gave a dimer in asu which are related by a 2 fold,
so there was no indication of any pseudo translation and protein
is bound to 10-12 cadmiums. Could this off origin peak be due to the
presence of the heavy atoms? how can i rule out the presence of this
pseudotranslation as indicated in sfcheck?
Thanking you
Respectfully
Kavya
On 04/06/2011 05:08 PM, ka...@ssl.serc.iisc.ernet.in wrote:
Dear users,
Is there a possibility that both non-merohedral twinning
and partial hemihedral twinning occur in the same crystal?
In one of the data in R3, sfcheck indicated twinning and thus
upon using twinning option during refinement, refmac considered
twinning operator of (k h -l). But the images also show some
interpenetrating lattice spots which are characteristics of
non-merohedral twinning.
Probably one of the lattices have been more prominent
and hence detected and processed by mosflm with an overall
Rmerge of 8.2 at 2.35 Ang resolution.
So is there such a possibility?
Thanking you
With Regards
Kavya
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