Dear Tiago,
I asked a few colleagues who are experts in aperiodic and quasi crystals.
Ray Withers replied in the email below.
I converted the ppt file he refers to as a pdf, so it is not so large. Take a look at his analysis there.
Very interesting, so maybe there are more modulated protein crystals out there than we thought.
I also asked Christer Svensson what he thought and
he said "It might of course be something complicated, like a modulation.
But looking at just the first of the pictures, this pattern could be generated
by "twinning" of a hexagonal lattice.
One part of the crystal is rotated (around the 3 or 6-fold axis) about
22 degrees with respect to the other.
It would be a lot easier to judge by doing the indexing."
Christer's program TwinSolve can handle this type of data, you may want
to contact him.
Have fun with it. Gloria
----- Forwarded by Gloria
Borgstahl/Eppley/UNMC/UNEBR on 02/05/2006 08:01 PM -----
| [EMAIL PROTECTED]
02/03/2006 04:55 PM |
|
G'day Gloria,
Very interesting. Looks very much like a so-called triple-q modulated
structure (see the attached .ppt file. This sort of thing sometimes occurs
as a Moire layer stacking effect.
With best wishes,
Ray
Hi Ray, just received your aperiodic email and then this one off the ccp4
> group.
> What do you make of this diffraction? Gloria
>
> ----- Forwarded by Gloria Borgstahl/Eppley/UNMC/UNEBR on 02/03/2006 09:18
> AM -----
>
> Tiago Barros <[EMAIL PROTECTED]>
> Sent by: [EMAIL PROTECTED]
> 02/03/2006 08:59 AM
>
> To
> [email protected]
> cc
>
> Subject
> [ccp4bb]: Curious diffraction pattern - non CCP4 related
>
>
>
>
>
>
> *** For details on how to be removed from this list visit the ***
> *** CCP4 home page http://www.ccp4.ac.uk ***
>
>
> Dear all,
>
> I would like to share with you a very strange diffraction pattern
> that I recently collected at the SLS.
>
> You can have a look at some pictures of this diffraction pattern here:
>
> http://tiagobarros.home.sapo.pt/zoom_in.png
>
> http://tiagobarros.home.sapo.pt/45.png (45 degrees)
>
> http://tiagobarros.home.sapo.pt/90.png
>
> http://tiagobarros.home.sapo.pt/135.png
>
> Some additional information. These happened with just one of my
> crystals. I know from previous experience that my crystals (from a
> membrane protein) are made of stacks of 2D crystals (SG P321). This
> stacking is very often not that ordered, which leads to different
> layers with different orientation within the same crystal. The space
> group of my crystals is usually either C2 or P3121.
>
> I've found these circular motif of spots very curious, and I don't
> really have a good explanation for them.
>
> Any idea of what might have caused this?
>
> Thank you.
>
> Tiago
>
>
> ************************************************************************
> *
>
> Tiago Barros
> Max-Planck Institute of Biophysics
> Dept. of Structural Biology
> Max-von-Laue Str. 3
> D-60438 Frankfurt
> Germany
>
> tel: +49-69-6303-3055
>
> ************************************************************************
> *
>
>
>
>
>
[attachment "Gloria.ppt" deleted by Gloria Borgstahl/Eppley/UNMC/UNEBR]
