Hi Ian,
o yes, I didn't work out the particular case that Francis Reyes was
asking for, but intended to give a more general idea where additional
twofold NCS axes could come from, by a combination of a NCS axis
perpendicular to a crystallographic twofold axis. The image should just
support this. I hope, that with this pointer, Francis Reyes will be able
to work out how the self-rotation function peaks are related.
Cheers,
Dirk.
Am 19.03.10 15:12, schrieb Ian Tickle:
Dirk, I'm not sure this is right, the NCS 2-folds clearly occur at phi
= 45, 135 ..., not at phi = 30, 150 ... as required by your
explanation. Also you haven't explained the very clear peaks near
theta = 45, phi = 0. 90 ... . I won't be convinced until I see the
results from RFCORR!
Cheers
-- Ian
On Fri, Mar 19, 2010 at 9:47 AM, Dirk Kostrewa
<kostr...@genzentrum.lmu.de> wrote:
... and here a slightly clearer version where I numbered the NCS-related
positions 1,2,3 and their crystallographic equivalent positions 1',2',3',
which makes the NCS dyads a bit easier to understand ...
Sorry for sending two pictures.
Best regards,
Dirk.
Am 19.03.10 10:31, schrieb Dirk Kostrewa:
Dear Francis Reyes,
from the self-rotation function at kappa=120 degrees, you can see that one
threefold NCS axis is perpendicular to a crystallographic twofold axis. I
haven't worked this out for your particular case, but the combination of a
threefold (n-fold) NCS axis perpendicular to a crystallographic twofold axis
creates three (n) NCS twofold axes (that can be viewed from both directions
and in case of an uneven NCS axis appear "twice"). I've appended a schematic
stereographic projection to make this a bit clearer (full dyad symbol
crystallographic, open dyad and triangle symbols NCS, green circles
positions above plane, red circles positions below plane created by
crystallographic dyad, dashed lines help to visualize the NCS threefold,
thick solid line crystallographic twofold, thin solid lines NCS twofolds).
Good luck,
Dirk.
Am 18.03.10 16:03, schrieb Francis E Reyes:
Hi all
I have a solved structure that crystallizes as a trimer to a reasonable
R/Rfree, but I'm trying to rationalize the peaks in my self rotation. The
space group is P212121, calculating my self rotations from 50-3A,
integration radius of 22 (the radius of my molecule is about 44). I can see
the three fold NCS from my structure on the 120 slice, but I'm trying to
rationalize apparent two folds in my kappa=180. A picture of both slices is
enclosed. The non crystallographic peaks for kappa=180, P222 begin to appear
at kappa=150 and are strongest on the 180 slice.
My molecule looks close to a bagel (44A wide and 28A tall). The three fold
NCS is down the axis of looking down on the bagel hole. I'm trying to find
the two fold. I imagine it could be slicing the bagel in half (like to eat
it for yourself) or slicing it vertically (like to share amongst kids) but
I'm not exactly sure what's the best way to visualize this. Is there
something easier than correlation maps with getax (since I have the rotation
(polarrfn) and translation?). If you have an eye for spotting symmetry, Ill
send the pdb in confidence.
Thanks!
FR
---------------------------------------------
Francis Reyes M.Sc.
215 UCB
University of Colorado at Boulder
gpg --keyserver pgp.mit.edu --recv-keys 67BA8D5D
8AE2 F2F4 90F7 9640 28BC 686F 78FD 6669 67BA 8D5D
--
*******************************************************
Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: kostr...@genzentrum.lmu.de
WWW: www.genzentrum.lmu.de
*******************************************************
--
*******************************************************
Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: kostr...@genzentrum.lmu.de
WWW: www.genzentrum.lmu.de
*******************************************************
--
*******************************************************
Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: kostr...@genzentrum.lmu.de
WWW: www.genzentrum.lmu.de
*******************************************************
