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
> <[log in to unmask]> 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: [log in to unmask]
>> 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: [log in to unmask]
>> 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: [log in to unmask]
WWW: www.genzentrum.lmu.de
*******************************************************
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