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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 *******************************************************