Dear Marina,
Just an observation from my side: if you are able to process your data in P622, there must be some 2-fold perpendicular to l, which would most likely be a non-crystallographic or a twinning axis. Is there a NCS 2-fold in the P321 data set you solved? If so, is it perpendicular to l? If not, there must be some twinning law that converts l into -l like -k,-h,-l
Also, careful analysis of your solved P321 structure could give some hints how the twinning might look like.
Best,
Herman
-----Ursprüngliche Nachricht-----
Von: CCP4 bulletin board [mailto:[log in to unmask]] Im Auftrag von Marina Ley
Gesendet: Donnerstag, 11. Juli 2019 12:50
An: [log in to unmask]
Betreff: [EXTERNAL] [ccp4bb] twinning problems
EXTERNAL : Real sender is [log in to unmask]
Hello everyone,
I have the following problem:
I have some really good data sets of about 1.6 A which could be
processed in P 6 2 2 as well as in P 3 2 1.
Intensity statistics tests indicate twinning (merohedral, twinning
law: -h, -k, l, in P 3 2 1).
But I did not find a good MR solution (R value around 60%) and when I
try to refine it with the twin law I get really bad maps.
However I could get one data set where the intensity statistics tests
did not indicate twinning and I have already managed to solve the
structure.
SPACE_GROUP_NUMBER: 154 (P 3 (2) 2 1)
UNIT_CELL_CONSTANTS: 57.56 57.56 159.98 90.000 90.000 120.000
number of molecules in asymmetric unit: 2
NCS: yes
I could see a lot of amino acids in the electron density which were
not in the search model.
But it seems like most of my crystals are twinned. For a fragment
screen which I would like to do I need to solve the twinned data sets,
otherwise I have to search again for another crystallization condition.
I don't know what to do next to solve the twinned data sets. Do you
have any ideas or suggestions?
Thanks in advance!!!
Cheers,
Marina
Some information about the results from Xtriage:
----------Statistics independent of twin laws----------
<I^2>/<I>^2 : 1.586 (untwinned: 2.0, perfect twin: 1.5)
<F>^2/<F^2> : 0.870 (untwinned: 0.785, perfect twin: 0.885)
<|E^2-1|> : 0.564 (untwinned: 0.736, perfect twin: 0.541)
<|L|> : 0.380 (untwinned: 0.500; perfect twin: 0.375)
<L^2> : 0.208 (untwinned: 0.333; perfect twin: 0.200)
Multivariate Z score L-test: 12.491
--
Marina Ley
PhD Student, Research Group Professor Dr. Klebe
Department of Pharmaceutical Chemistry
Philipps-University Marburg
Marbacher Weg 6, 35032 Marburg, Germany
Phone: +49 6421 28 21392
E-Mail: [log in to unmask]
https://urldefense.proofpoint.com/v2/url?u=http-3A__www.agklebe.de_&d=DwIBaQ&c=Dbf9zoswcQ-CRvvI7VX5j3HvibIuT3ZiarcKl5qtMPo&r=HK-CY_tL8CLLA93vdywyu3qI70R4H8oHzZyRHMQu1AQ&m=O01KIRRRZ9Krf6AS9sPy8bgILSyqYf592SmrmmH_H6I&s=OiBXd3CAqkfdaGH-2fS0EaH-dsY6ThKMKfqCYqiskZE&e=
########################################################################
To unsubscribe from the CCP4BB list, click the following link:
https://urldefense.proofpoint.com/v2/url?u=https-3A__www.jiscmail.ac.uk_cgi-2Dbin_webadmin-3FSUBED1-3DCCP4BB-26A-3D1&d=DwIBaQ&c=Dbf9zoswcQ-CRvvI7VX5j3HvibIuT3ZiarcKl5qtMPo&r=HK-CY_tL8CLLA93vdywyu3qI70R4H8oHzZyRHMQu1AQ&m=O01KIRRRZ9Krf6AS9sPy8bgILSyqYf592SmrmmH_H6I&s=2E7Nx3y6NmEuT6FMtimCqLVG-RWhPaYfAMJwFMff_5c&e=
########################################################################
To unsubscribe from the CCP4BB list, click the following link:
https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
|