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: marina....@pharmazie.uni-marburg.de
http://www.agklebe.de/
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