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<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Hi everyone,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>I have a data set to 2.8A, with most likely 2 molecules in
the asu and a molecular replacement model with 40% sequence identity. (Cell 71.3
71.3 227.9 90 90 90)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Initially the data appeared to be either P4322 or P43212
(Rsym = 7.4%; Cell 71.3 71.3 227.9 90 90 90), but the molecular replacement
solutions had major clashes with the symmetry related molecules and a lower LLG
for the solution of the second molecule. No twinning was detected by Xtriage.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Processing the data in P212121 (Rsym 5.6%, cell 71.3 71.4
228.2 90 90 90) gave me a better molecular replacement solution (LLG 121/373),
but I had 5 clashes with the second molecule in the asu. (I tested all
alternative spacegroups) <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>I also have a MAD dataset (very low quality!) and I combined
the phases with the one obtained from molecular replacement in Sharp. After NCS
averaging the maps had improved (still not great). I tried to improve things in
the model and run Phaser again and the solution had better statistics (LLG
338/1223) and the clashes were reduced to 2. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Xtriage detected pseudo-merohedral twinning with a twin fraction
of 43% with twin operator –k, -h, -l. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>So I tried refining the model with phenix telling it the twinning
operator and fraction, but R/Rfree are stuck around 45%. I also tried simulated
annealing but that gave even higher R/Rfree. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Is there anything I can do, or is it a hopeless case? <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Thanks for your help in advance!<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Verdana><span style='font-size:10.0pt;
font-family:Verdana'>Sabine<o:p></o:p></span></font></p>
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