[phenixbb] Strong anomalous signal but AutoSol fails

[Terwilliger, Thomas Charles]

Hi Mohamed,

You might try running phenix.anomalous_signal on your data (may require finding your unmerged data and running phenix.scale_and_merge first).  This will give you an idea if you should be able to solve your SAD dataset.

See:  http://www.phenix-online.org/version_docs/1.10pre-2124/reference/anomalous_signal.html

All the best,
Tom T





From: phenixbb-bounces at phenix-online.org [phenixbb-bounces at phenix-online.org] on behalf of mohamed noor [mohamed.noor34 at gmail.com]

Sent: Thursday, August 06, 2015 3:16 PM

To: PHENIX user mailing list

Subject: [phenixbb] Strong anomalous signal but AutoSol fails



















Dear developers




I have a low resolution anomalous dataset which Aimless suggests has an effective resolution to 3.3 A and anomalous signal to 3.5 A. However, SAD phasing with AutoSol is not successful with the final R factor around 50 %.





I also have another dataset collected at a remote wavelength without anomalous signal to 3 A but they are not isomorphous (> 2 A difference in c axis).






The anomalous signal comes from the ligand heme c, which is bound covalently to the protein, so its occupancy should be 1. The protein is quite small with about 120 residues. Xtriage suggests an NCS of 6 to 20 with most likely number to be 13.




Is there any reason why a reasonable solution cannot be found? There is no twinning.




I am using the latest nightly 1.10 pre2124.




Thanks.