Hi Rhys, all three structures are at modest resolution and they don't seem to be properly refined. At least they are all below average. I wonder how this paper made it past the referees.
I haven't checked the paper, but there are ways and means how to deal with weakly bound ligands in the best possible way. One aspect is to improve the phases as much as possible without having the ligand present. This was obviously NOT done. Another way is to use the PANDDA approach, which relies on having many data sets available. I suppose that this was also not done. The best way to check is to delete the ligand and so some extensive refinement in order to remove the phase bias introduced by the ligand. Only then you can reliably assess whether something is there or not. Cheers, Manfred Am 19.07.2019 um 15:21 schrieb Rhys Grinter: Hi All, I was chatting with a colleague during a recent synchrotron visit and they'd recently come across some ligand/drug bound structures associated with a paper recently published in a high impact factor journal. They had pulled the associated SFs from the PDB and found that the electron density associated with these ligands didn't match that reported in the paper and certainly wasn't sufficient to model the alleged ligand. I also pulled the structure factors and after refinement in the presence/absence of the alleged ligand I also feel that the density present does not warrant modelling of the ligand. I was hoping that the community might be able to give me an outside opinion on these datasets (PDB IDs: 6MO0, 6MO1, 6MO2) and if the problem associated with the data is verified, provide some advice on how to proceed. This isn't the first occasion I've seen ligand bound structures with questionable density deposited in association with papers in well respected journals. Despite improvements to validation I feel that this problem is widespread. Best Regards, Rhys -- Dr Rhys Grinter NHMRC Postdoctoral Researcher Monash University +61 (0)3 9902 9213 +61 (0)403 896 767 ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 -- Dr. Manfred S. Weiss Macromolecular Crystallography Helmholtz-Zentrum Berlin Albert-Einstein-Str. 15 D-12489 Berlin Germany ________________________________ Helmholtz-Zentrum Berlin für Materialien und Energie GmbH Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V. Aufsichtsrat: Vorsitzender Dr. Volkmar Dietz, stv. Vorsitzende Dr. Jutta Koch-Unterseher Geschäftsführung: Prof. Dr. Bernd Rech (Sprecher), Prof. Dr. Jan Lüning, Thomas Frederking Sitz Berlin, AG Charlottenburg, 89 HRB 5583 Postadresse: Hahn-Meitner-Platz 1 D-14109 Berlin ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
