I agree with Pavel... if you got so many observations you dont need TLS but use anisotropic adps. What I want to add is the dangerous comment to "cutting back data ... to improve Rfact" Of course, if you lower the amount of observations while keeping the parameters to fit constant will lower your R facts. That doesnt necessarily mean you improve your model. It just means that you incase the param to obs ratio - which says nothing about the accuracy of your model...
Dr. Matthias Barone AG Kuehne, Rational Drug Design Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Robert-Rössle-Strasse 10 13125 Berlin Germany Phone: +49 (0)30 94793-284 ________________________________ From: CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> on behalf of Pavel Afonine <pafon...@gmail.com> Sent: Wednesday, October 10, 2018 11:03:49 AM To: CCP4BB@JISCMAIL.AC.UK Subject: Re: [ccp4bb] Issue with high Rfree (0.25) for a high-resolution dataset (1.05 Ang) Hi Tony, I always feel some people are too "greedy" with the resolution they want to achieve. I mostly find that extremely high density is a pain to work with as it's usually accompanied by many dual, triple conformers, a lot of noise in the solvent phase that is often difficult to interpret, etc... Often you spend more time on a high resolution structure that clearly shows your protein, as opposed to a low resolution structure where it's difficult to interpret parts of the map. Also, in most cases you REALLY don't need a 1 Ang map to clearly show the overall structure of your protein, ligands, first shell of solvent molecules on the surface of your protein, etc... higher resolution typically means you have a chance to obtain a more accurate atomic model of a crystal structure, which in turn may lead to a more accurate interpretation of this model. I fully agree that high resolution requires more modeling effort. There is still a great room for software developers to provide more automation. Your completeness is 90% in your high resolution shell, which is fine, but have you checked you can clearly see most reflections for h, k and l? Maybe you're missing many reflections for one of them. I would at least try cutting your data back to 1.1 or 1.2 Ang, as it might dramatically improve your R factors and still show everything you want to show. Also, did you try TLS refinement? At resolutions like 1.2A or better one normally models ADPs as anisotropic for all atoms (except H), so no need to use TLS. Pavel ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1 ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
