I think Jacob is right. As long as protein crystals contain about 10% "dark matter"* not accounted for in any model, we cannot fake a "true" electron density map and it is then not surprising that an 2mFo-DFc map is closer to a model-based fake map than a map based on experimental phases. HS
*This "dark matter" causes the best Rfactors for protein crystals to be ~15% instead of the 5% measurement errors and may include disorder, anisotropy, imperfectly modelled solvent etc. -----Ursprüngliche Nachricht----- Von: CCP4 bulletin board [mailto:[email protected]] Im Auftrag von Keller, Jacob Gesendet: Donnerstag, 6. Dezember 2018 04:37 An: [email protected] Betreff: [EXTERNAL] Re: [ccp4bb] Experimental phasing vs molecular replacement >>That said, model phases are not so bad. In fact, in all my experiments with >>fake data the model-phased 2mFo-DFc map always has the best correlation to >>the "true" map. If you substitute the "true" phases and use the 2mFo-DFc >>coefficients you actually make things worse. Counter-intuitive, but true. I don't understand what you mean by true and fake here--can you clarify? How are the true map and phases generated (from an original true model, I assume?), and how are the fake data generated? (Also from the true model?) I am wondering whether there is some circular reasoning? JPK ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://urldefense.proofpoint.com/v2/url?u=https-3A__www.jiscmail.ac.uk_cgi-2Dbin_webadmin-3FSUBED1-3DCCP4BB-26A-3D1&d=DwIGaQ&c=Dbf9zoswcQ-CRvvI7VX5j3HvibIuT3ZiarcKl5qtMPo&r=HK-CY_tL8CLLA93vdywyu3qI70R4H8oHzZyRHMQu1AQ&m=YVXLK5IxGDpGCJovdCIRO5XSyyWR2c5GBj-Y2IPJ70s&s=AToqUF-6D9-eKOMC6YEFZWDNRgry_hBzKtpNklyB57w&e= ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
