I am not sure anyone looks at plain 2fo-fc maps anymore - it almost always (at least since the beginning of the 3rd millennium) implies 2mfo-Dfc ML maps. Detailed explanation of coefficients and their relation to ML sigma A are in R.Read papers, BMC, Bricogne, etc pp BR,
On Tue, Apr 10, 2012 at 8:38 AM, Tim Gruene <[email protected]> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Dear Francis, > > the phases calculated from the model affect the whole unit cell hence it > is more likely this is real(-space, local) disorder rather than poor > phases. > > Regards, > Tim > > P.S.: The author should not look at an 2fofc-map but a > sigma-A-weighted map to reduce model bias. > > On 04/10/12 17:22, Francis E Reyes wrote: > > Hi all, > > > > Assume that the diffraction resolution is low (say 3.0A or worse) > > and the model (a high resolution homologue, from 2A xray data is > > available) was docked into experimental phases (say 4A or worse) > > and extended to the 3.0A data using refinement (the high resolution > > model as a source of restraints). There are some conformational > > differences between the high resolution model and the target > > crystal. > > > > The author observes that in the 2fofc map at 3A, most of the model > > shows reasonable density, but for a stretch of backbone the > > density is weak. > > > > Is the weakness of the density in this region because of disorder > > or bad model phases? > > > > > > Would love people's thoughts on this one, > > > > F > > > > > > --------------------------------------------- Francis E. Reyes > > M.Sc. 215 UCB University of Colorado at Boulder > > > > - -- > - -- > Dr Tim Gruene > Institut fuer anorganische Chemie > Tammannstr. 4 > D-37077 Goettingen > > GPG Key ID = A46BEE1A > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.12 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iD8DBQFPhFP3UxlJ7aRr7hoRAj4HAKDpHCsN+tBKhDAcOYmIe5c58ThG+gCeMujG > pAJxRNuJHE4+oFRPSYx4bnc= > =s3uw > -----END PGP SIGNATURE----- > -- ----------------------------------------------------------------- Bernhard Rupp (Hofkristallrat a. D) 001 (925) 209-7429 +43 (676) 571-0536 [email protected] [email protected] http://www.ruppweb.org/ ----------------------------------------------------------------- The hard part about playing chicken is to know when to flinch -----------------------------------------------------------------
