| Quick navigation: | Home | Site Map || References | Biography || Copyright | Other copyright | Contact us | | |
|
|
Re: [ccp4bb] an over refined structure |
|
CCP4bb navigationCCP4bb <-- 2008 <-- February 2008 <-- 04 February 2008Subject: Re: an over refined structure From: Tim Gruene tg {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE Date: 2008-02-04 others have published analytical expressions for how to estimate the ratio between R and Rfree, just google for "tickle rfree" to find the references. You easily achieve a large difference by adding too many waters which just model noise. There may be other reasons for which more knowledge about the structure is required. Do you have large unmodelled regions, like loops that do not show in the density map? Tim -- Tim Gruene Institut fuer anorganische Chemie Tammannstr. 4 D-37077 Goettingen GPG Key ID = A46BEE1A On Mon, 4 Feb 2008, Sun Tang wrote: > Hello All, > > I refined a structure with Refmac in CCP4i and the R/Rfree is 0.215/0.277. The difference between R and Rfree is too much even though I used 0.01 for weighting term in the refinement (the default value is 0.3). The RMSD for bond length and bond angle is 0.016 A and 1.7 degree. > > What may be wrong with the over-refined structure? What is the reason for leading to an over-refined structure? How to avoid it? > > Best wishes, > > Sun Tang > > > --------------------------------- > Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. CCP4bb navigationCCP4bb <-- 2008 <-- February 2008 <-- 04 February 2008 |
| ProteinCrystallography.org: Copyright 2006-2008 by Quid United Ltd |