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Re: [ccp4bb] unbiased electron density map
 

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CCP4bb <-- 2008 <-- January 2008 <-- 10 January 2008
Previous message:
Subject: Re: bond lengths, angles, ideality and refinements
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10 		Next message:
Subject: Re: ideal bond length and bong angel
From: Gerard DVD Kleywegt gerard {- at -} XRAY {- dot -} BMC {- dot -} UU {- dot -} SE
Date: 2008-01-10


Subject: Re: unbiased electron density map
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10

Am 10.01.2008 um 01:53 schrieb Dale Tronrud:
...
> Your quote bring up another matter. An "initial" map, i.e. before
> refinement, is unbiased if it is an omit map. If you have done no
> refinement and you leave the interesting part out of the calculation
> of Fc there can not be any bias in either the Fo-Fc or the 2Fo-Fc map.
> This is why an initial map is more reliable for proving binding of
> a compound, for example, than a bias reduced map after refinement.
...

But isn't this only true, if the model that is put in was not refined
against a related data set before? If the new Fobs are related to the
old Fobs (against which the model was refined before) then you carry
any model bias over to the new data, because a simple omit-map using
the old data will have model bias.

Best regards,

Dirk.

*******************************************************
Dirk Kostrewa
Gene Center, A 5.07
Ludwig-Maximilians-University
Feodor-Lynen-Str. 25
81377 Munich
Germany
Phone: +49-89-2180-76845
Fax: +49-89-2180-76999
E-mail: kostrewa@lmb.uni-muenchen.de
*******************************************************



CCP4bb navigation

CCP4bb <-- 2008 <-- January 2008 <-- 10 January 2008
Previous message:
Subject: Re: bond lengths, angles, ideality and refinements
From: Dirk Kostrewa kostrewa {- at -} LMB {- dot -} UNI-MUENCHEN {- dot -} DE
Date: 2008-01-10 		Next message:
Subject: Re: ideal bond length and bong angel
From: Gerard DVD Kleywegt gerard {- at -} XRAY {- dot -} BMC {- dot -} UU {- dot -} SE
Date: 2008-01-10


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