Re: [ccp4bb] Refmac unrestrained refinement on ligands only

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

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Subject: Re: Small lysozyme crystals protocol
From: "David J {- dot -} Schuller" djs63 {- at -} CORNELL {- dot -} EDU
Date: 2008-07-04

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Subject: Re: Refmac unrestrained refinement on ligands only
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2008-07-04

It would be possible with a bit of effort to apply such mixed restraints
using SHELXL. However I'm not convinced that it is such a good idea, at
the resolutions you are working at the geometry of the core regions will
be primarily determined by the X-ray data anyway. Perhaps what we
really need are B-value dependent distance and other restraints, so they
are tighter if the B-values are higher and vice versa.

George

Prof. George M. Sheldrick FRS
Dept. Structural Chemistry,
University of Goettingen,
Tammannstr. 4,
D37077 Goettingen, Germany
Tel. +49-551-39-3021 or -3068
Fax. +49-551-39-22582

On Fri, 4 Jul 2008, Matthew BOWLER wrote:

> Dear All,
> I have looked everywhere for answers on this one with no luck... I have
> several structures at reasonable resolution 1.7 to 1.1A. I have performed
> unrestrained refinement on the model which is fine for the core protein and
> ligands but the surface atoms start flying off a bit. So what I would like to
> do is unrestrained refinement only on the ligands and leave the protein
> restraints in place. I have a feeling that if I cannot do it in Refmac I
> can in phenix but I cannot find anything out about that either. All help
> greatly appreciated, yours, Matt.
>
>
> --
> Matthew Bowler
> Macromolecular Crystallography Group
> European Synchrotron Radiation Facility
> B.P. 220, 6 rue Jules Horowitz
> F-38043 GRENOBLE CEDEX
> FRANCE
> =============================================================================
> Tel: +33 (0) 4.76.88.29.28
> Fax: +33 (0) 4.76.88.29.04
>
> http://www.esrf.fr/UsersAndScience/Experiments/MX/About_our_beamlines/ID14-2/
> =============================================================================
>
>

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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999

Previous message:
Subject: Re: Small lysozyme crystals protocol
From: "David J {- dot -} Schuller" djs63 {- at -} CORNELL {- dot -} EDU
Date: 2008-07-04

Next message:
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From: Andreas_Förster docandreas {- at -} GMAIL {- dot -} COM
Date: 2008-07-04