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Re: [ccp4bb] Sulfate ion on 2-fold axis
 

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CCP4bb <-- 2008 <-- January 2008 <-- 11 January 2008
Previous message:
Subject: Re: scale data with multiple MTZ files
From: Roger Rowlett rrowlett {- at -} MAIL {- dot -} COLGATE {- dot -} EDU
Date: 2008-01-10 		Next message:
Subject: International Workshop on “Structural and Molecular Biology of Host Pathogen Interactions”?
From: Gordon Leonard gordon {- dot -} leonard {- at -} ESRF {- dot -} FR
Date: 2008-01-11


Subject: Re: Sulfate ion on 2-fold axis
From: "George M {- dot -} Sheldrick" gsheldr {- at -} SHELX {- dot -} UNI-AC {- dot -} GWDG {- dot -} DE
Date: 2008-01-11
Using SHELXL, restraints can be applied to symmetry equivalent atoms
so one can easily restrain the sulphate to be a regular tetrahedron by
restraining the S-O distances to be equal and the O1..O2, O1'..O2 etc.
distances to be equal (with or without target values). For details of
a similar example see Acta Cryst. A64 (2008) 112-122. From Eleanor's
comment it appears that REFMAC can now do this too, though I was not
aware of the facility. If you then wish to refine S anisotropically
SHELXL will also automatically generate and apply the constraints
required for the special position (in any space group), this can be
very useful for high-resolution refinements.

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. +49-551-39-2582


On Fri, 11 Jan 2008, Charlie Bond wrote:

> Eleanor Dodson wrote:
> > It should be more or less equivalent, but better I think to put 1S at
> > 0.5 occ and 2O at occ = 1
> >
> > At least in REFMAC the restraints to the symmetry atoms should be set up
>
> But if you do that, some of the bond angles will be unrestrained, won't
> they?: O1-S-O2 will be OK, but O1-S-O1' and O2-S-O2' will not. Or is
> refmac cleverer than I think?
>
> Cheers,
> Charlie
> --
> Charlie Bond
> Professorial Fellow
> University of Western Australia
> School of Biomedical, Biomolecular and Chemical Sciences
> M310
> 35 Stirling Highway
> Crawley WA 6009
> Australia
> Charles.Bond@uwa.edu.au
> +61 8 6488 4406
>

CCP4bb navigation

CCP4bb <-- 2008 <-- January 2008 <-- 11 January 2008
Previous message:
Subject: Re: scale data with multiple MTZ files
From: Roger Rowlett rrowlett {- at -} MAIL {- dot -} COLGATE {- dot -} EDU
Date: 2008-01-10 		Next message:
Subject: International Workshop on “Structural and Molecular Biology of Host Pathogen Interactions”?
From: Gordon Leonard gordon {- dot -} leonard {- at -} ESRF {- dot -} FR
Date: 2008-01-11


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