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Re: [ccp4bb] difference density ripples around Hg atoms
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CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: difference density ripples around Hg atoms
From: Bart Hazes bart {- dot -} hazes {- at -} UALBERTA {- dot -} CA
Date: 2007-08-01		Next message:
Subject: Re: difference density ripples around Hg atoms
From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2007-08-01


Subject: Re: difference density ripples around Hg atoms
From: Kevin Jude kjude {- at -} BERKELEY {- dot -} EDU
Date: 2007-08-01

I have seen similar ripples with S-methylmercury cysteine - and an 80
sigma peak for Hg is not that surprising! Anisotropic refinement was
not helpful in reducing the ripples, as it is indeed a summation
problem. It's a good idea to refine occupancy of the Hg, though, and to
look for dual conformations of the cysteines.

best wishes
kmj

Klemens Wild wrote:
> Dear friends of the Fourier transform,
>
> I am refining a structure with 2 adjacent Hg atoms bound to cysteines of
> different monomers in the crystal contacts, which means I need to refine
> them as well. While the structure nicely refines (2.2 A data), I do not
> get rid of negative density ripple layers next to them (-10 sigmas). My
> question: is this likely due to anistropy of the soft mercury atoms
> (anisotropic B refinement decreases the ripples) or is this likely a
> summation truncation effect prominent for heavy atoms? Can I just
> anistropically refine the mercuries while I keep the rest isotropic?
> Never saw this in a PDB. Suggestions are very welcome.
>
> Greetings
>
> Klemens Wild

CCP4bb navigation

CCP4bb <-- 1999 <-- November 1999 <-- 30 November 1999
Previous message:
Subject: Re: difference density ripples around Hg atoms
From: Bart Hazes bart {- dot -} hazes {- at -} UALBERTA {- dot -} CA
Date: 2007-08-01		Next message:
Subject: Re: difference density ripples around Hg atoms
From: James Holton JMHolton {- at -} LBL {- dot -} GOV
Date: 2007-08-01
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