Dear Daniel
Is the omit map for the model with and without the zinc ions possible to confirm
its existence? I am curious. What is the resolution of dataset?
stephen
Quoting Daniel Bonsor <[log in to unmask]>:
> Hello again
>
> I currently have some unexplained density in my structure. As you can
> hopefully see from the images (see file), the density is dumbbell shaped.
> Whatever it is, it is coordinated by Asp and Glu residues. To me it looks
> like each lobe is a ring structure.
>
>
> The crystallization condition was:
> 6.5% PEG 8K, 10mM ZnSO4, 100mM sodium cacodylate pH 6.5, 100mM Am2SO4, 1%
> glycerol, with 20% glycerol as cryo.
> Protein was originally in 50mM Tris, 50mM NaCl pH 7.5.
>
>
> I originally placed a single Zn at the center of each lobe. Though after
> refmac, the Zn was displaced to one side. Two zincs in each dumbbell may have
> worked, but I am dubious about two zinc atoms being 4A apart and there is
> still some unexplained density. Are there any possible cyclization reactions
> of Tris, cacodylate or glycerol may have undergone to explain the density? Or
> is it simply a highly ordered water network? Or is there some other
> explanation?
>
> Thanks in advance
>
> Dan
>
--
Dr. Stephen Sin-Yin Chui
Research Assistant Professor,
Department of Chemistry,
The University of Hong Kong, Pokfulam Road,
Hong Kong SAR, China.
Tel: 22415814 (Office), 22415818 (X-ray Diffraction Laboratory)
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