Protonation of fosfate would be better. I've never seen sulfate as a
H-bond donor. But maybe the amide needs to be flipped.
cheers,
Hans
Chris Fage schreef op 2016-03-20 21:05:
> Dear All,
>
> A sulfate ion appears to fit well into a blob of my electron density
> (please see image at
> https://drive.google.com/file/d/0B6ny9TrPnOP8YWRXcUZZa2VqaUU/view?usp=sharing).
> Water is too small to account for the density and the coordination
> number is too low for a monatomic ion (I have labeled distances to the
> closest atoms; all others are >3.9 angstroms away). I wonder if
> sulfate could originate from the M9 minimal media in which the protein
> was expressed. Has anyone else observed this? There is no sulfate in
> the crystallization condition or protein solution. A physiological
> role for sulfate is also unlikely for this enzyme.
>
> Thank you.
>
> Kind regards,
> Chris
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