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Re: [ccp4bb]: Refining Ions - Mn+2 Vs Mg+2...



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Partial occupancy, or you really do have Mg2+ (which has the same 
number of electrons as water).

On Thursday, January 30, 2003, at 03:27 PM, raji wrote:

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>
> Hi,
> I am trying to incorporate ions into my model.
> We know from previous data that we have Mn+2 ions in our structure. 
> Most of us
> in the lab who have tried to refine the ions as Mn+2 in CNS
> (as per CNS tutorial) find that the R-factor and R-free increase (as 
> much as
> 1% sometimes) and have continued to refine them as waters.
> It's the same situation whether it's Mn+2 or Mn.
> However, when I tried to refine all my Mn+2 as Mg+2 (by mistake),
> I found that the program handles it nicely and that there is a nice 
> drop in
> R-factor and R-free.
> So, I am currently refining Mn+2 as Mg+2.
> Is there any explanation to what might be going on ? Does something 
> need to be
> done differently to refine them as Mn+2 ions.
> Any words of wisdom/advice/suggestions/criticisms ?
> Thanks very much,
> Raji
>