Hi all

Sticking to the first question, if you don't restrict yourself to _X-ray_ 
crystallography but use your local neutron source instead, it should be 
straightforward (subject to all the normal caveats).

On 10 Nov 2016, at 23:02, Tim Gruene wrote:

> Dear JPK,
> 
> to answer your first question, at atomic resolution you would notice a 
> density 
> difference between N and C. At a little less resolution you might still 
> measure difference in bond length.  
> 
> Regrds,
> Tim
> 
> On Thursday, November 10, 2016 8:41:43 PM CET Keller, Jacob wrote:
>> Dear Crystallographers,
>> 
>> I don't think there is any feasible way crystallographically to distinguish
>> between nitrate and carbonate or bicarbonate-correct? But that is not my
>> main question.
>> 
>> My main question is: given that nitrate and carbonate are both very
>> important and also very different physiologically, and therefore they must
>> be distinguished/recognized by cells, how is this done, since the ions are
>> so similar in structure? Is there some aspect of these ions that differs
>> dramatically of which I am not aware? What kind of "handles" could a
>> protein grab onto to distinguish between nitrate and carbonate/bicarbonate?
>> 
>> JPK
>> 
>> 
>> *******************************************
>> Jacob Pearson Keller, PhD
>> Research Scientist
>> HHMI Janelia Research Campus / Looger lab
>> Phone: (571)209-4000 x3159
>> Email: [email protected]<mailto:[email protected]>
>> *******************************************
> 
> 
> -- 
> --
> Paul Scherrer Institut
> Tim Gruene
> - persoenlich -
> OFLC/102
> CH-5232 Villigen PSI
> phone: +41 (0)56 310 5297
> 
> GPG Key ID = A46BEE1A

Harry
--
Dr Harry Powell
Chairman of International Union of Crystallography Commission on 
Crystallographic Computing
Chairman of European Crystallographic Association SIG9 (Crystallographic 
Computing) 











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