Dear Nicolas,

The way this is supposed to work, Cda should be assigned to Hda*, Cdb to 
Hdb*, and the program should make sure of this behind the scenes, renaming 
Cdb to Cda when necessary. So something is wrong. It could be with the 
program, or it could be with the data.

I do not know if you already did this, but I recommend goint into 
M:Assignment:Quality Reports {Resonances} and checking your funny 
resonances. Are they coloured red, showing there is a problem? What does 
it say? When you have something that is coloured red in one of the first 
four columns (#, Iso.. Resonance, Bound), you should select it and click 
[Show Peaks]. That gives you a list of all the poeaks where this Resonance 
is assigned. You can then check if the assignments are consistent, and 
which assignment comes form where.

A common source of problems is when some experiment type is set wrong. A 
3D HCCH-TOCSY, can be either Hc_CH.relayed or HC_cH,relayed, a 3D 
HSQC-NOESY can be either H[C]_H.through-space or H_H[C].through-space. The 
difference is in which of the proton dimensions is bound to the carbon and 
which is not. If you get one experiment wrong like that you will get a lot 
of assignmetns wrong. Or you could simply have some incorrect assignments, 
it is not unheard of.

Try having a look and see if you get any information about what is going 
on, and if it does not help send us another mail.

YOurs,

Rasmus

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Dr. Rasmus H. Fogh                  Email: [log in to unmask]
Dept. of Biochemistry, University of Cambridge,
80 Tennis Court Road, Cambridge CB2 1GA, UK.     FAX (01223)766002

On Fri, 23 Mar 2012, Nicolas JEAN wrote:

> Dear all,
>
> I have noticed in my CcpN project that CcpNmr (Analysis 2.2.1) doesn't assign 
> correctly most of my Leu Hδs with their respective Leu Cδs in my non 
> stereospecific assignment. For example, for a Cδ-Hδ pair (from a given 
> residue), the software assign the carbon "Cδa" and its respective proton 
> "Hδb" instead of "Hδa". So finally I have some Cδa-Hδb and Cδb-Hδa pairs, 
> which are confusing for the structure calculation step.
>
> In some other cases (still for Leu residues), the software gives the right 
> assignment for the carbon associated to its Hδ (i.e : "Cδa" for the one 
> linked to "Hδa"), but also gives the same name to the other carbon (which 
> should be "Cδb", as it is linked to the "Hδb" for example, instead of "Cδa"), 
> with the result that I eventually get 2 distinct resonances in CCPNmr called 
> Cδa (or Cδb).
>
> I tried to de-assign and reassign both Hδ and both Cδ, assign them in another 
> order, but CcpNmr always makes the same assignment choice than before.
>
> I have also noticed the same issues for the Valine Cγs and Hγs.
>
> Does anyone know how to solve it? Thank you for your help.
>
> Nicolas JEAN
>