Dear Igor,
Hb* behaves exactly like you describe. It is simply a shorthand way of
saying 'both Hb2 and Hb3 are at this frequency'. There is no connection
between the two resonances once they are created. There is no difference
between using Hb* and creating Hb2 and Hb3 separately.
The reason for this is that we assign resonaces to stereospecific atoms,
possbly with some ambiguity. We cannot assign a single resonance to both
Hb2 and Hb3 at the same time. We could do it if Hb2 and Hb3 were in fast
exchange, like CH3 protons, but they are not. So we decided to leave 'Hb*'
in as a shortcut insterad fo removing it altogether.
I hope this helps.
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 Wed, 7 Jun 2006, igor barsukov wrote:
> Hi,
>
> Can somebody clarify the use of ambiguous assignments for CH2 groups,
> please. If I create a new resonance in peak assignment popup and use,
> for example, Hb* to assign it, an additional resonance will be created
> and one resonance will be assigned to Hb2 and the other to Hb3 proton.
> After that both resonances appear to be independent. I can add or remove
> them separately as contributions to peaks, deassign one of them and so
> on. Is there a connection between them, and if there is, what effect it
> has. What is the difference of using Hb* as opposite to creating two
> resonances and assigning one to Hb2 and the other to Hb3.
>
> Thanks
> Igor
>
> --
> Dr. Igor Barsukov
>
> Biological NMR Centre,
> University of Leicester
> PO Box 138,
> University Road,
> Henry Wellcome Building,
> Leicester LE1 9HN
> UK
> E-mail: [log in to unmask]
> Tel: +44 (0)116 229 7098
> FAX: +44 (0)116 229 7053
>
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