[Xplor-nih] carbon chemical shift error

[John Kuszewski]

Hi,

I presume you're asking about the CARBonshift energy term.

Do you mean you want to define an error in your observed Ca or Cb  
chemical shifts?  If so, you can't.  The term's accuracy in  
predicting carbon shifts from backbone torsion angles is rather low  
(~ 1ppm, if I remember correctly) compared to the accuracy of  
measurement of Ca and Cb chemical shifts, so there's no point in  
defining a squarewell that way.

Rather, the carbonshift's squarewell potential works by comparing the  
difference between observed and expected shift values relative to the  
known accuracy of the prediction surface at each point.  These  
accuracies are recorded in the same table as the expected secondary  
chemical shifts.

So all you need to do is turn on the square well potential shape by  
calling CARBon SQUArewell, and you're all set.

If I've misunderstood your question, forgive me.

--JK

On Jan 17, 2008, at 5:00 PM, Irina Nesmelova wrote:

> Hello,
>
> How can I input the error for carbon chemical shift?
> Thank you,
> Irina.
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> Xplor-nih mailing list
> Xplor-nih at nmr.cit.nih.gov
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