1H-15N CSP calculation

Analysis Version 3
1

Hi,
I am trying to compare two HSQC spectra. A reference and after addition of a ligand. The CSP values I get are different to those when I calculate it manually.
I am using the equation form here: Titrations.
If I set a to 1 for 15N the calculation is correct. Therefore it looks like the a weighting factor for 15N is not applied correctly. Values are significantly different with 0.222 ppm when I calculate it and 0.141 for CCPN V3.

thanks,
Ken

2

Hi,
I have double checked and their is a mistake in the Williamson (2013) paper in equation 8 that I was using. His eqn 9 matches the one you are using and the calculations look fine. Phew!
thanks,
Ken

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