Dear Elias, I agree with Rasmus that current chemical shift predictions from structure are not accurate enough at present to assign 15N HSQCs, at least not directly. Predictions from the two servers I'm most familiar with (http://www.shiftx2.ca/ and https://spin.niddk.nih.gov/bax/nmrserver/sparta/) have a standard deviation of roughly 0.5 ppm in proton and 2.5 ppm in nitrogen, which is too much to assign all but the simplest spectra.
In principle you can do better if you are able to measure the CA, CB and CO chemical shifts, as they can be predicted more accurately. I am currently developing a method to use this information for spectral assignment, so contact me off list if you are interested. However, you still need 13C labelled sample and triple-resonance experiments, so not sure how useful that would be to you. You can get some information from your spectrum based on chemical shift alone. For example, tryptophan and arginine side chain amines have distinctive chemical shifts, and can often be distinguished from the backbone. Similar considerations apply to the 13C HSQC, especially if you record the constant time version. Depending on sample concentration and your spectrometer sensitivity, you might be able to record this on a natural abundance sample. These approaches are likely to be less useful for larger proteins though. Best wishes, Alex ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/webadmin?SUBED1=CCP4BB&A=1
