[Vivekanandan Subramanian]

Hi Bimo,

You can run 1D 1H-NMR spectra at 5 different temperatures starting from 288 K until 308 K (if your peptide is stable) and see at what temperature you see good dispersion in the amide proton region (~ between 6.8 to 12 ppm). Select the optimal temperature/pH to see good dispersion in the amide proton region. Do TOCSY and NOESY at two different temperatures (say, 300 K and 303 K). This will help you during your peak assignment in NOESY when there is any overlapping residues present in the spectrum. I have done assignment and structure for 42 amino acid peptide and 65 amino acid protein structure (unlabelled) using 500 MHz Bruker spectrometer. If your peptide has beta-sheet conformation your job becomes relatively easy as you will have good dispersion in the amide region of the spectrum. Alpha helical peptide comes in a very narrow region and you will see lot of overlapping residues. But performing NOESY and TOCSY and two to three different temperatures can alleviate this problem to certain extent.

- Vivekanandan Subramanian