Typical 1D-1H-NMR spectra
Notes:
B) Resonance overlap: plenty of protons in the peptide /or protein, limited spectral dispersion, plenty of resonance overlap.
In the peptide less lines, but still overlap, in the protein: significantly more lines, but also better dispersed i.e. greater variety of observed frequencies.
As the peptide/protein are made of building blocks: natively they all have same “NMR” response = “native NMR-chemical shifts (random coil chemical shifts) =
Structure (tertiary, or just secondary) leads to resonance separation= different structural environments cause chemical shifts changes= better dispersion, amino acids become inequivalent. This facilitates the distinction of identical amino acid types at different positions in the sequence =>secondary structure assignment
and the delineation of the steric effect which cause the chemical shift dispersion => structure determination