Solvent suppression in NMR-spectra

 

Molarity of protons in H₂O = 110 M

c[protein] about 1-5 mM

 

Thus :

1.     Continuous irradiation with low-energetic RF or

2.     pulse – irradiation at water resonance

 

        e.g. (p/2)_y - t - (p/2)_-y      Gueron – pulse sequence

 

Problems:

 

ad 1.

*           Homogeneity of field

*           Bloch-Siegert effect = change of shift near resonance line

*           Suppression of resonance lines at water resonance

 

ad 2.

*           Large transfer peaks of energy-transferring protons within the biomolecule

*           Loss of all cross-peaks