The (17)O-NMR shielding range and shielding time scale and detection of discrete hydrogen-bonded conformational states in peptides.
The (17)O-NMR shielding range and shielding time scale due to hydrogen-bonding interactions in peptides are critically evaluated relative to those of (1)H-NMR. Furthermore, the assumptions and conclusions in previous (17)O-NMR studies on the detection of discrete conformational states in peptides (V. Tsikaris et al., Biopolymers, 2000, Vol. 53, pp. 135-139) are reconsidered. Consistent examination of the method demonstrates that although (17)O shieldings of peptide oxygens are very sensitive to hydrogen bonding interactions, the (17)O-NMR shielding time scale is not advantageous compared to that of (1)H-NMR, and thus it is not suitable for the detection of discrete hydrogen-bonded conformational states in peptides. (17)O-NMR spectroscopy is prone to interpretation errors due to the formation of (17)O-labeled impurities during the synthetic procedures (A. Steinschneider et al., International Journal of Peptide and Protein Research, 1981, Vol. 18, pp. 324-333).
Gerothanassis
I P
IP
Section of Organic Chemistry and Biochemistry, Department of Chemistry, University of Ioannina, Ioannina GR-45110 Greece. igeroth@cc.uoi.gr
D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D010103:Oxygen Isotopes; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
D010103:Oxygen Isotopes; D010455:Peptides; D011506:Proteins