Infrared Hole Burning of the Amino Group in Amino Acid and Peptide Salts

Monodeuterated derivatives of the salts of tyrosine, valine, glycylglycine, and glycylglycylglycine are investigated by infrared spectroscopy. Irradiation in the spectral region of the N -D stretch bands produces spectral holes and antiholes. These result from rotation of N-D-containing moieties. The holes and antiholes identify the vibrations of the amino group and provide information on the hydrogen-bonding environment. Both the various amino acid salts and the two peptide salts hole burn, suggesting that infrared hole burning will provide a useful tool for investigating a range of biologically interesting materials.