Raman spectroscopy of poly‐ L ‐proline in aqueous solution

The laser‐excited Raman spectra have been obtained of poly‐L‐proline in the solid and aqueous solution. In the solid state, the Raman spectra are of the form II which is the left‐handed helical form with the peptide bonds in the trans configuration. Dissolution of this form in water produced only minor changes in the Raman spectra. The differences in frequencies produced by dissolving the polymer are associated with vibrational modes of the pyrrolidine ring as indicated by comparison with the Raman spectrum of L‐proline. The similarity of the Raman spectra dictates that, the conformations of poly‐L‐proline chain are similar in the solid and aqueous solution.