Abstract

Resonance Raman spectroscopy of heme proteins and the visual pigments has provided valuable insights into the mechanism of action of these proteins. The performance of Raman experiments with ultraviolet radiation permits resonance with nonchromophoric components of proteins including the peptide bond itself.^1,2 Fluorescence from the aromatic residues of proteins does not obscure the Raman signal because the fluorescence occurs at longer wavelengths. The peptide bond gives rise to new Raman active bands with ultraviolet excitation.² The imino linkage of X-proline sequences results in absorption in the 220–240-nm range where normal amino linkages are transparent. This permits the selective excitation of this group relative to the predominant amino peptide bonds. This is of particular interest with respect to the involvement of isomerization of the X-proline linkage in protein folding. Recent results using radiation in the 150–200-nm region are presented.

© 1986 Optical Society of America