Raman spectroscopy of L‐tryptophan‐containing peptides adsorbed on a silver surface

Surfac‐enhanced Raman spectra of L ‐tryptophanylglycine ( L ‐Trp‐Gly) and L ‐tryptophanylglycylglycine ( L ‐Trp‐Gly‐Gly) adsorbed on a silver surface were obtained. More detailed investigations than in a previous study on the surface‐enhanced Raman scattering from L ‐tryptophan ( L ‐ Trp) and glycyl‐ L ‐tryptophan (Gly‐ L ‐Trp) were also made. It was found that L ‐Trp and the above peptides adsorb on the silver surface via both the carboxylate (COO − ) and the amino (NH 2 ) groups. Interestingly, the nitrogen atom of the indole ring of L ‐Trp was found to bind to the surface only when L ‐Trp is the C‐terminal residue.