Raman spectroscopy is a major analytical technique used for studying proteins. Its efficiency is strictly dependent on the correct attribution of the protein Raman bands. The Raman spectrum of a protein is complex due to their large number of bands. Among these bands, those bands belonging to the side chains of the amino acid residues are particularly important in monitoring chemical reactions involving proteins. The assignment of these bands is often difficult because their exact positions and intensities are dependent on the molecular environment. In the present work we have detected, attributed and compared the side chain Raman bands of three model proteins: Bovine Serum Albumin, β-lactoglobulin and Lysozyme. The attribution of the bands was based on the measurement and ab initio calculation of Raman spectra of several tripeptides of the form: Gly-AA-Gly, where the central amino acid AA was tryptophan, tyrosine, phenylalanine, methionine, histidine, lysine and leucine. The central amino acids were chosen as a reason of their significant reactivity.
Following on from the attribution of the bands a more detailed study of the oxidation of β-lactoglobulin by hydrogen peroxide will be presented making use of the changes in certain specific Raman bands. Finally, the use of Raman spectroscopy as a qualitative tool will be shown whereby Raman spectroscopy is used to confirm theoretical calculations.