Spectral evidence for structural difference between α-lactalbumin in powder and in solution

AbstractThe Raman spectrum of a protein consists of contributions from various amino-acids side chain modes together with modes originating from the peptide backbone. Among the latter, the amide I[1645-1680 cm-1] and the amide III [1230-1285 cm-1] are widely used to characterize the secondary structure of the peptide backbone. Among the former, mainly the disulfide linkage and the aromatic side chains are studied to get details about the tertiary structure and about the microenvironment of the side chains. Most of these lines are relatively strong and are well separated from the backbone modes.