Protein secondary structure from deep-UV resonance Raman spectroscopy

Raman spectra of proteins that are obtained with deep ultraviolet excitation contain resonance-enhanced amide bands of the polypeptide backbone, as well as aromatic side chain bands. The amide bands are sensitive to conformation, and can be used to estimate the backbone secondary structure. UV Raman spectra are reported at 206.5 and 197 nmi for a set of 12 proteins with varied secondary structure content, and are used to establish quantitative signatures of secondary structure via least-squares fitting. Amide band enhancement is greater at 197 nm, where basis spectra are established for beta-turn, as well as alpha-helix, beta-sheet and unordered structures; the lower signal strength at 206.5 nm does not provide a reliable spectrum for the first of these. Application of these basis spectra is illustrated for the melting of apo-myoglobin. The amide band positions and cross sections are discussed. Copyright (C) 2006 John Wiley & Sons, Ltd.